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  • Constructor Overloading

    - by Mark Baker
    Normally when I want to create a class constructor that accepts different types of parameters, I'll use a kludgy overloading principle of not defining any args in the constructor definition: e.g. for an ECEF coordinate class constructor, I want it to accept either $x, $y and $z arguments, or to accept a single array argument containg x, y and z values, or to accept a single LatLong object I'd create a constructor looking something like: function __construct() { // Identify if any arguments have been passed to the constructor if (func_num_args() > 0) { $args = func_get_args(); // Identify the overload constructor required, based on the datatype of the first argument $argType = gettype($args[0]); switch($argType) { case 'array' : // Array of Cartesian co-ordinate values $overloadConstructor = 'setCoordinatesFromArray'; break; case 'object' : // A LatLong object that needs converting to Cartesian co-ordinate values $overloadConstructor = 'setCoordinatesFromLatLong'; break; default : // Individual Cartesian co-ordinate values $overloadConstructor = 'setCoordinatesFromXYZ'; break; } // Call the appropriate overload constructor call_user_func_array(array($this,$overloadConstructor),$args); } } // function __construct() I'm looking at an alternative: to provide a straight constructor with $x, $y and $z as defined arguments, and to provide static methods of createECEFfromArray() and createECEFfromLatLong() that handle all the necessary extraction of x, y and z; then create a new ECEF object using the standard constructor, and return that Which option is cleaner from an OO purists perspective?

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  • What OOP pattern to use when only adding new methods, not data?

    - by Jonathon Reinhart
    Hello eveyone... In my app, I have deal with several different "parameters", which derive from IParameter interface, and also ParamBase abstract base class. I currently have two different parameter types, call them FooParameter and BarParameter, which both derive from ParamBase. Obviously, I can treat them both as IParameters when I need to deal with them generically, or detect their specific type when I need to handle their specific functionality. My question lies in specific FooParameters. I currently have a few specific ones with their own classes which derive from FooParameter, we'll call them FP12, FP13, FP14, etc. These all have certain characteristics, which make me treat them differently in the UI. (Most have names associated with the individual bits, or ranges of bits). Note that these specific, derived FP's have no additional data associated with them, only properties (which refer to the same data in different ways) or methods. Now, I'd like to keep all of these parameters in a Dictionary<String, IParameter> for easy generic access. The problem is, if I want to refer to a specific one with the special GUI functions, I can't write: FP12 fp12 = (FP12)paramList["FP12"] because you can't downcast to a derived type (rightfully so). But in my case, I didn't add any data, so the cast would theoretically work. What type of programming model should I be using instead? Thanks!

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  • Entity Framework: Auto-updating foreign key when setting a new object reference

    - by Adrian Grigore
    Hi, I am porting an existing application from Linq to SQL to Entity Framework 4 (default code generation). One difference I noticed between the two is that a foreign key property are not updated when resetting the object reference. Now I need to decide how to deal with this. For example supposing you have two entity types, Company and Employee. One Company has many Employees. In Linq To SQL, setting the company also sets the company id: var company=new Company(ID=1); var employee=new Employee(); Debug.Assert(employee.CompanyID==0); employee.Company=company; Debug.Assert(employee.CompanyID==1); //Works fine! In Entity Framework (and without using any code template customization) this does not work: var company=new Company(ID=1); var employee=new Employee(); Debug.Assert(employee.CompanyID==0); employee.Company=company; Debug.Assert(employee.CompanyID==1); //Throws, since CompanyID was not updated! How can I make EF behave the same way as LinqToSQL? I had a look at the default code generation T4 template, but I could not figure out how to make the necessary changes.

