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  • Sqlite insertion problem

    - by Devi
    Hi, I had sqlite database for my application I am able to retrieve values from my sqlite table and inserting values with no sql error but unable to find in sqlite table....please do needful help for this problem. I just stucked up at this point plz help me here is my code NSMutableString *registrationquery=[NSMutableString stringWithFormat:@"insert into tbl_kicks values ('%@','%@','%@')",[totalkicks text],[sessionstart text],[sessionstart text],@"0"]; //NSString *sqlNSString = [NSString stringWithFormat:@"INSERT INTO 'tbl_kicks' VALUES('%d','%@','%@');", // 4,sessionstart.text, appDelegate.note]; const char *sqlString = [registrationquery UTF8String]; char *sqlError; sqlite3_exec( appDelegate.database, sqlString, NULL, NULL, &sqlError );

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  • C++ how to store integer into a binary file??

    - by blaxc
    i gt a struct with 2 integer, i want to store them in a binary file and read it again... here is my code... struct pw { int a; int b; }; void main(){ pw* p = new pw(); pw* q = new pw(); std::ofstream fout(ADMIN_FILE, ios_base::out | ios_base::binary | ios_base::trunc); std::ifstream fin(ADMIN_FILE, ios_base::in | ios_base::binary); p->a=123; p->b=321; fout.write((const char*)p, sizeof(pw)); fin.write((char*)q, sizeof(pw)); fin.close(); cout<< q->a << endl;} my output is 0. anyone can tell me what is the problem?

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  • Using popen() to invoke a shell command?

    - by Anvar
    When running the following code through xcode I get inconsistent behavior. Sometimes it prints the git version correctly, other times it doesn't print anything. The return code from the shell command is always 0 though. Any ideas on why this might be? What am I doing wrong? #define BUFFER_SIZE 256 int main (int argc, const char * argv[]) { FILE *fpipe; char *command="/opt/local/bin/git --version"; char line[BUFFER_SIZE]; if ( !(fpipe = (FILE*)popen(command, "r")) ) { // If fpipe is NULL perror("Problems with pipe"); exit(1); } while ( fgets( line, sizeof(char) * BUFFER_SIZE, fpipe)) { // Inconsistent (happens sometimes) printf("READING LINE"); printf("%s", line); } int status = pclose(fpipe); if (status != 0) { // Never happens printf("Strange error code: %d", status); } return 0; }

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  • In a C++ template, is it allowed to return an object with specific type parameters?

    - by nieldw
    When I've got a template with certain type parameters, is it allowed for a function to return an object of this same template, but with different types? In other words, is the following allowed? template<class edgeDecor, class vertexDecor, bool dir> Graph<edgeDecor,int,dir> Graph<edgeDecor,vertexDecor,dir>::Dijkstra(vertex s, bool print = false) const { /* Construct new Graph with apropriate decorators */ Graph<edgeDecor,int,dir> span = new Graph<edgeDecor,int,dir>(); /* ... */ return span; }; If this is not allowed, how can I accomplish the same kind of thing?

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  • Sending some byte at time

    - by user1417815
    I'm trying to figure out way to send some amount of text from the string ech time until it reach the end of the string, example: const char* the_string = "hello world, i'm happy to meet you all. Let be friends or maybe more, but nothing less" Output: hello world Output: , i'm happy to meet you all. Output: Let be friends or maybe more Output: , but nothing less stop: no more bytes to send. the problem i have searched google, but didn't understand the examples, i spent 4 days trying find a good way, also that sendt 5 bytes at time, but in case there is less, then send them until you are at the end of the string. please help me out guys, i will accept a C or C++ way, as long it works and well explained.

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  • question regarding "this" pointer in c++

    - by sil3nt
    hello there, i have been given class with int variables x and y in private, and an operator overload function, class Bag{ private: int x; int y; public: Bag(); ~Bag(); //....... //.....etc }; Bag operator+ (Bag new) const{ Bag result(*this); //what does this mean? result.x += new.x; result.y += new.y; } What is the effect of having "Bag result(*this);" there?.

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  • How to define an array inside a function in C?

    - by Arunav Dev
    So in my source file I have the folowin function: void update(state* old_state, state* measurement, uint32_t size) { state new_state[size]; //some function using measurement and old_state and returning the result in newstate arm_fadd_32(measurement,old_state,newstate,size); // rest of the code } Now the compiler throws an error saying that error#28:expression must have a constant value. I think it's due to the fact that even though inside the method the size local variable is not changing the compiler is expecting a constant while defining the size. I have tried the following: int const a = size; and then tried to reinitialize it says constant value is not known. I did some research in internet and it appears that there is no easier way without using malloc, which I don't want to since I am using the code for some embedded application. Is there a way to avoid this problem without really using malloc? Thanks in advance guys!

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  • xcode 4 creating a 2d grid (range and domain)

    - by user1706978
    I'm learning how to program c and i'm trying to make a program the finds the range (using an equation with x as the domain) of a 2d grid...ive already attempted it, but it's giving me all these errors on Xcode, any help?(As you can see, I'm quite stuck!) #include <stdio.h> #include <stdlib.h> float domain; float domain = 2.0; float domainsol(float x ) { domain = x; float func = 1.25 * x + 5.0; return func; } int main(int argc, const char * argv[]) { }

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  • I was making this program and the server wont send to the client

    - by crstin
    void CApplication::SendData( const char pBuffer[] ) { if( pBuffer == NULL ) { Log()->Write( ELogMessageType_ERROR, "Cannot send NULL message."); return; } // calculate the size of that data unsigned long messageSize = strlen( pBuffer ); // fix our byte ordering messageSize = htonl( messageSize ); if( isServer == true ) { for( unsigned int i = ESocket_CLIENT0; i < ESocket_MAX; ++i ) { // send the message size if( m_Socket[ i ] > 0 ) { if( send( m_Socket[ i ], (char*)&messageSize, sizeof( messageSize ), 0 ) == SOCKET_ERROR ) { Log()->Write( ELogMessageType_ERROR, "[Application] Send error: %i to socket %i", WSAGetLastError(), m_Socket[ i ] ); continue; } // fix our message size back to host ordering messageSize = ntohl(messageSize); // send the actual message if( send( m_Socket[ i ], pBuffer, messageSize, 0 ) == SOCKET_ERROR ) { Log()->Write( ELogMessageType_ERROR, "[Application] Send error: %i to socket %i", WSAGetLastError(), m_Socket[ i ] ); continue; } Log()->Write( ELogMessageType_MESSAGE, "[Application] SEND: %s", pBuffer ); } } }

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  • including .h files.

    - by Max
    Suppose I have two .h files: A.h and B.h. Moreover, A.h includes B.h itself: B.h - declares class B. class B { ... }; A.h - declares class A, which uses class B. #include B.h class A { void SomeFunction(const B& b); }; Now, I have some .cpp file, that uses both A and B classes (B class maybe used not only in A::SomeFunction(B)) What are the pluses to include both A.h and B.h (instead of only A.h) from the perspective of design-patterns and coding style.

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  • Do I really need to return Type::size_type?

    - by dehmann
    I often have classes that are mostly just wrappers around some STL container, like this: class Foo { public: typedef std::vector<whatever> Vec; typedef Vec::size_type; const Vec& GetVec() { return vec_; } size_type size() { return vec_.size() } private: Vec vec_; }; I am not so sure about returning size_type. Often, some function will call size() and pass that value on to another function and that one will use it and maybe pass it on. Now everyone has to include that Foo header, although I'm really just passing some size value around, which should just be unsigned int anyway ...? What is the right thing to do here? Is it best practice to really use size_type everywhere?

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  • C++ putting a 2d array of floats into a char*

    - by sam
    Hello, I'm trying to take a 2d vector of floats (input) and put them into a char* (output) in c++. void foo(const std::vector<std::vector<float> > &input, char* &output ) { char charBuf[sizeof(output)]; int counter = 0; for(unsigned int i=0; i<input.size(); i++) { for(unsigned int p=0; p<input.at(i).size(); p++) { //what the heck goes here } }

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  • C++ array of classes

    - by nickik
    I working on a game but I have a problem with the initialization of the level. (feld is just field in german) class level{ private: feld spielfeld[10][10]; public: /* other staff */ void init_feld(); }; void level::init_feld() { for(int i=0;i!=10;i++){ for(int n=0;n!=10;n++){ spielfeld[i][n] = new feld(land, i, n); } } } The Error: Error: no match for »operator=« in »((level*)this)-level::spielfeld[i][n] = (operator new(24u), (, ((feld*))))« /home/nick/stratego/feld.h:18:11: Remark: candidate is: feld& feld::operator=(const feld&) Process terminated with status 1 (0 minutes, 0 seconds) 2 errors, 0 warnings

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  • Subtle C++ mistake, can you spot it?

    - by aaa
    I ran into a subtle C++ gotcha, took me while to resolve it. Can you spot it? class synchronized_container { boost::mutex mutex_; std::vector <T> container_; void push_back(const T &value) { boost::scoped_lock(mutex_); // raii mutex lock container_.push_back(value); } ... }; scoped lock is a raii mutex lock, obtains lock on constructor, release lock in destructor. The program will work as expected in serial, but will may occasionally produce weird stuff with more than one thread.