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  • Good data structure for efficient insert/querying on arbitrary properties

    - by Juliet
    I'm working on a project where Arrays are the default data structure for everything, and every query is a linear search in the form of: Need a customer with a particular name? customer.Find(x => x.Name == name) Need a customer with a particular unique id? customer.Find(x => x.Id == id) Need a customer of a particular type and age? customer.Find(x => x is PreferredCustomer && x.Age >= age) Need a customer of a particular name and age? customer.Find(x => x.Name == name && x.Age == age) In almost all instances, the criteria for lookups is well-defined. For example, we only search for customers by one or more of the properties Id, Type, Name, or Age. We rarely search by anything else. Is a good data structure to support arbitrary queries of these types with lookup better than O(n)? Any out-of-the-box implementations for .NET?

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  • How to update GUI thread/class from worker thread/class?

    - by user315182
    First question here so hello everyone. The requirement I'm working on is a small test application that communicates with an external device over a serial port. The communication can take a long time, and the device can return all sorts of errors. The device is nicely abstracted in its own class that the GUI thread starts to run in its own thread and has the usual open/close/read data/write data basic functions. The GUI is also pretty simple - choose COM port, open, close, show data read or errors from device, allow modification and write back etc. The question is simply how to update the GUI from the device class? There are several distinct types of data the device deals with so I need a relatively generic bridge between the GUI form/thread class and the working device class/thread. In the GUI to device direction everything works fine with [Begin]Invoke calls for open/close/read/write etc. on various GUI generated events. I've read the thread here (How to update GUI from another thread in C#?) where the assumption is made that the GUI and worker thread are in the same class. Google searches throw up how to create a delegate or how to create the classic background worker but that's not at all what I need, although they may be part of the solution. So, is there a simple but generic structure that can be used? My level of C# is moderate and I've been programming all my working life, given a clue I'll figure it out (and post back)... Thanks in advance for any help.

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  • Java Scanner newline parsing with regex (Bug?)

    - by SEK
    I'm developing a syntax analyzer by hand in Java, and I'd like to use regex's to parse the various token types. The problem is that I'd also like to be able to accurately report the current line number, if the input doesn't conform to the syntax. Long story short, I've run into a problem when I try to actually match a newline with the Scanner class. To be specific, when I try to match a newline with a pattern using the Scanner class, it fails. Almost always. But when I perform the same matching using a Matcher and the same source string, it retrieves the newline exactly as you'd expect it too. Is there a reason for this, that I can't seem to discover, or is this a bug, as I suspect? FYI: I was unable to find a bug in the Sun database that describes this issue, so if it is a bug, it hasn't been reported. Example Code: Pattern newLinePattern = Pattern.compile("(\\r\\n?|\\n)", Pattern.MULTILINE); String sourceString = "\r\n\n\r\r\n\n"; Scanner scan = new Scanner(sourceString); scan.useDelimiter(""); int count = 0; while (scan.hasNext(newLinePattern)) { scan.next(newLinePattern); count++; } System.out.println("found "+count+" newlines"); // finds 7 newlines Matcher match = newLinePattern.matcher(sourceString); count = 0; while (match.find()) { count++; } System.out.println("found "+count+" newlines"); // finds 5 newlines

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  • I need a fast runtime expression parser

    - by Chris Lively
    I need to locate a fast, lightweight expression parser. Ideally I want to pass it a list of name/value pairs (e.g. variables) and a string containing the expression to evaluate. All I need back from it is a true/false value. The types of expressions should be along the lines of: varA == "xyz" and varB==123 Basically, just a simple logic engine whose expression is provided at runtime. UPDATE At minimum it needs to support ==, !=, , =, <, <= Regarding speed, I expect roughly 5 expressions to be executed per request. We'll see somewhere in the vicinity of 100/requests a second. Our current pages tend to execute in under 50ms. Usually there will only be 2 or 3 variables involved in any expression. However, I'll need to load approximately 30 into the parser prior to execution. UPDATE 2012/11/5 Update about performance. We implemented nCalc nearly 2 years ago. Since then we've expanded it's use such that we average 40+ expressions covering 300+ variables on post backs. There are now thousands of post backs occurring per second with absolutely zero performance degradation. We've also extended it to include a handful of additional functions, again with no performance loss. In short, nCalc met all of our needs and exceeded our expectations.