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  • Checking variable from a different class in C#

    - by Josh
    Greetings- I have 2 classes. One is called "Programs" and the other is called "Logs". The class called Programs has public const string m_sEnviron = ""; near the top and I need to check what the m_sEnviron variable is set to through my class called Logs. The variable m_sEnviron will get set from a scheduler called Tidal so how can I check its value from a different class. If this is not the best to do this then please let me know what the better ways are. Thanks in advance. Regards,

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  • strcat implementation

    - by skydoor
    I tried to implement the strcat by myself, and I found the strcat implementation from Wiki like this......but when I use it, there is segmentation fault. What's from with the code below? char * strcat(char *dest, const char *src) { size_t i,j; for (i = 0; dest[i] != '\0'; i++) ; for (j = 0; src[j] != '\0'; j++) dest[i+j] = src[j]; dest[i+j] = '\0'; return dest; }

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  • Pointer aliasing- in C++0x

    - by DeadMG
    I'm thinking about (just as an idea) disjointed pointer aliasing in C++0x. I was thinking about seeing if it could be implemented similarly to const correctness- that is, enforced by the compiler. What would be the requirements for such a thing? As this is more of a thought experiment, I'm perfectly happy to look at solutions that destroy legacy code or redefine half the language and that kind of thing. What I'd really rather not do is have, say, restrict from C99 where the programmer just promises it. It should be enforced.

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  • Compare to a defined constants in C?

    - by J.W.
    I am trying to compare to a defined constants in C, and I have simplified my program to the following.. #include "stdio.h" #include "stdlib.h" #define INVALID_VALUE -999; int main(int argc, const char* argv[]) { int test=0; if(test==INVALID_VALUE) //The error line.. return INVALID_VALUE; return 0; }; And when I use gcc to compile. it gives out error "error: expected ‘)’ before ‘;’ token" Any reason that this cannot be done.

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  • weird index behavior

    - by TasostheGreat
    I have set up my table with an index only on done_status(done_status =INT), when I use EXPLAIN SELECT * FROM reminder WHERE done_status=2 i get this back id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE reminder ALL done_status NULL NULL NULL 5 Using where but when I give this command EXPLAIN SELECT * FROM reminder WHERE done_status=1 that's what I get back: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE reminder ref done_status done_status 4 const 2 first time it shows me it uses 5 rows second time 2 rows I don't think the index works, if I understood it right first time it should give me 3 rows. What do I do wrong? SHOW INDEX FROM reminder: Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment reminder 1 done_status 1 done_status A 5 NULL NULL BTREE

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  • Returning a struct from a class method

    - by tree
    I have a header file that looks something like the following: class Model { private: struct coord { int x; int y; } xy; public: .... coord get() const { return xy; } }; And in yet another file (assume ModelObject exists): struct c { int x; int y; void operator = (c &rhs) { x = rhs.x; y = rhs.y; }; } xy; xy = ModelObject->get(); The compiler throws an error that says there is no known covnersion from coord to c. I believe it is because it doesn't know about coord type because it is declared inside of a class header. I can get around that by declaring the struct outside of the class, but I was wondering if it is possible to do the way I am, or is this generally considered bad practice