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  • switching C compiler causes: Error Initializer cannot be specified for a flexible array member

    - by user1054210
    I am trying to convert our code from one IDE to be used in a different one. The current one uses gcc which allows for this structure to be initialized from a variable array. The new tool does not use gcc gives me an error "Initializer cannot be specified for a flexible array member". So can someone help me understand how to set this up? Should I set up a blank array of variable size and then somewhere assign the #define array as seen below? Here would be an example of the code…(this is current implementation current IDE) In one header file that is Build switchable so we can build this on different hardware platforms we have the following #define #define GPIOS \ /* BANK, PIN, SPD, MODE,… */ GPIOINIT( A, 0, 2, AIN, …) \ GPIOINIT( A, 1, 2, AIN, …) \ GPIOINTINIT(A, 2, 2, AIN, …) \ . . . Then in a different header file that is used in all builds we have PLATFORM_CONFIG_T g_platformConfig = { .name = {PLATFORM_NAME}, (bunch of other stuff), .allGpios = { GPIOS /* here I get the error */ }, }; So I am thinking I can make the error line a variable array and assign to it later in some other way? The problem is the actual array "GPIO" is of different types and pin orders on different designs are different.

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  • Full-text search in C++

    - by Jen
    I have a database of many (though relatively short) HTML documents. I want users to be able to search this database by entering one or more search words in a C++ desktop application. Hence, I’m looking for a fast full-text search solution. Ideally, it should: Skip common words, such as the, of, and, etc. Support stemming, i.e. search for run also finds documents containing runner, running and ran. Be able to update its index in the background as new documents are added to the database. Be able to provide search word suggestions (like Google Suggest) To illustrate, assume the database has just two documents: Document 1: This is a test of text search. Document 2: Testing is fun. The following words should be in the index: fun, search, test, testing, text. If the user types t in the search box, I want the application to be able to suggest test, testing and text (Ideally, the application should be able to query the search engine for the 10 most common search words starting with t). A search for testing should return both documents. Can you suggest a C or C++ based solution? (I’ve briefly reviewed CLucene and Xapian, but I’m not sure if either will address my needs, especially querying the search word indexes for the suggest feature).

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  • Comparing all properties of an object using expression trees

    - by stringargs
    Hi, I'm trying to write a simple generator that uses an expression tree to dynamically generate a method that compares all properties of an instance of a type to the properties of another instance of that type. This works fine for most properties, like int an string, but fails for DateTime? (and presumably other nullable value types). The method: static Delegate GenerateComparer(Type type) { var left = Expression.Parameter(type, "left"); var right = Expression.Parameter(type, "right"); Expression result = null; foreach (var p in type.GetProperties()) { var leftProperty = Expression.Property(left, p.Name); var rightProperty = Expression.Property(right, p.Name); var equals = p.PropertyType.GetMethod("Equals", new[] { p.PropertyType }); var callEqualsOnLeft = Expression.Call(leftProperty, equals, rightProperty); result = result != null ? (Expression)Expression.And(result, callEqualsOnLeft) : (Expression)callEqualsOnLeft; } var method = Expression.Lambda(result, left, right).Compile(); return method; } On a DateTime? property it fails with: Expression of type 'System.Nullable`1[System.DateTime]' cannot be used for parameter of type 'System.Object' of method 'Boolean Equals(System.Object)' OK, so it finds an overload of Equals that expects object. So why can't I pass a DateTime? into that, as it's convertible to object? If I look at Nullable<T>, it indeed has an override of Equals(object o). PS: I realize that this isn't a proper generator yet as it can't deal with null values, but I'll get to that :)

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  • Can't combine "LINQ Join" with other tables