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  • New features of C# 4.0

    This article covers New features of C# 4.0. Article has been divided into below sections. Introduction. Dynamic Lookup. Named and Optional Arguments. Features for COM interop. Variance. Relationship with Visual Basic. Resources. Other interested readings… 22 New Features of Visual Studio 2008 for .NET Professionals 50 New Features of SQL Server 2008 IIS 7.0 New features Introduction It is now close to a year since Microsoft Visual C# 3.0 shipped as part of Visual Studio 2008. In the VS Managed Languages team we are hard at work on creating the next version of the language (with the unsurprising working title of C# 4.0), and this document is a first public description of the planned language features as we currently see them. Please be advised that all this is in early stages of production and is subject to change. Part of the reason for sharing our plans in public so early is precisely to get the kind of feedback that will cause us to improve the final product before it rolls out. Simultaneously with the publication of this whitepaper, a first public CTP (community technology preview) of Visual Studio 2010 is going out as a Virtual PC image for everyone to try. Please use it to play and experiment with the features, and let us know of any thoughts you have. We ask for your understanding and patience working with very early bits, where especially new or newly implemented features do not have the quality or stability of a final product. The aim of the CTP is not to give you a productive work environment but to give you the best possible impression of what we are working on for the next release. The CTP contains a number of walkthroughs, some of which highlight the new language features of C# 4.0. Those are excellent for getting a hands-on guided tour through the details of some common scenarios for the features. You may consider this whitepaper a companion document to these walkthroughs, complementing them with a focus on the overall language features and how they work, as opposed to the specifics of the concrete scenarios. C# 4.0 The major theme for C# 4.0 is dynamic programming. Increasingly, objects are “dynamic” in the sense that their structure and behavior is not captured by a static type, or at least not one that the compiler knows about when compiling your program. Some examples include a. objects from dynamic programming languages, such as Python or Ruby b. COM objects accessed through IDispatch c. ordinary .NET types accessed through reflection d. objects with changing structure, such as HTML DOM objects While C# remains a statically typed language, we aim to vastly improve the interaction with such objects. A secondary theme is co-evolution with Visual Basic. Going forward we will aim to maintain the individual character of each language, but at the same time important new features should be introduced in both languages at the same time. They should be differentiated more by style and feel than by feature set. The new features in C# 4.0 fall into four groups: Dynamic lookup Dynamic lookup allows you to write method, operator and indexer calls, property and field accesses, and even object invocations which bypass the C# static type checking and instead gets resolved at runtime. Named and optional parameters Parameters in C# can now be specified as optional by providing a default value for them in a member declaration. When the member is invoked, optional arguments can be omitted. Furthermore, any argument can be passed by parameter name instead of position. COM specific interop features Dynamic lookup as well as named and optional parameters both help making programming against COM less painful than today. On top of that, however, we are adding a number of other small features that further improve the interop experience. Variance It used to be that an IEnumerable<string> wasn’t an IEnumerable<object>. Now it is – C# embraces type safe “co-and contravariance” and common BCL types are updated to take advantage of that. Dynamic Lookup Dynamic lookup allows you a unified approach to invoking things dynamically. With dynamic lookup, when you have an object in your hand you do not need to worry about whether it comes from COM, IronPython, the HTML DOM or reflection; you just apply operations to it and leave it to the runtime to figure out what exactly those operations mean for that particular object. This affords you enormous flexibility, and can greatly simplify your code, but it does come with a significant drawback: Static typing is not maintained for these operations. A dynamic object is assumed at compile time to support any operation, and only at runtime will you get an error if it wasn’t so. Oftentimes this will be no loss, because the object wouldn’t have a static type anyway, in other cases it is a tradeoff between brevity and safety. In order to facilitate this tradeoff, it is a design goal of C# to allow you to opt in or opt out of dynamic behavior on every single call. The dynamic type C# 4.0 introduces a new static type called dynamic. When you have an object of type dynamic you can “do things to it” that are resolved only at runtime: dynamic d = GetDynamicObject(…); d.M(7); The C# compiler allows you to call a method with any name and any arguments on d because it is of type dynamic. At runtime the actual object that d refers to will be examined to determine what it means to “call M with an int” on it. The type dynamic can be thought of as a special version of the type object, which signals that the object can be used dynamically. It is easy to opt in or out of dynamic behavior: any object can be implicitly converted to dynamic, “suspending belief” until runtime. Conversely, there is an “assignment conversion” from dynamic to any other type, which allows implicit conversion in assignment-like constructs: dynamic d = 7; // implicit conversion int i = d; // assignment conversion Dynamic operations Not only method calls, but also field and property accesses, indexer and operator calls and even delegate invocations can be dispatched dynamically: dynamic d = GetDynamicObject(…); d.M(7); // calling methods d.f = d.P; // getting and settings fields and properties d[“one”] = d[“two”]; // getting and setting thorugh indexers int i = d + 3; // calling operators string s = d(5,7); // invoking as a delegate The role of the C# compiler here is simply to package up the necessary information about “what is being done to d”, so that the runtime can pick it up and determine what the exact meaning of it is given an actual object d. Think of it as deferring part of the compiler’s job to runtime. The result of any dynamic operation is itself of type dynamic. Runtime lookup At runtime a dynamic operation is dispatched according to the nature of its target object d: COM objects If d is a COM object, the operation is dispatched dynamically through COM IDispatch. This allows calling to COM types that don’t have a Primary Interop Assembly (PIA), and relying on COM features that don’t have a counterpart in C#, such as indexed properties and default properties. Dynamic objects If d implements the interface IDynamicObject d itself is asked to perform the operation. Thus by implementing IDynamicObject a type can completely redefine the meaning of dynamic operations. This is used intensively by dynamic languages such as IronPython and IronRuby to implement their own dynamic object models. It will also be used by APIs, e.g. by the HTML DOM to allow direct access to the object’s properties using property syntax. Plain objects Otherwise d is a standard .NET object, and the operation will be dispatched using reflection on its type and a C# “runtime binder” which implements C#’s lookup and overload resolution semantics at runtime. This is essentially a part of the C# compiler running as a runtime component to “finish the work” on dynamic operations that was deferred by the static compiler. Example Assume the following code: dynamic d1 = new Foo(); dynamic d2 = new Bar(); string s; d1.M(s, d2, 3, null); Because the receiver of the call to M is dynamic, the C# compiler does not try to resolve the meaning of the call. Instead it stashes away information for the runtime about the call. This information (often referred to as the “payload”) is essentially equivalent to: “Perform an instance method call of M with the following arguments: 1. a string 2. a dynamic 3. a literal int 3 4. a literal object null” At runtime, assume that the actual type Foo of d1 is not a COM type and does not implement IDynamicObject. In this case the C# runtime binder picks up to finish the overload resolution job based on runtime type information, proceeding as follows: 1. Reflection is used to obtain the actual runtime types of the two objects, d1 and d2, that did not have a static type (or rather had the static type dynamic). The result is Foo for d1 and Bar for d2. 2. Method lookup and overload resolution is performed on the type Foo with the call M(string,Bar,3,null) using ordinary C# semantics. 3. If the method is found it is invoked; otherwise a runtime exception is thrown. Overload resolution with dynamic arguments Even if the receiver of a method call is of a static type, overload resolution can still happen at runtime. This can happen if one or more of the arguments have the type dynamic: Foo foo = new Foo(); dynamic d = new Bar(); var result = foo.M(d); The C# runtime binder will choose between the statically known overloads of M on Foo, based on the runtime type of d, namely Bar. The result is again of type dynamic. The Dynamic Language Runtime An important component in the underlying implementation of dynamic lookup is the Dynamic Language Runtime (DLR), which is a new API in .NET 4.0. The DLR provides most of the infrastructure behind not only C# dynamic lookup but also the implementation of several dynamic programming languages on .NET, such as IronPython and IronRuby. Through this common infrastructure a high degree of interoperability is ensured, but just as importantly the DLR provides excellent caching mechanisms which serve to greatly enhance the efficiency of runtime dispatch. To the user of dynamic lookup in C#, the DLR is invisible except for the improved efficiency. However, if you want to implement your own dynamically dispatched objects, the IDynamicObject interface allows you to interoperate with the DLR and plug in your own behavior. This is a rather advanced task, which requires you to understand a good deal more about the inner workings of the DLR. For API writers, however, it can definitely be worth the trouble in order to vastly improve the usability of e.g. a library representing an inherently dynamic domain. Open issues There are a few limitations and things that might work differently than you would expect. · The DLR allows objects to be created from objects that represent classes. However, the current implementation of C# doesn’t have syntax to support this. · Dynamic lookup will not be able to find extension methods. Whether extension methods apply or not depends on the static context of the call (i.e. which using clauses occur), and this context information is not currently kept as part of the payload. · Anonymous functions (i.e. lambda expressions) cannot appear as arguments to a dynamic method call. The compiler cannot bind (i.e. “understand”) an anonymous function without knowing what type it is converted to. One consequence of these limitations is that you cannot easily use LINQ queries over dynamic objects: dynamic collection = …; var result = collection.Select(e => e + 5); If the Select method is an extension method, dynamic lookup will not find it. Even if it is an instance method, the above does not compile, because a lambda expression cannot be passed as an argument to a dynamic operation. There are no plans to address these limitations in C# 4.0. Named and Optional Arguments Named and optional parameters are really two distinct features, but are often useful together. Optional parameters allow you to omit arguments to member invocations, whereas named arguments is a way to provide an argument using the name of the corresponding parameter instead of relying on its position in the parameter list. Some APIs, most notably COM interfaces