    - by FullmetalBoy
    The main problem is that I recieve the following message: "base {System.SystemException} = {"Unable to create a constant value of type 'BokButik1.Models.Book-Author'. Only primitive types ('such as Int32, String, and Guid') are supported in this context."}" based on this LinQ code: IBookRepository myIBookRepository = new BookRepository(); var allBooks = myIBookRepository.HamtaAllaBocker(); IBok_ForfattareRepository myIBok_ForfattareRepository = new Bok_ForfattareRepository(); var Book-Authors = myIBok_ForfattareRepository.HamtaAllaBok_ForfattareNummer(); var q = from booknn in allBooks join Book-Authornn in Book-Authors on booknn.BookID equals Book-Authornn.BookID select new { booknn.title, Book-AuthorID }; How shall I solve this problem to get a class instance that contain with property title and Book-AuthorID? // Fullmetalboy I also have tried making some dummy by using "allbooks" relation with Code Samples from the address http://www.hookedonlinq.com/JoinOperator.ashx. Unfortunately, still same problem. I also have taken account to Int32 due to entity framework http://msdn.microsoft.com/en-us/library/bb896317.aspx. Unfortunatley, still same problem. Using database with 3 tables and one of them is a many to many relationship. This database is used in relation with entity framework Book-Author Book-Author (int) BookID (int) Forfattare (int) Book BookID (int) title (string) etc etc etc

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  • JAVA Procedure Error

    - by Sam....
    java.sql.SQLException: [Microsoft][SQLServer 2000 Driver for JDBC][SQLServer]Procedure 'STP_Insert_tblReceipt' expects parameter '@CPVFlag', which was not supplied. I m getting error at This Point when trying to call procedure... Everything is perfect ,,,Count of Question marks are similar to parameter provided cs = conn.prepareCall("{call STP_Insert_tblReceipt(?,?,?, ?,?,?, ?,?,?, ?,?,?, ?,?,?, ?,?,?, ?,?,?, ?,?,?, ?,?,?)}"); // cs = conn.prepareCall("{call STP_Receipt_Form_Insertion_Trial(?,?,?, ?,?,?, ?,?,?, ?,?,?, ?)}"); cs.setLong(1, Long.parseLong(txtMobileNo.getText())); cs.setString(2, String.valueOf(cboDistributor.getSelectedItem())); cs.setLong(3, Long.parseLong(txtBoxNo.getText())); cs.setInt(4, Integer.parseInt(txtFileNo.getText())); cs.setString(5, pickUp_date); cs.setString(6, rec_date); cs.setString(7, String.valueOf(cmbCtrlNo.getSelectedItem())); cs.setString(8, UserName); cs.setString(9, rec_date); cs.setString(10, RegionLocation); cs.setString(11, txtRemark.getText().trim()); cs.setString(12, txtSimNo.getText().trim()); cs.setInt(13, 2); cs.setString(14, String.valueOf(cmbAryanRegion.getSelectedItem())); cs.setString(15, String.valueOf(cboPickUpType.getSelectedItem())); cs.setString(16, String.valueOf(txtCafNo.getText())); cs.setString(17, distributorId); //cs.setString(18, circleName); cs.setString(18, cboCircle.getSelectedItem().toString()); cs.registerOutParameter(19, java.sql.Types.INTEGER); cs.setString(20, auditorName); cs.setString(21, retailerName); cs.setString(22, retailerCode); cs.setInt(23, mappedFlag); //cs.setString(24, distCode); cs.setString(24, cboDistCode.getSelectedItem().toString()); //cs.setString(25, zoneName); cs.setString(25, cboZone.getSelectedItem().toString()); cs.setString(26, comment); **cs.setInt(27, 1);** **this is for CPV Flag** After this cs.execute();

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  • SQL Server 2005 - Enabling both Named Pipes & TCP/IP protocols?

    - by Clinemi
    We have a SQL Server 2005 database, and currently all our users are connecting to the database via the TCP/IP protocol. The SQL Server Configuration Manager allows you to "enable" both Named Pipes, and TCP/IP connections at the same time. Is this a good idea? My question is not whether we should use named pipes instead of TCP/IP, but are there problems associated with enabling both? One of our client's IT guys, says that enabling database communication with both protocols will limit the bandwidth that either protocol can use - to like 50% of the total. I would think that the bandwidth that TCP/IP could use would be directly tied (inversely) to the amount of traffic that Named Pipes (or any of the other types of traffic) were occupying on the network at that moment. However, this IT person is indicating that the fact that we have enabled two protocols on the server, artificially limits the bandwidth that TCP/IP can use. Is this correct? I did Google searches but could not come up with an answer to this question. Any help would be appreciated.

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  • Is context:annotation-config an alternative to @AutoWired?

    - by Antacid
    Is it correct that I can put context:annotation-config in my XML config and it will automatically inject the bean class without needing any annotations? So instead of using these annotation types: public class Mailman { private String name; @Autowired private Parcel Parcel; public Mailman(String name) { this.name = name; } @Autowired public void setParcel(Parcel Parcel) { this.Parcel = Parcel; } @Autowired public void directionsToParcel(Parcel Parcel) { this.Parcel = Parcel; } } I would just need to write this: <beans ... > <bean id="mailMan" class="MailMan"> <constructor-arg value="John Doe"/> </bean> <bean id="parcel" class="Parcel" /> <context:annotation-config /> </beans> and then my MailMan class would look a lot simpler without the need for annotations: public class Mailman { private String name; private Parcel Parcel; public Mailman(String name) { this.name = name; } }

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  • Accept templated parameter of stl_container_type<string>::iterator

    - by Rodion Ingles
    I have a function where I have a container which holds strings (eg vector<string>, set<string>, list<string>) and, given a start iterator and an end iterator, go through the iterator range processing the strings. Currently the function is declared like this: template< typename ContainerIter> void ProcessStrings(ContainerIter begin, ContainerIter end); Now this will accept any type which conforms to the implicit interface of implementing operator*, prefix operator++ and whatever other calls are in the function body. What I really want to do is have a definition like the one below which explicitly restricts the amount of input (pseudocode warning): template< typename Container<string>::iterator> void ProcessStrings(Container<string>::iterator begin, Container<string>::iterator end); so that I can use it as such: vector<string> str_vec; list<string> str_list; set<SomeOtherClass> so_set; ProcessStrings(str_vec.begin(), str_vec.end()); // OK ProcessStrings(str_list.begin(), str_list.end()); //OK ProcessStrings(so_set.begin(), so_set.end()); // Error Essentially, what I am trying to do is restrict the function specification to make it obvious to a user of the function what it accepts and if the code fails to compile they get a message that they are using the wrong parameter types rather than something in the function body that XXX function could not be found for XXX class.

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  • Sending files from server to client in Java

    - by Lee Jacobson
    Hi, I'm trying to find a way to send files of different file types from a server to a client. I have this code on the server to put the file into a byte array: File file = new File(resourceLocation); byte[] b = new byte[(int) file.length()]; FileInputStream fileInputStream; try { fileInputStream = new FileInputStream(file); try { fileInputStream.read(b); } catch (IOException ex) { System.out.println("Error, Can't read from file"); } for (int i = 0; i < b.length; i++) { fileData += (char)b[i]; } } catch (FileNotFoundException e) { System.out.println("Error, File Not Found."); } I then send fileData as a string to the client. This works fine for txt files but when it comes to images I find that although it creates the file fine with the data in, the image won't open. I'm not sure if I'm even going about this the right way. Thanks for the help.

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  • Web Hosting: Any web host that supports files more than 50,000 in number?