such as the Office automation APIs, are written specifically with named and optional parameters in mind. Up until now it has been very painful to call into these APIs from C#, with sometimes as many as thirty arguments having to be explicitly passed, most of which have reasonable default values and could be omitted. Even in APIs for .NET however you sometimes find yourself compelled to write many overloads of a method with different combinations of parameters, in order to provide maximum usability to the callers. Optional parameters are a useful alternative for these situations. Optional parameters A parameter is declared optional simply by providing a default value for it: public void M(int x, int y = 5, int z = 7); Here y and z are optional parameters and can be omitted in calls: M(1, 2, 3); // ordinary call of M M(1, 2); // omitting z – equivalent to M(1, 2, 7) M(1); // omitting both y and z – equivalent to M(1, 5, 7) Named and optional arguments C# 4.0 does not permit you to omit arguments between commas as in M(1,,3). This could lead to highly unreadable comma-counting code. Instead any argument can be passed by name. Thus if you want to omit only y from a call of M you can write: M(1, z: 3); // passing z by name or M(x: 1, z: 3); // passing both x and z by name or even M(z: 3, x: 1); // reversing the order of arguments All forms are equivalent, except that arguments are always evaluated in the order they appear, so in the last example the 3 is evaluated before the 1. Optional and named arguments can be used not only with methods but also with indexers and constructors. Overload resolution Named and optional arguments affect overload resolution, but the changes are relatively simple: A signature is applicable if all its parameters are either optional or have exactly one corresponding argument (by name or position) in the call which is convertible to the parameter type. Betterness rules on conversions are only applied for arguments that are explicitly given – omitted optional arguments are ignored for betterness purposes. If two signatures are equally good, one that does not omit optional parameters is preferred. M(string s, int i = 1); M(object o); M(int i, string s = “Hello”); M(int i); M(5); Given these overloads, we can see the working of the rules above. M(string,int) is not applicable because 5 doesn’t convert to string. M(int,string) is applicable because its second parameter is optional, and so, obviously are M(object) and M(int). M(int,string) and M(int) are both better than M(object) because the conversion from 5 to int is better than the conversion from 5 to object. Finally M(int) is better than M(int,string) because no optional arguments are omitted. Thus the method that gets called is M(int). Features for COM interop Dynamic lookup as well as named and optional parameters greatly improve the experience of interoperating with COM APIs such as the Office Automation APIs. In order to remove even more of the speed bumps, a couple of small COM-specific features are also added to C# 4.0. Dynamic import Many COM methods accept and return variant types, which are represented in the PIAs as object. In the vast majority of cases, a programmer calling these methods already knows the static type of a returned object from context, but explicitly has to perform a cast on the returned value to make use of that knowledge. These casts are so common that they constitute a major nuisance. In order to facilitate a smoother experience, you can now choose to import these COM APIs in such a way that variants are instead represented using the type dynamic. In other words, from your point of view, COM signatures now have occurrences of dynamic instead of object in them. This means that you can easily access members directly off a returned object, or you can assign it to a strongly typed local variable without having to cast. To illustrate, you can now say excel.Cells[1, 1].Value = "Hello"; instead of ((Excel.Range)excel.Cells[1, 1]).Value2 = "Hello"; and Excel.Range range = excel.Cells[1, 1]; instead of Excel.Range range = (Excel.Range)excel.Cells[1, 1]; Compiling without PIAs Primary Interop Assemblies are large .NET assemblies generated from COM interfaces to facilitate strongly typed interoperability. They provide great support at design time, where your experience of the interop is as good as if the types where really defined in .NET. However, at runtime these large assemblies can easily bloat your program, and also cause versioning issues because they are distributed independently of your application. The no-PIA feature allows you to continue to use PIAs at design time without having them around at runtime. Instead, the C# compiler will bake the small part of the PIA that a program actually uses directly into its assembly. At runtime the PIA does not have to be loaded. Omitting ref Because of a different programming model, many COM APIs contain a lot of reference parameters. Contrary to refs in C#, these are typically not meant to mutate a passed-in argument for the subsequent benefit of the caller, but are simply another way of passing value parameters. It therefore seems unreasonable that a C# programmer should have to create temporary variables for all such ref parameters and pass these by reference. Instead, specifically for COM methods, the C# compiler will allow you to pass arguments by value to such a method, and will automatically generate temporary variables to hold the passed-in values, subsequently discarding these when the call returns. In this way the caller sees value semantics, and will not experience any side effects, but the called method still gets a reference. Open issues A few COM interface features still are not surfaced in C#. Most notably these include indexed properties and default properties. As mentioned above these will be respected if you access COM dynamically, but statically typed C# code will still not recognize them. There are currently no plans to address these remaining speed bumps in C# 4.0. Variance An aspect of generics that often comes across as surprising is that the following is illegal: IList<string> strings = new List<string>(); IList<object> objects = strings; The second assignment is disallowed because strings does not have the same element type as objects. There is a perfectly good reason for this. If it were allowed you could write: objects[0] = 5; string s = strings[0]; Allowing an int to be inserted into a list of strings and subsequently extracted as a string. This would be a breach of type safety. However, there are certain interfaces where the above cannot occur, notably where there is no way to insert an object into the collection. Such an interface is IEnumerable<T>. If instead you say: IEnumerable<object> objects = strings; There is no way we can put the wrong kind of thing into strings through objects, because objects doesn’t have a method that takes an element in. Variance is about allowing assignments such as this in cases where it is safe. The result is that a lot of situations that were previously surprising now just work. Covariance In .NET 4.0 the IEnumerable<T> interface will be declared in the following way: public interface IEnumerable<out T> : IEnumerable { IEnumerator<T> GetEnumerator(); } public interface IEnumerator<out T> : IEnumerator { bool MoveNext(); T Current { get; } } The “out” in these declarations signifies that the T can only occur in output position in the interface – the compiler will complain otherwise. In return for this restriction, the interface becomes “covariant” in T, which means that an IEnumerable<A> is considered an IEnumerable<B> if A has a reference conversion to B. As a result, any sequence of strings is also e.g. a sequence of objects. This is useful e.g. in many LINQ methods. Using the declarations above: var result = strings.Union(objects); // succeeds with an IEnumerable<object> This would previously have been disallowed, and you would have had to to some cumbersome wrapping to get the two sequences to have the same element type. Contravariance Type parameters can also have an “in” modifier, restricting them to occur only in input positions. An example is IComparer<T>: public interface IComparer<in T> { public int Compare(T left, T right); } The somewhat baffling result is that an IComparer<object> can in fact be considered an IComparer<string>! It makes sense when you think about it: If a comparer can compare any two objects, it can certainly also compare two strings. This property is referred to as contravariance. A generic type can have both in and out modifiers on its type parameters, as is the case with the Func<…> delegate types: public delegate TResult Func<in TArg, out TResult>(TArg arg); Obviously the argument only ever comes in, and the result only ever comes out. Therefore a Func<object,string> can in fact be used as a Func<string,object>. Limitations Variant type parameters can only be declared on interfaces and delegate types, due to a restriction in the CLR. Variance only applies when there is a reference conversion between the type arguments. For instance, an IEnumerable<int> is not an IEnumerable<object> because the conversion from int to object is a boxing conversion, not a reference conversion. Also please note that the CTP does not contain the new versions of the .NET types mentioned above. In order to experiment with variance you have to declare your own variant interfaces and delegate types. COM Example Here is a larger Office automation example that shows many of the new C# features in action. using System; using System.Diagnostics; using System.Linq; using Excel = Microsoft.Office.Interop.Excel; using Word = Microsoft.Office.Interop.Word; class Program { static void Main(string[] args) { var excel = new Excel.Application(); excel.Visible = true; excel.Workbooks.Add(); // optional arguments omitted excel.Cells[1, 1].Value = "Process Name"; // no casts; Value dynamically excel.Cells[1, 2].Value = "Memory Usage"; // accessed var processes = Process.GetProcesses() .OrderByDescending(p =&gt; p.WorkingSet) .Take(10); int i = 2; foreach (var p in processes) { excel.Cells[i, 1].Value = p.ProcessName; // no casts excel.Cells[i, 2].Value = p.WorkingSet; // no casts i++; } Excel.Range range = excel.Cells[1, 1]; // no casts Excel.Chart chart = excel.ActiveWorkbook.Charts. Add(After: excel.ActiveSheet); // named and optional arguments chart.ChartWizard( Source: range.CurrentRegion, Title: "Memory Usage in " + Environment.MachineName); //named+optional chart.ChartStyle = 45; chart.CopyPicture(Excel.XlPictureAppearance.xlScreen, Excel.XlCopyPictureFormat.xlBitmap, Excel.XlPictureAppearance.xlScreen); var word = new Word.Application(); word.Visible = true; word.Documents.Add(); // optional arguments word.Selection.Paste(); } } The code is much more terse and readable than the C# 3.0 counterpart. Note especially how the Value property is accessed dynamically. This is actually an indexed property, i.e. a property that takes an argument; something which C# does not understand. However the argument is optional. Since the access is dynamic, it goes through the runtime COM binder which knows to substitute the default value and call the indexed property. Thus, dynamic COM allows you to avoid accesses to the puzzling Value2 property of Excel ranges. Relationship with Visual Basic A number of the features introduced to C# 4.0 already exist or will be introduced in some form or other in Visual Basic: · Late binding in VB is similar in many ways to dynamic lookup in C#, and can be expected to make more use of the DLR in the future, leading to further parity with C#. · Named and optional arguments have been part of Visual Basic for a long time, and the C# version of the feature is explicitly engineered with maximal VB interoperability in mind. · NoPIA and variance are both being introduced to VB and C# at the same time. VB in turn is adding a number of features that have hitherto been a mainstay of C#. As a result future versions of C# and VB will have much better feature parity, for the benefit of everyone. Resources All available resources concerning C# 4.0 can be accessed through the C# Dev Center. Specifically, this white paper and other resources can be found at the Code Gallery site. Enjoy! span.fullpost {display:none;}