    - by Devner
    Hi all, For my PHP & mySQL based application, I am trying to buy website hosting from a host who does not have a limit on the number of files I carry in my hosting account. Almost all the websites have a common limit of 50,000 files (some websites call it 50,000 nodes). The rest(to the extent of my search) are not even close. I have gone through the various websites, Googled lot of information, have spoken with the customer service of the hosting companies and they said that they have a limit of 50,000 files and that's why they call it the LIMIT. Now I have my application, which is a kind of social networking website, where people can upload various files of varying file size. So say if 50,000 users were to join the website and upload 1 file each, the limit of 50,000 will be reached very easily and my 50,001 customer will start facing file upload problems (& so will my account). So I would like to know if there's any website hosting services that do NOT levy such restrictions. In summary, I need the following options: No maximum file limit (more than 50,000 files in account). No maximum file upload limit in server setting (10MB, 12MB, 15MB, 20MB, etc.). Ability to upload files of various types (zip, flv, jg, png, etc.). Ability to stream Audio and Video (live audio & video not necessary). Access to .htaccess Access to php.ini, my.cnf or my.ini (this would be a plus) Supports SSL. Provides dedicated hosting(& IP) as well. Monthly payments without contracts are a plus. If you know of any such website hosting services, please post a reply ( a link to the same will be appreciated ). Thank you.

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  • Implementing a c/c++ style union as a column in MySQL

    - by user81338
    Friends, I have a strange need and cannot think my way through the problem. The great and mighty Google is of little help due to keyword recycling (as you'll see). Can you help? What I want to do is store data of multiple types in a single column in MySQL. This is the database equivalent to a C union (and if you search for MySQL and Union, you obviously get a whole bunch of stuff on the UNION keyword in SQL). [Contrived and simplified case follows] So, let us say that we have people - who have names - and STORMTROOPERS - who have TK numbers. You cannot have BOTH a NAME and a TK number. You're either BOB SMITH -or- TK409. In C I could express this as a union, like so: union { char * name; int tkNo; } EmperialPersonnelRecord; This makes it so that I am either storing a pointer to a char array or an ID in the type EmperialPersonnelRecord, but not both. I am looking for a MySQL equivalent on a column. My column would store either an int, double, or varchar(255) (or whatever combination). But would only take up the space of the largest element. Is this possible? (of course anything is possible given enough time, money and will - I mean is it possible if I am poor, lazy and on a deadline... aka "out of the box")

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  • How to easily map c++ enums to strings

    - by Roddy
    I have a bunch of enum types in some library header files that I'm using, and I want to have a way of converting enum values to user strings - and vice-versa. RTTI won't do it for me, because the 'user strings' need to be a bit more readable than the enumerations. A brute force solution would be a bunch of functions like this, but I feel that's a bit too C-like. enum MyEnum {VAL1, VAL2,VAL3}; String getStringFromEnum(MyEnum e) { switch e { case VAL1: return "Value 1"; case VAL2: return "Value 2"; case VAL1: return "Value 3"; default: throw Exception("Bad MyEnum"); } } I have a gut feeling that there's an elegant solution using templates, but I can't quite get my head round it yet. UPDATE: Thanks for suggestions - I should have made clear that the enums are defined in a third-party library header, so I don't want to have to change the definition of them. My gut feeling now is to avoid templates and do something like this: char * MyGetValue(int v, char *tmp); // implementation is trivial #define ENUM_MAP(type, strings) char * getStringValue(const type &T) \ { \ return MyGetValue((int)T, strings); \ } ; enum eee {AA,BB,CC}; - exists in library header file ; enum fff {DD,GG,HH}; ENUM_MAP(eee,"AA|BB|CC") ENUM_MAP(fff,"DD|GG|HH") // To use... eee e; fff f; std::cout<< getStringValue(e); std::cout<< getStringValue(f);

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  • std::conditional compile-time branch evaluation