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  • Introducing the Earthquake Locator – A Bing Maps Silverlight Application, part 1

    - by Bobby Diaz
    Update: Live demo and source code now available!  The recent wave of earthquakes (no pun intended) being reported in the news got me wondering about the frequency and severity of earthquakes around the world. Since I’ve been doing a lot of Silverlight development lately, I decided to scratch my curiosity with a nice little Bing Maps application that will show the location and relative strength of recent seismic activity. Here is a list of technologies this application will utilize, so be sure to have everything downloaded and installed if you plan on following along. Silverlight 3 WCF RIA Services Bing Maps Silverlight Control * Managed Extensibility Framework (optional) MVVM Light Toolkit (optional) log4net (optional) * If you are new to Bing Maps or have not signed up for a Developer Account, you will need to visit www.bingmapsportal.com to request a Bing Maps key for your application. Getting Started We start out by creating a new Silverlight Application called EarthquakeLocator and specify that we want to automatically create the Web Application Project with RIA Services enabled. I cleaned up the web app by removing the Default.aspx and EarthquakeLocatorTestPage.html. Then I renamed the EarthquakeLocatorTestPage.aspx to Default.aspx and set it as my start page. I also set the development server to use a specific port, as shown below. RIA Services Next, I created a Services folder in the EarthquakeLocator.Web project and added a new Domain Service Class called EarthquakeService.cs. This is the RIA Services Domain Service that will provide earthquake data for our client application. I am not using LINQ to SQL or Entity Framework, so I will use the <empty domain service class> option. We will be pulling data from an external Atom feed, but this example could just as easily pull data from a database or another web service. This is an important distinction to point out because each scenario I just mentioned could potentially use a different Domain Service base class (i.e. LinqToSqlDomainService<TDataContext>). Now we can start adding Query methods to our EarthquakeService that pull data from the USGS web site. Here is the complete code for our service class: using System; using System.Collections.Generic; using System.IO; using System.Linq; using System.ServiceModel.Syndication; using System.Web.DomainServices; using System.Web.Ria; using System.Xml; using log4net; using EarthquakeLocator.Web.Model;   namespace EarthquakeLocator.Web.Services {     /// <summary>     /// Provides earthquake data to client applications.     /// </summary>     [EnableClientAccess()]     public class EarthquakeService : DomainService     {         private static readonly ILog log = LogManager.GetLogger(typeof(EarthquakeService));           // USGS Data Feeds: http://earthquake.usgs.gov/earthquakes/catalogs/         private const string FeedForPreviousDay =             "http://earthquake.usgs.gov/earthquakes/catalogs/1day-M2.5.xml";         private const string FeedForPreviousWeek =             "http://earthquake.usgs.gov/earthquakes/catalogs/7day-M2.5.xml";           /// <summary>         /// Gets the earthquake data for the previous week.         /// </summary>         /// <returns>A queryable collection of <see cref="Earthquake"/> objects.</returns>         public IQueryable<Earthquake> GetEarthquakes()         {             var feed = GetFeed(FeedForPreviousWeek);             var list = new List<Earthquake>();               if ( feed != null )             {                 foreach ( var entry in feed.Items )                 {                     var quake = CreateEarthquake(entry);                     if ( quake != null )                     {                         list.Add(quake);                     }                 }             }               return list.AsQueryable();         }           /// <summary>         /// Creates an <see cref="Earthquake"/> object for each entry in the Atom feed.         /// </summary>         /// <param name="entry">The Atom entry.</param>         /// <returns></returns>         private Earthquake CreateEarthquake(SyndicationItem entry)         {             Earthquake quake = null;             string title = entry.Title.Text;             string summary = entry.Summary.Text;             string point = GetElementValue<String>(entry, "point");             string depth = GetElementValue<String>(entry, "elev");             string utcTime = null;             string localTime = null;             string depthDesc = null;             double? magnitude = null;             double? latitude = null;             double? longitude = null;             double? depthKm = null;               if ( !String.IsNullOrEmpty(title) && title.StartsWith("M") )             {                 title = title.Substring(2, title.IndexOf(',')-3).Trim();                 magnitude = TryParse(title);             }             if ( !String.IsNullOrEmpty(point) )             {                 var values = point.Split(' ');                 if ( values.Length == 2 )                 {                     latitude = TryParse(values[0]);                     longitude = TryParse(values[1]);                 }             }             if ( !String.IsNullOrEmpty(depth) )             {                 depthKm = TryParse(depth);                 if ( depthKm != null )                 {                     depthKm = Math.Round((-1 * depthKm.Value) / 100, 2);                 }             }             if ( !String.IsNullOrEmpty(summary) )             {                 summary = summary.Replace("</p>", "");                 var values = summary.Split(                     new string[] { "<p>" },                     StringSplitOptions.RemoveEmptyEntries);                   if ( values.Length == 3 )                 {                     var times = values[1].Split(                         new string[] { "<br>" },                         StringSplitOptions.RemoveEmptyEntries);                       if ( times.Length > 0 )                     {                         utcTime = times[0];                     }                     if ( times.Length > 1 )                     {                         localTime = times[1];                     }                       depthDesc = values[2];                     depthDesc = "Depth: " + depthDesc.Substring(depthDesc.IndexOf(":") + 2);                 }             }               if ( latitude != null && longitude != null )             {                 quake = new Earthquake()                 {                     Id = entry.Id,                     Title = entry.Title.Text,                     Summary = entry.Summary.Text,                     Date = entry.LastUpdatedTime.DateTime,                     Url = entry.Links.Select(l => Path.Combine(l.BaseUri.OriginalString,                         l.Uri.OriginalString)).FirstOrDefault(),                     Age = entry.Categories.Where(c => c.Label == "Age")                         .Select(c => c.Name).FirstOrDefault(),                     Magnitude = magnitude.GetValueOrDefault(),                     Latitude = latitude.GetValueOrDefault(),                     Longitude = longitude.GetValueOrDefault(),                     DepthInKm = depthKm.GetValueOrDefault(),                     DepthDesc = depthDesc,                     UtcTime = utcTime,                     LocalTime = localTime                 };             }               return quake;         }           private T GetElementValue<T>(SyndicationItem entry, String name)         {             var el = entry.ElementExtensions.Where(e => e.OuterName == name).FirstOrDefault();             T value = default(T);               if ( el != null )             {                 value = el.GetObject<T>();             }               return value;         }           private double? TryParse(String value)         {             double d;             if ( Double.TryParse(value, out d) )             {                 return d;             }             return null;         }           /// <summary>         /// Gets the feed at the specified URL.         /// </summary>         /// <param name="url">The URL.</param>         /// <returns>A <see cref="SyndicationFeed"/> object.</returns>         public static SyndicationFeed GetFeed(String url)         {             SyndicationFeed feed = null;               try             {                 log.Debug("Loading RSS feed: " + url);                   using ( var reader = XmlReader.Create(url) )                 {                     feed = SyndicationFeed.Load(reader);                 }             }             catch ( Exception ex )             {                 log.Error("Error occurred while loading RSS feed: " + url, ex);             }               return feed;         }     } }   The only method that will be generated in the client side proxy class, EarthquakeContext, will be the GetEarthquakes() method. The reason being that it is the only public instance method and it returns an IQueryable<Earthquake> collection that can be consumed by the client application. GetEarthquakes() calls the static GetFeed(String) method, which utilizes the built in SyndicationFeed API to load the external data feed. You will need to add a reference to the System.ServiceModel.Web library in order to take advantage of the RSS/Atom reader. The API will also allow you to create your own feeds to serve up in your applications. Model I have also created a Model folder and added a new class, Earthquake.cs. The Earthquake object will hold the various properties returned from the Atom feed. Here is a sample of the code for that class. Notice the [Key] attribute on the Id property, which is required by RIA Services to uniquely identify the entity. using System; using System.Collections.Generic; using System.Linq; using System.Runtime.Serialization; using System.ComponentModel.DataAnnotations;   namespace EarthquakeLocator.Web.Model {     /// <summary>     /// Represents an earthquake occurrence and related information.     /// </summary>     [DataContract]     public class Earthquake     {         /// <summary>         /// Gets or sets the id.         /// </summary>         /// <value>The id.</value>         [Key]         [DataMember]         public string Id { get; set; }           /// <summary>         /// Gets or sets the title.         /// </summary>         /// <value>The title.</value>         [DataMember]         public string Title { get; set; }           /// <summary>         /// Gets or sets the summary.         /// </summary>         /// <value>The summary.</value>         [DataMember]         public string Summary { get; set; }           // additional properties omitted     } }   View Model The recent trend to use the MVVM pattern for WPF and Silverlight provides a great way to separate the data and behavior logic out of the user interface layer of your client applications. I have chosen to use the MVVM Light Toolkit for the Earthquake Locator, but there are other options out there if you prefer another library. That said, I went ahead and created a ViewModel folder in the Silverlight project and added a EarthquakeViewModel class that derives from ViewModelBase. Here is the code: using System; using System.Collections.ObjectModel; using System.ComponentModel.Composition; using System.ComponentModel.Composition.Hosting; using Microsoft.Maps.MapControl; using GalaSoft.MvvmLight; using EarthquakeLocator.Web.Model; using EarthquakeLocator.Web.Services;   namespace EarthquakeLocator.ViewModel {     /// <summary>     /// Provides data for views displaying earthquake information.     /// </summary>     public class EarthquakeViewModel : ViewModelBase     {         [Import]         public EarthquakeContext Context;           /// <summary>         /// Initializes a new instance of the <see cref="EarthquakeViewModel"/> class.         /// </summary>         public EarthquakeViewModel()         {             var catalog = new AssemblyCatalog(GetType().Assembly);             var container = new CompositionContainer(catalog);             container.ComposeParts(this);             Initialize();         }           /// <summary>         /// Initializes a new instance of the <see cref="EarthquakeViewModel"/> class.         /// </summary>         /// <param name="context">The context.</param>         public EarthquakeViewModel(EarthquakeContext context)         {             Context = context;             Initialize();         }           private void Initialize()         {             MapCenter = new Location(20, -170);             ZoomLevel = 2;         }           #region Private Methods           private void OnAutoLoadDataChanged()         {             LoadEarthquakes();         }           private void LoadEarthquakes()         {             var query = Context.GetEarthquakesQuery();             Context.Earthquakes.Clear();               Context.Load(query, (op) =>             {                 if ( !op.HasError )                 {                     foreach ( var item in op.Entities )                     {                         Earthquakes.Add(item);                     }                 }             }, null);         }           #endregion Private Methods           #region Properties           private bool autoLoadData;         /// <summary>         /// Gets or sets a value indicating whether to auto load data.         /// </summary>         /// <value><c>true</c> if auto loading data; otherwise, <c>false</c>.</value>         public bool AutoLoadData         {             get { return autoLoadData; }             set             {                 if ( autoLoadData != value )                 {                     autoLoadData = value;                     RaisePropertyChanged("AutoLoadData");                     OnAutoLoadDataChanged();                 }             }         }           private ObservableCollection<Earthquake> earthquakes;         /// <summary>         /// Gets the collection of earthquakes to display.         /// </summary>         /// <value>The collection of earthquakes.</value>         public ObservableCollection<Earthquake> Earthquakes         {             get             {                 if ( earthquakes == null )                 {                     earthquakes = new ObservableCollection<Earthquake>();                 }                   return earthquakes;             }         }           private Location mapCenter;         /// <summary>         /// Gets or sets the map center.         /// </summary>         /// <value>The map center.</value>         public Location MapCenter         {             get { return mapCenter; }             set             {                 if ( mapCenter != value )                 {                     mapCenter = value;                     RaisePropertyChanged("MapCenter");                 }             }         }           private double zoomLevel;         /// <summary>         /// Gets or sets the zoom level.         /// </summary>         /// <value>The zoom level.</value>         public double ZoomLevel         {             get { return zoomLevel; }             set             {                 if ( zoomLevel != value )                 {                     zoomLevel = value;                     RaisePropertyChanged("ZoomLevel");                 }             }         }           #endregion Properties     } }   The EarthquakeViewModel class contains all of the properties that will be bound to by the various controls in our views. Be sure to read through the LoadEarthquakes() method, which handles calling the GetEarthquakes() method in our EarthquakeService via the EarthquakeContext proxy, and also transfers the loaded entities into the view model’s Earthquakes collection. Another thing to notice is what’s going on in the default constructor. I chose to use the Managed Extensibility Framework (MEF) for my composition needs, but you can use any dependency injection library or none at all. To allow the EarthquakeContext class to be discoverable by MEF, I added the following partial class so that I could supply the appropriate [Export] attribute: using System; using System.ComponentModel.Composition;   namespace EarthquakeLocator.Web.Services {     /// <summary>     /// The client side proxy for the EarthquakeService class.     /// </summary>     [Export]     public partial class EarthquakeContext     {     } }   One last piece I wanted to point out before moving on to the user interface, I added a client side partial class for the Earthquake entity that contains helper properties that we will bind to later: using System;   namespace EarthquakeLocator.Web.Model {     /// <summary>     /// Represents an earthquake occurrence and related information.     /// </summary>     public partial class Earthquake     {         /// <summary>         /// Gets the location based on the current Latitude/Longitude.         /// </summary>         /// <value>The location.</value>         public string Location         {             get { return String.Format("{0},{1}", Latitude, Longitude); }         }           /// <summary>         /// Gets the size based on the Magnitude.         /// </summary>         /// <value>The size.</value>         public double Size         {             get { return (Magnitude * 3); }         }     } }   View Now the fun part! Usually, I would create a Views folder to place all of my View controls in, but I took the easy way out and added the following XAML code to the default MainPage.xaml file. Be sure to add the bing prefix associating the Microsoft.Maps.MapControl namespace after adding the assembly reference to your project. The MVVM Light Toolkit project templates come with a ViewModelLocator class that you can use via a static resource, but I am instantiating the EarthquakeViewModel directly in my user control. I am setting the AutoLoadData property to true as a way to trigger the LoadEarthquakes() method call. The MapItemsControl found within the <bing:Map> control binds its ItemsSource property to the Earthquakes collection of the view model, and since it is an ObservableCollection<T>, we get the automatic two way data binding via the INotifyCollectionChanged interface. <UserControl x:Class="EarthquakeLocator.MainPage"     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"     xmlns:bing="clr-namespace:Microsoft.Maps.MapControl;assembly=Microsoft.Maps.MapControl"     xmlns:vm="clr-namespace:EarthquakeLocator.ViewModel"     mc:Ignorable="d" d:DesignWidth="640" d:DesignHeight="480" >     <UserControl.Resources>         <DataTemplate x:Key="EarthquakeTemplate">             <Ellipse Fill="Red" Stroke="Black" StrokeThickness="1"                      Width="{Binding Size}" Height="{Binding Size}"                      bing:MapLayer.Position="{Binding Location}"                      bing:MapLayer.PositionOrigin="Center">                 <ToolTipService.ToolTip>                     <StackPanel>                         <TextBlock Text="{Binding Title}" FontSize="14" FontWeight="Bold" />                         <TextBlock Text="{Binding UtcTime}" />                         <TextBlock Text="{Binding LocalTime}" />                         <TextBlock Text="{Binding DepthDesc}" />                     </StackPanel>                 </ToolTipService.ToolTip>             </Ellipse>         </DataTemplate>     </UserControl.Resources>       <UserControl.DataContext>         <vm:EarthquakeViewModel AutoLoadData="True" />     </UserControl.DataContext>       <Grid x:Name="LayoutRoot">           <bing:Map x:Name="map" CredentialsProvider="--Your-Bing-Maps-Key--"                   Center="{Binding MapCenter, Mode=TwoWay}"                   ZoomLevel="{Binding ZoomLevel, Mode=TwoWay}">             <bing:MapItemsControl ItemsSource="{Binding Earthquakes}"                                   ItemTemplate="{StaticResource EarthquakeTemplate}" />         </bing:Map>       </Grid> </UserControl>   The EarthquakeTemplate defines the Ellipse that will represent each earthquake, the Width and Height that are determined by the Magnitude, the Position on the map, and also the tooltip that will appear when we mouse over each data point. Running the application will give us the following result (shown with a tooltip example): That concludes this portion of our show but I plan on implementing additional functionality in later blog posts. Be sure to come back soon to see the next installments in this series. Enjoy!   Additional Resources USGS Earthquake Data Feeds Brad Abrams shows how RIA Services and MVVM can work together

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  • The Incremental Architect&rsquo;s Napkin - #5 - Design functions for extensibility and readability

    - by Ralf Westphal
    Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/08/24/the-incremental-architectrsquos-napkin---5---design-functions-for.aspx The functionality of programs is entered via Entry Points. So what we´re talking about when designing software is a bunch of functions handling the requests represented by and flowing in through those Entry Points. Designing software thus consists of at least three phases: Analyzing the requirements to find the Entry Points and their signatures Designing the functionality to be executed when those Entry Points get triggered Implementing the functionality according to the design aka coding I presume, you´re familiar with phase 1 in some way. And I guess you´re proficient in implementing functionality in some programming language. But in my experience developers in general are not experienced in going through an explicit phase 2. “Designing functionality? What´s that supposed to mean?” you might already have thought. Here´s my definition: To design functionality (or functional design for short) means thinking about… well, functions. You find a solution for what´s supposed to happen when an Entry Point gets triggered in terms of functions. A conceptual solution that is, because those functions only exist in your head (or on paper) during this phase. But you may have guess that, because it´s “design” not “coding”. And here is, what functional design is not: It´s not about logic. Logic is expressions (e.g. +, -, && etc.) and control statements (e.g. if, switch, for, while etc.). Also I consider calling external APIs as logic. It´s equally basic. It´s what code needs to do in order to deliver some functionality or quality. Logic is what´s doing that needs to be done by software. Transformations are either done through expressions or API-calls. And then there is alternative control flow depending on the result of some expression. Basically it´s just jumps in Assembler, sometimes to go forward (if, switch), sometimes to go backward (for, while, do). But calling your own function is not logic. It´s not necessary to produce any outcome. Functionality is not enhanced by adding functions (subroutine calls) to your code. Nor is quality increased by adding functions. No performance gain, no higher scalability etc. through functions. Functions are not relevant to functionality. Strange, isn´t it. What they are important for is security of investment. By introducing functions into our code we can become more productive (re-use) and can increase evolvability (higher unterstandability, easier to keep code consistent). That´s no small feat, however. Evolvable code can hardly be overestimated. That´s why to me functional design is so important. It´s at the core of software development. To sum this up: Functional design is on a level of abstraction above (!) logical design or algorithmic design. Functional design is only done until you get to a point where each function is so simple you are very confident you can easily code it. Functional design an logical design (which mostly is coding, but can also be done using pseudo code or flow charts) are complementary. Software needs both. If you start coding right away you end up in a tangled mess very quickly. Then you need back out through refactoring. Functional design on the other hand is bloodless without actual code. It´s just a theory with no experiments to prove it. But how to do functional design? An example of functional design Let´s assume a program to de-duplicate strings. The user enters a number of strings separated by commas, e.g. a, b, a, c, d, b, e, c, a. And the program is supposed to clear this list of all doubles, e.g. a, b, c, d, e. There is only one Entry Point to this program: the user triggers the de-duplication by starting the program with the string list on the command line C:\>deduplicate "a, b, a, c, d, b, e, c, a" a, b, c, d, e …or by clicking on a GUI button. This leads to the Entry Point function to get called. It´s the program´s main function in case of the batch version or a button click event handler in the GUI version. That´s the physical Entry Point so to speak. It´s inevitable. What then happens is a three step process: Transform the input data from the user into a request. Call the request handler. Transform the output of the request handler into a tangible result for the user. Or to phrase it a bit more generally: Accept input. Transform input into output. Present output. This does not mean any of these steps requires a lot of effort. Maybe it´s just one line of code to accomplish it. Nevertheless it´s a distinct step in doing the processing behind an Entry Point. Call it an aspect or a responsibility - and you will realize it most likely deserves a function of its own to satisfy the Single Responsibility Principle (SRP). Interestingly the above list of steps is already functional design. There is no logic, but nevertheless the solution is described - albeit on a higher level of abstraction than you might have done yourself. But it´s still on a meta-level. The application to the domain at hand is easy, though: Accept string list from command line De-duplicate Present de-duplicated strings on standard output And this concrete list of processing steps can easily be transformed into code:static void Main(string[] args) { var input = Accept_string_list(args); var output = Deduplicate(input); Present_deduplicated_string_list(output); } Instead of a big problem there are three much smaller problems now. If you think each of those is trivial to implement, then go for it. You can stop the functional design at this point. But maybe, just maybe, you´re not so sure how to go about with the de-duplication for example. Then just implement what´s easy right now, e.g.private static string Accept_string_list(string[] args) { return args[0]; } private static void Present_deduplicated_string_list( string[] output) { var line = string.Join(", ", output); Console.WriteLine(line); } Accept_string_list() contains logic in the form of an API-call. Present_deduplicated_string_list() contains logic in the form of an expression and an API-call. And then repeat the functional design for the remaining processing step. What´s left is the domain logic: de-duplicating a list of strings. How should that be done? Without any logic at our disposal during functional design you´re left with just functions. So which functions could make up the de-duplication? Here´s a suggestion: De-duplicate Parse the input string into a true list of strings. Register each string in a dictionary/map/set. That way duplicates get cast away. Transform the data structure into a list of unique strings. Processing step 2 obviously was the core of the solution. That´s where real creativity was needed. That´s the core of the domain. But now after this refinement the implementation of each step is easy again:private static string[] Parse_string_list(string input) { return input.Split(',') .Select(s => s.Trim()) .ToArray(); } private static Dictionary<string,object> Compile_unique_strings(string[] strings) { return strings.Aggregate( new Dictionary<string, object>(), (agg, s) => { agg[s] = null; return agg; }); } private static string[] Serialize_unique_strings( Dictionary<string,object> dict) { return dict.Keys.ToArray(); } With these three additional functions Main() now looks like this:static void Main(string[] args) { var input = Accept_string_list(args); var strings = Parse_string_list(input); var dict = Compile_unique_strings(strings); var output = Serialize_unique_strings(dict); Present_deduplicated_string_list(output); } I think that´s very understandable code: just read it from top to bottom and you know how the solution to the problem works. It´s a mirror image of the initial design: Accept string list from command line Parse the input string into a true list of strings. Register each string in a dictionary/map/set. That way duplicates get cast away. Transform the data structure into a list of unique strings. Present de-duplicated strings on standard output You can even re-generate the design by just looking at the code. Code and functional design thus are always in sync - if you follow some simple rules. But about that later. And as a bonus: all the functions making up the process are small - which means easy to understand, too. So much for an initial concrete example. Now it´s time for some theory. Because there is method to this madness ;-) The above has only scratched the surface. Introducing Flow Design Functional design starts with a given function, the Entry Point. Its goal is to describe the behavior of the program when the Entry Point is triggered using a process, not an algorithm. An algorithm consists of logic, a process on the other hand consists just of steps or stages. Each processing step transforms input into output or a side effect. Also it might access resources, e.g. a printer, a database, or just memory. Processing steps thus can rely on state of some sort. This is different from Functional Programming, where functions are supposed to not be stateful and not cause side effects.[1] In its simplest form a process can be written as a bullet point list of steps, e.g. Get data from user Output result to user Transform data Parse data Map result for output Such a compilation of steps - possibly on different levels of abstraction - often is the first artifact of functional design. It can be generated by a team in an initial design brainstorming. Next comes ordering the steps. What should happen first, what next etc.? Get data from user Parse data Transform data Map result for output Output result to user That´s great for a start into functional design. It´s better than starting to code right away on a given function using TDD. Please get me right: TDD is a valuable practice. But it can be unnecessarily hard if the scope of a functionn is too large. But how do you know beforehand without investing some thinking? And how to do this thinking in a systematic fashion? My recommendation: For any given function you´re supposed to implement first do a functional design. Then, once you´re confident you know the processing steps - which are pretty small - refine and code them using TDD. You´ll see that´s much, much easier - and leads to cleaner code right away. For more information on this approach I call “Informed TDD” read my book of the same title. Thinking before coding is smart. And writing down the solution as a bunch of functions possibly is the simplest thing you can do, I´d say. It´s more according to the KISS (Keep It Simple, Stupid) principle than returning constants or other trivial stuff TDD development often is started with. So far so good. A simple ordered list of processing steps will do to start with functional design. As shown in the above example such steps can easily be translated into functions. Moving from design to coding thus is simple. However, such a list does not scale. Processing is not always that simple to be captured in a list. And then the list is just text. Again. Like code. That means the design is lacking visuality. Textual representations need more parsing by your brain than visual representations. Plus they are limited in their “dimensionality”: text just has one dimension, it´s sequential. Alternatives and parallelism are hard to encode in text. In addition the functional design using numbered lists lacks data. It´s not visible what´s the input, output, and state of the processing steps. That´s why functional design should be done using a lightweight visual notation. No tool is necessary to draw such designs. Use pen and paper; a flipchart, a whiteboard, or even a napkin is sufficient. Visualizing processes The building block of the functional design notation is a functional unit. I mostly draw it like this: Something is done, it´s clear what goes in, it´s clear what comes out, and it´s clear what the processing step requires in terms of state or hardware. Whenever input flows into a functional unit it gets processed and output is produced and/or a side effect occurs. Flowing data is the driver of something happening. That´s why I call this approach to functional design Flow Design. It´s about data flow instead of control flow. Control flow like in algorithms is of no concern to functional design. Thinking about control flow simply is too low level. Once you start with control flow you easily get bogged down by tons of details. That´s what you want to avoid during design. Design is supposed to be quick, broad brush, abstract. It should give overview. But what about all the details? As Robert C. Martin rightly said: “Programming is abot detail”. Detail is a matter of code. Once you start coding the processing steps you designed you can worry about all the detail you want. Functional design does not eliminate all the nitty gritty. It just postpones tackling them. To me that´s also an example of the SRP. Function design has the responsibility to come up with a solution to a problem posed by a single function (Entry Point). And later coding has the responsibility to implement the solution down to the last detail (i.e. statement, API-call). TDD unfortunately mixes both responsibilities. It´s just coding - and thereby trying to find detailed implementations (green phase) plus getting the design right (refactoring). To me that´s one reason why TDD has failed to deliver on its promise for many developers. Using functional units as building blocks of functional design processes can be depicted very easily. Here´s the initial process for the example problem: For each processing step draw a functional unit and label it. Choose a verb or an “action phrase” as a label, not a noun. Functional design is about activities, not state or structure. Then make the output of an upstream step the input of a downstream step. Finally think about the data that should flow between the functional units. Write the data above the arrows connecting the functional units in the direction of the data flow. Enclose the data description in brackets. That way you can clearly see if all flows have already been specified. Empty brackets mean “no data is flowing”, but nevertheless a signal is sent. A name like “list” or “strings” in brackets describes the data content. Use lower case labels for that purpose. A name starting with an upper case letter like “String” or “Customer” on the other hand signifies a data type. If you like, you also can combine descriptions with data types by separating them with a colon, e.g. (list:string) or (strings:string[]). But these are just suggestions from my practice with Flow Design. You can do it differently, if you like. Just be sure to be consistent. Flows wired-up in this manner I call one-dimensional (1D). Each functional unit just has one input and/or one output. A functional unit without an output is possible. It´s like a black hole sucking up input without producing any output. Instead it produces side effects. A functional unit without an input, though, does make much sense. When should it start to work? What´s the trigger? That´s why in the above process even the first processing step has an input. If you like, view such 1D-flows as pipelines. Data is flowing through them from left to right. But as you can see, it´s not always the same data. It get´s transformed