    - by cmannett85
    Compiling this: template < class T, class Y, class ...Args > struct isSame { static constexpr bool value = std::conditional< sizeof...( Args ), typename std::conditional< std::is_same< T, Y >::value, isSame< Y, Args... >, // Error! std::false_type >::type, std::is_same< T, Y > >::type::value; }; int main() { qDebug() << isSame< double, int >::value; return EXIT_SUCCESS; } Gives me this compiler error: error: wrong number of template arguments (1, should be 2 or more) The issue is that isSame< double, int > has an empty Args parameter pack, so isSame< Y, Args... > effectively becomes isSame< Y > which does not match the signature. But my question is: Why is that branch being evaluated at all? sizeof...( Args ) is false, so the inner std:conditional should not be evaluated. This isn't a runtime piece of code, the compiler knows that sizeof..( Args ) will never be true with the given template types. If you're curious, it's supposed to be a variadic version of std::is_same, not that it works...

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  • Initialize Static Array of Structs in C

    - by russell_h
    I implementing a card game in C. There are lots of types of cards and each has a bunch of information, including some actions that will need to be individually scripted associated with it. Given a struct like this (and I'm not certain I have the syntax right for the function pointer) struct CARD { int value; int cost; // This is a pointer to a function that carries out actions unique // to this card int (*do_actions) (struct GAME_STATE *state, int choice1, int choice2); }; I would like to initialize a static array of these, one for each card. I'm guessing this would look something like this int do_card0(struct GAME_STATE *state, int choice1, int choice2) { // Operate on state here } int do_card1(struct GAME_STATE *state, int choice1, int choice2) { // Operate on state here } extern static struct cardDefinitions[] = { {0, 1, do_card0}, {1, 3, do_card1} }; Will this work, and am I going about this the right way at all? I'm trying to avoid huge numbers of switch statements. Do I need to define the 'do_cardN' functions ahead of time, or is there some way to define them inline in the initialization of the struct (something like a lambda function in python)? I'll need read-only access to cardDefinitions from a different file - is 'extern static' correct for that? I know this is a lot of questions rolled into one but I'm really a bit vague about how to go about this. Thanks.

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  • error: invalid type argument of '->' (have 'struct node')

    - by Roshan S.A
    Why cant i access the pointer "Cells" like an array ? i have allocated the appropriate memory why wont it act like an array here? it works like an array for a pointer of basic data types. #include<stdio.h> #include<stdlib.h> #include<ctype.h> #define MAX 10 struct node { int e; struct node *next; }; typedef struct node *List; typedef struct node *Position; struct Hashtable { int Tablesize; List Cells; }; typedef struct Hashtable *HashT; HashT Initialize(int SIZE,HashT H) { int i; H=(HashT)malloc(sizeof(struct Hashtable)); if(H!=NULL) { H->Tablesize=SIZE; printf("\n\t%d",H->Tablesize); H->Cells=(List)malloc(sizeof(struct node)* H->Tablesize); should it not act like an array from here on? if(H->Cells!=NULL) { for(i=0;i<H->Tablesize;i++) the following lines are the ones that throw the error { H->Cells[i]->next=NULL; H->Cells[i]->e=i; printf("\n %d",H->Cells[i]->e); } } } else printf("\nError!Out of Space"); } int main() { HashT H; H=Initialize(10,H); return 0; } The error I get is as in the title-error: invalid type argument of '->' (have 'struct node').

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  • Remove this URL string when login fails and simply show div error