along its passage: (args) becomes a (list) which is turned into (strings). The Principle of Mutual Oblivion A very characteristic trait of flows put together from function units is: no functional units knows another one. They are all completely independent of each other. Functional units don´t know where their input is coming from (or even when it´s gonna arrive). They just specify a range of values they can process. And they promise a certain behavior upon input arriving. Also they don´t know where their output is going. They just produce it in their own time independent of other functional units. That means at least conceptually all functional units work in parallel. Functional units don´t know their “deployment context”. They now nothing about the overall flow they are place in. They are just consuming input from some upstream, and producing output for some downstream. That makes functional units very easy to test. At least as long as they don´t depend on state or resources. I call this the Principle of Mutual Oblivion (PoMO). Functional units are oblivious of others as well as an overall context/purpose. They are just parts of a whole focused on a single responsibility. How the whole is built, how a larger goal is achieved, is of no concern to the single functional units. By building software in such a manner, functional design interestingly follows nature. Nature´s building blocks for organisms also follow the PoMO. The cells forming your body do not know each other. Take a nerve cell “controlling” a muscle cell for example:[2] The nerve cell does not know anything about muscle cells, let alone the specific muscel cell it is “attached to”. Likewise the muscle cell does not know anything about nerve cells, let a lone a specific nerve cell “attached to” it. Saying “the nerve cell is controlling the muscle cell” thus only makes sense when viewing both from the outside. “Control” is a concept of the whole, not of its parts. Control is created by wiring-up parts in a certain way. Both cells are mutually oblivious. Both just follow a contract. One produces Acetylcholine (ACh) as output, the other consumes ACh as input. Where the ACh is going, where it´s coming from neither cell cares about. Million years of evolution have led to this kind of division of labor. And million years of evolution have produced organism designs (DNA) which lead to the production of these different cell types (and many others) and also to their co-location. The result: the overall behavior of an organism. How and why this happened in nature is a mystery. For our software, though, it´s clear: functional and quality requirements needs to be fulfilled. So we as developers have to become “intelligent designers” of “software cells” which we put together to form a “software organism” which responds in satisfying ways to triggers from it´s environment. My bet is: If nature gets complex organisms working by following the PoMO, who are we to not apply this recipe for success to our much simpler “machines”? So my rule is: Wherever there is functionality to be delivered, because there is a clear Entry Point into software, design the functionality like nature would do it. Build it from mutually oblivious functional units. That´s what Flow Design is about. In that way it´s even universal, I´d say. Its notation can also be applied to biology: Never mind labeling the functional units with nouns. That´s ok in Flow Design. You´ll do that occassionally for functional units on a higher level of abstraction or when their purpose is close to hardware. Getting a cockroach to roam your bedroom takes 1,000,000 nerve cells (neurons). Getting the de-duplication program to do its job just takes 5 “software cells” (functional units). Both, though, follow the same basic principle. Translating functional units into code Moving from functional design to code is no rocket science. In fact it´s straightforward. There are two simple rules: Translate an input port to a function. Translate an output port either to a return statement in that function or to a function pointer visible to that function. The simplest translation of a functional unit is a function. That´s what you saw in the above example. Functions are mutually oblivious. That why Functional Programming likes them so much. It makes them composable. Which is the reason, nature works according to the PoMO. Let´s be clear about one thing: There is no dependency injection in nature. For all of an organism´s complexity no DI container is used. Behavior is the result of smooth cooperation between mutually oblivious building blocks. Functions will often be the adequate translation for the functional units in your designs. But not always. Take for example the case, where a processing step should not always produce an output. Maybe the purpose is to filter input. Here the functional unit consumes words and produces words. But it does not pass along every word flowing in. Some words are swallowed. Think of a spell checker. It probably should not check acronyms for correctness. There are too many of them. Or words with no more than two letters. Such words are called “stop words”. In the above picture the optionality of the output is signified by the astrisk outside the brackets. It means: Any number of (word) data items can flow from the functional unit for each input data item. It might be none or one or even more. This I call a stream of data. Such behavior cannot be translated into a function where output is generated with return. Because a function always needs to return a value. So the output port is translated into a function pointer or continuation which gets passed to the subroutine when called:[3]void filter_stop_words( string word, Action<string> onNoStopWord) { if (...check if not a stop word...) onNoStopWord(word); } If you want to be nitpicky you might call such a function pointer parameter an injection. And technically you´re right. Conceptually, though, it´s not an injection. Because the subroutine is not functionally dependent on the continuation. Firstly continuations are procedures, i.e. subroutines without a return type. Remember: Flow Design is about unidirectional data flow. Secondly the name of the formal parameter is chosen in a way as to not assume anything about downstream processing steps. onNoStopWord describes a situation (or event) within the functional unit only. Translating output ports into function pointers helps keeping functional units mutually oblivious in cases where output is optional or produced asynchronically. Either pass the function pointer to the function upon call. Or make it global by putting it on the encompassing class. Then it´s called an event. In C# that´s even an explicit feature.class Filter { public void filter_stop_words( string word) { if (...check if not a stop word...) onNoStopWord(word); } public event Action<string> onNoStopWord; } When to use a continuation and when to use an event dependens on how a functional unit is used in flows and how it´s packed together with others into classes. You´ll see examples further down the Flow Design road. Another example of 1D functional design Let´s see Flow Design once more in action using the visual notation. How about the famous word wrap kata? Robert C. Martin has posted a much cited solution including an extensive reasoning behind his TDD approach. So maybe you want to compare it to Flow Design. The function signature given is:string WordWrap(string text, int maxLineLength) {...} That´s not an Entry Point since we don´t see an application with an environment and users. Nevertheless it´s a function which is supposed to provide a certain functionality. The text passed in has to be reformatted. The input is a single line of arbitrary length consisting of words separated by spaces. The output should consist of one or more lines of a maximum length specified. If a word is longer than a the maximum line length it can be split in multiple parts each fitting in a line. Flow Design Let´s start by brainstorming the process to accomplish the feat of reformatting the text. What´s needed? Words need to be assembled into lines Words need to be extracted from the input text The resulting lines need to be assembled into the output text Words too long to fit in a line need to be split Does sound about right? I guess so. And it shows a kind of priority. Long words are a special case. So maybe there is a hint for an incremental design here. First let´s tackle “average words” (words not longer than a line). Here´s the Flow Design for this increment: The the first three bullet points turned into functional units with explicit data added. As the signature requires a text is transformed into another text. See the input of the first functional unit and the output of the last functional unit. In between no text flows, but words and lines. That´s good to see because thereby the domain is clearly represented in the design. The requirements are talking about words and lines and here they are. But note the asterisk! It´s not outside the brackets but inside. That means it´s not a stream of words or lines, but lists or sequences. For each text a sequence of words is output. For each sequence of words a sequence of lines is produced. The asterisk is used to abstract from the concrete implementation. Like with streams. Whether the list of words gets implemented as an array or an IEnumerable is not important during design. It´s an implementation detail. Does any processing step require further refinement? I don´t think so. They all look pretty “atomic” to me. And if not… I can always backtrack and refine a process step using functional design later once I´ve gained more insight into a sub-problem. Implementation The implementation is straightforward as you can imagine. The processing steps can all be translated into functions. Each can be tested easily and separately. Each has a focused responsibility. And the process flow becomes just a sequence of function calls: Easy to understand. It clearly states how word wrapping works - on a high level of abstraction. And it´s easy to evolve as you´ll see. Flow Design - Increment 2 So far only texts consisting of “average words” are wrapped correctly. Words not fitting in a line will result in lines too long. Wrapping long words is a feature of the requested functionality. Whether it´s there or not makes a difference to the user. To quickly get feedback I decided to first implement a solution without this feature. But now it´s time to add it to deliver the full scope. Fortunately Flow Design automatically leads to code following the Open Closed Principle (OCP). It´s easy to extend it - instead of changing well tested code. How´s that possible? Flow Design allows for extension of functionality by inserting functional units into the flow. That way existing functional units need not be changed. The data flow arrow between functional units is a natural extension point. No need to resort to the Strategy Pattern. No need to think ahead where extions might need to be made in the future. I just “phase in” the remaining processing step: Since neither Extract words nor Reformat know of their environment neither needs to be touched due to the “detour”. The new processing step accepts the output of the existing upstream step and produces data compatible with the existing downstream step. Implementation - Increment 2 A trivial implementation checking the assumption if this works does not do anything to split long words. The input is just passed on: Note how clean WordWrap() stays. The solution is easy to understand. A developer looking at this code sometime in the future, when a new feature needs to be build in, quickly sees how long words are dealt with. Compare this to Robert C. Martin´s solution:[4] How does this solution handle long words? Long words are not even part of the domain language present in the code. At least I need considerable time to understand the approach. Admittedly the Flow Design solution with the full implementation of long word splitting is longer than Robert C. Martin´s. At least it seems. Because his solution does not cover all the “word wrap situations” the Flow Design solution handles. Some lines would need to be added to be on par, I guess. But even then… Is a difference in LOC that important as long as it´s in the same ball park? I value understandability and openness for extension higher than saving on the last line of code. Simplicity is not just less code, it´s also clarity in design. But don´t take my word for it. Try Flow Design on larger problems and compare for yourself. What´s the easier, more straightforward way to clean code? And keep in mind: You ain´t seen all yet ;-) There´s more to Flow Design than described in this chapter. In closing I hope I was able to give you a impression of functional design that makes you hungry for more. To me it´s an inevitable step in software development. Jumping from requirements to code does not scale. And it leads to dirty code all to quickly. Some thought should be invested first. Where there is a clear Entry Point visible, it´s functionality should be designed using data flows. Because with data flows abstraction is possible. For more background on why that´s necessary read my blog article here. For now let me point out to you - if you haven´t already noticed - that Flow Design is a general purpose declarative language. It´s “programming by intention” (Shalloway et al.). Just write down how you think the solution should work on a high level of abstraction. This breaks down a large problem in smaller problems. And by following the PoMO the solutions to those smaller problems are independent of each other. So they are easy to test. Or you could even think about getting them implemented in parallel by different team members. Flow Design not only increases evolvability, but also helps becoming more productive. All team members can participate in functional design. This goes beyon collective code ownership. We´re talking collective design/architecture ownership. Because with Flow Design there is a common visual language to talk about functional design - which is the foundation for all other design activities.   PS: If you like what you read, consider getting my ebook “The Incremental Architekt´s Napkin”. It´s where I compile all the articles in this series for easier reading. I like the strictness of Function Programming - but I also find it quite hard to live by. And it certainly is not what millions of programmers are used to. Also to me it seems, the real world is full of state and side effects. So why give them such a bad image? That´s why functional design takes a more pragmatic approach. State and side effects are ok for processing steps - but be sure to follow the SRP. Don´t put too much of it into a single processing step. ? Image taken from www.physioweb.org ? My code samples are written in C#. C# sports typed function pointers called delegates. Action is such a function pointer type matching functions with signature void someName(T t). Other languages provide similar ways to work with functions as first class citizens - even Java now in version 8. I trust you find a way to map this detail of my translation to your favorite programming language. I know it works for Java, C++, Ruby, JavaScript, Python, Go. And if you´re using a Functional Programming language it´s of course a no brainer. ? Taken from his blog post “The Craftsman 62, The Dark Path”. ?