    - by Anagio
    My developer built our registration page to display a div when logins failed based on a string in the URL. When logins fail this is added to the URL /login?msg=invalid The PHP in my login.phtml which displays the error messages based on the msg= parameter is <?php $msg = ""; $msg = $_GET['msg']; if($msg==""){ $showMsg = ""; } elseif($msg=="invalid"){ $showMsg = ' <div class="alert alert-error"> <a class="close" data-dismiss="alert">×</a> <strong>Error!</strong> Login or password is incorrect! </div>'; } elseif($msg=="disabled"){ $showMsg = "Your account has been disabled."; } elseif($msg==2){ $showMsg = "Your account is not activated. Please check your email."; } ?> In the controller the redirect to that URL is else //email id does not exist in our database { //redirecting back with invalid email(invalid) msg=invalid. $this->_redirect($url."?msg=invalid"); } I know there are a few other validation types for disabled accounts etc. I'm in the process of redesigning the entire interface and would like to get rid of this kind of validation so that the div tags display when logins fail but not show the URL strings. If it matters the new div I want to display is <div class="alert alert-error alert-login"> Email or password incorrect </div> I'd like to replace the php my self in my login.phtml and controller but not a good programmer. What can I replace $this->_redirect($url."?msg=invalid"); with so that no strings are added to the URL and display the appropriate div tags? Thanks

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  • Java: Generics, Class.isaAssignableFrom, and type casting

    - by bguiz
    This method that uses method-level generics, that parses the values from a custom POJO, JXlistOfKeyValuePairs (which is exactly that). The only thing is that both the keys and values in JXlistOfKeyValuePairs are Strings. This method wants to taken in, in addition to the JXlistOfKeyValuePairs instance, a Class<T> that defines which data type to convert the values to (assume that only Boolean, Integer and Float are possible). It then outputs a HashMap with the specified type for the values in its entries. This is the code that I have got, and it is obviously broken. private <T extends Object> Map<String, T> fromListOfKeyValuePairs(JXlistOfKeyValuePairs jxval, Class<T> clasz) { Map<String, T> val = new HashMap<String, T>(); List<Entry> jxents = jxval.getEntry(); T value; String str; for (Entry jxent : jxents) { str = jxent.getValue(); value = null; if (clasz.isAssignableFrom(Boolean.class)) { value = (T)(Boolean.parseBoolean(str)); } else if (clasz.isAssignableFrom(Integer.class)) { value = (T)(Integer.parseInt(str)); } else if (clasz.isAssignableFrom(Float.class)) { value = (T)(Float.parseFloat(str)); } else { logger.warn("Unsupporteded value type encountered in key-value pairs, continuing anyway: " + clasz.getName()); } val.put(jxent.getKey(), value); } return val; } This is the bit that I want to solve: if (clasz.isAssignableFrom(Boolean.class)) { value = (T)(Boolean.parseBoolean(str)); } else if (clasz.isAssignableFrom(Integer.class)) { value = (T)(Integer.parseInt(str)); } I get: Inconvertible types required: T found: Boolean Also, if possible, I would like to be able to do this with more elegant code, avoiding Class#isAssignableFrom. Any suggestions? Sample method invocation: Map<String, Boolean> foo = fromListOfKeyValuePairs(bar, Boolean.class);

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  • Most efficient method of detecting/monitoring DOM changes?

    - by Graza
    I need an efficient mechanism for detecting changes to the DOM. Preferably cross-browser, but if there's any efficient means which are not cross browser, I can implement these with a fail-safe cross browser method. In particular, I need to detect changes that would affect the text on a page, so any new, removed or modified elements, or changes to inner text (innerHTML) would be required. I don't have control over the changes being made (they could be due to 3rd party javascript includes, etc), so it can't be approached from this angle - I need to "monitor" for changes somehow. Currently I've implemented a "quick'n'dirty" method which checks body.innerHTML.length at intervals. This won't of course detect changes which result in the same length being returned, but in this case is "good enough" - the chances of this happening are extremely slim, and in this project, failing to detect a change won't result in lost data. The problem with body.innerHTML.length is that it's expensive. It can take between 1 and 5 milliseconds on a fast browser, and this can bog things down a lot - I'm also dealing with a large-ish number of iframes and it all adds up. I'm pretty sure the expensiveness of doing this is because the innerHTML text is not stored statically by browsers, and needs to be calculated from the DOM every time it is read. The types of answers I am looking for are anything from the "precise" (for example event) to the "good enough" - perhaps something as "quick'n'dirty" as the innerHTML.length method, but that executes faster.

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