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  • How to create item in SharePoint2010 document library using SharePoint Web service

    - by ybbest
    Today, I’d like to show you how to create item in SharePoint2010 document library using SharePoint Web service. Originally, I thought I could use the WebSvcLists(list.asmx) that provides methods for working with lists and list data. However, after a bit Googling , I realize that I need to use the WebSvcCopy (copy.asmx).Here are the code used private const string siteUrl = "http://ybbest"; private static void Main(string[] args) { using (CopyWSProxyWrapper copyWSProxyWrapper = new CopyWSProxyWrapper(siteUrl)) { copyWSProxyWrapper.UploadFile("TestDoc2.pdf", new[] {string.Format("{0}/Shared Documents/TestDoc2.pdf", siteUrl)}, Resource.TestDoc, GetFieldInfos().ToArray()); } } private static List<FieldInformation> GetFieldInfos() { var fieldInfos = new List<FieldInformation>(); //The InternalName , DisplayName and FieldType are both required to make it work fieldInfos.Add(new FieldInformation { InternalName = "Title", Value = "TestDoc2.pdf", DisplayName = "Title", Type = FieldType.Text }); return fieldInfos; } Here is the code for the proxy wrapper. public class CopyWSProxyWrapper : IDisposable { private readonly string siteUrl; public CopyWSProxyWrapper(string siteUrl) { this.siteUrl = siteUrl; } private readonly CopySoapClient proxy = new CopySoapClient(); public void UploadFile(string testdoc2Pdf, string[] destinationUrls, byte[] testDoc, FieldInformation[] fieldInformations) { using (CopySoapClient proxy = new CopySoapClient()) { proxy.Endpoint.Address = new EndpointAddress(String.Format("{0}/_vti_bin/copy.asmx", siteUrl)); proxy.ClientCredentials.Windows.ClientCredential = CredentialCache.DefaultNetworkCredentials; proxy.ClientCredentials.Windows.AllowedImpersonationLevel = TokenImpersonationLevel.Impersonation; CopyResult[] copyResults = null; try { proxy.CopyIntoItems(testdoc2Pdf, destinationUrls, fieldInformations, testDoc, out copyResults); } catch (Exception e) { System.Console.WriteLine(e); } if (copyResults != null) System.Console.WriteLine(copyResults[0].ErrorMessage); System.Console.ReadLine(); } } public void Dispose() { proxy.Close(); } } You can download the source code here . ******Update********** It seems to be a bug that , you can not set the contentType when create a document item using Copy.asmx. In sp2007 the field type was Choice, however, in sp2010 it is actually Computed. I have tried using the Computed field type with no luck. I have also tried sending the ContentTypeId and this does not work.You might have to write your own web services to handle this.You can check my previous blog on how to get started with you own custom WCF in SP2010 here. References: SharePoint 2010 Web Services SharePoint2007 Web Services SharePoint MSDN Forum

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  • Challenge 19 – An Explanation of a Query

    - by Dave Ballantyne
    I have received a number of requests for an explanation of my winning query of TSQL Challenge 19. This involved traversing a hierarchy of employees and rolling a count of orders from subordinates up to superiors. The first concept I shall address is the hierarchyId , which is constructed within the CTE called cteTree.   cteTree is a recursive cte that will expand the parent-child hierarchy of the personnel in the table @emp.  One useful feature with a recursive cte is that data can be ‘passed’ from the parent to the child data.  The hierarchyId column is similar to the hierarchyId data type that was introduced in SQL Server 2008 and represents the position of the person within the organisation. Let us start with a simplistic example Albert manages Bob and Eddie.  Bob manages Carl and Dave. The hierarchyId will represent each person’s position in this relationship in a single field.  In this simple example we could append the userID together into a varchar field as detailed below. This will enable us to select a branch of the tree by filtering using Where hierarchyId  ‘1,2%’ to select Bob and all his subordinates.  Naturally, this is not comprehensive enough to provide a full solution, but as opposed to concatenating the Id’s together into a varchar datatyped column, we can apply the same theory to a varbinary.  By CASTing the ID’s into a datatype of varbinary(4) ,4 is used as 4 bytes of data are used to store an integer and building a hierarchyId  from those.  For example: The important point to bear in mind for later in the query is that the binary data generated is 'byte order comparable'. ie We can ORDER a dataset with it and the resulting data, will be in the order required. Now, would probably be a good time to download the example file and, after the cte ‘cteTree’, uncomment the line ‘select * from cteTree’.  Mark this and all prior code and execute.  This will show you how this theory directly relates to the actual challenge data.  The only deviation from the above, is that instead of using the ID of an employee, I have used the row_number() ranking function to order each level by LastName,Firstname.  This enables me to order by the HierarchyId in the final result set so that the result set is in the required order. Your output should be something like the below.  Notice also the ‘Level’ Column that contains the depth that the employee is within the tree.  I would encourage you to ‘play’ with the query, change the order in the row_number() or the length of the cast in the hierarchyId to see how that effects the outcome.  The next cte, ‘cteTreeWithOrderCount’, is a join between cteTree and the @ord table, and COUNT’s the number of orders per employee.  A LEFT JOIN is employed here to account for the occasion where an employee has made no sales.   Executing a ‘Select * from cteTreeWithOrderCount’ will return the result set as below.  The order here is unimportant as this is only a staging point of the data and only the final result set in a cte chain needs an Order by clause, unless TOP is utilised. cteExplode joins the above result set to the tally table (Nums) for Level Occurances.  So, if level is 2 then 2 rows are required.  This is done to expand the dataset, to create a new column (PathInc), which is the (n+1) integers contained within the heirarchyid.  For example, with the data for Robert King as given above, the below 3 rows will be returned. From this you can see that the pathinc column now contains the values for Andrew Fuller and Steven Buchanan who are Robert King’s superiors within the tree.    Finally cteSumUp, sums the orders for each person and their subordinates using the PathInc generated above, and the final select does the final simple mathematics and filters to restrict the result set to only the ‘original’ row per employee.

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