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  • How do I work around the GCC "error: cast from ‘SourceLocation*’ to ‘int’ loses precision" error when compiling cmockery.c?

    - by Daryl Spitzer
    I need to add unit tests using Cmockery to an existing build environment that uses as hand-crafted Makefile. So I need to figure out how to build cmockery.c (without automake). When I run: g++ -DHAVE_CONFIG_H -DPIC -I ../cmockery-0.1.2 -I /usr/include/malloc -c ../cmockery-0.1.2/cmockery.c -o obj/cmockery.o I get a long list of errors like this: ../cmockery-0.1.2/cmockery.c: In function ‘void initialize_source_location(SourceLocation*)’: ../cmockery-0.1.2/cmockery.c:248: error: cast from ‘SourceLocation*’ to ‘int’ loses precision Here are lines 247:248 of cmockery.c: static void initialize_source_location(SourceLocation * const location) { assert_true(location); assert_true is defined on line 154 of cmockery.h: #define assert_true(c) _assert_true((int)(c), #c, __FILE__, __LINE__) So the problem (as the error states) is GCC doesn't like the cast from ‘SourceLocation*’ to ‘int’. I can build Cmockery using ./configure and make (on Linux, and on Mac OS X if I export CFLAGS=-I/usr/include/malloc first), without any errors. I've tried looking at the command-line that compiles cmockery.c when I run make (after ./configure): gcc -DHAVE_CONFIG_H -I. -I. -I./src -I./src -Isrc/google -I/usr/include/malloc -MT libcmockery_la-cmockery.lo -MD -MP -MF .deps/libcmockery_la-cmockery.Tpo -c src/cmockery.c -fno-common -DPIC -o .libs/libcmockery_la-cmockery.o ...but I don't see any options that might work around this error. In "error: cast from 'void*' to 'int' loses precision", I see I could change (int) in cmockery.h to (intptr_t). And I've confirmed that works. But since I can build Cmockery with ./configure and make, there must be a way to get it to build without modifying the source.

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  • How do I cast a void pointer to a struct in C?

    - by Rowhawn
    In a project I'm writing code for, I have a void pointer, "implementation", which is a member of a "Hash_map" struct, and points to an "Array_hash_map" struct. The concepts behind this project are not very realistic, but bear with me. The specifications of the project ask that I cast the void pointer "implementation" to an "Array_hash_map" before I can use it in any functions. My question, specifically is, what do I do in the functions to cast the void pointers to the desired struct? Is there one statement at the top of each function that casts them or do I make the cast every time I use "implementation"? Here are the typedefs the structs of a Hash_map and Array_hash_map as well as a couple functions making use of them. typedef struct { Key_compare_fn key_compare_fn; Key_delete_fn key_delete_fn; Data_compare_fn data_compare_fn; Data_delete_fn data_delete_fn; void *implementation; } Hash_map; typedef struct Array_hash_map{ struct Unit *array; int size; int capacity; } Array_hash_map; typedef struct Unit{ Key key; Data data; } Unit; functions: /* Sets the value parameter to the value associated with the key parameter in the Hash_map. */ int get(Hash_map *map, Key key, Data *value){ int i; if (map == NULL || value == NULL) return 0; for (i = 0; i < map->implementation->size; i++){ if (map->key_compare_fn(map->implementation->array[i].key, key) == 0){ *value = map->implementation->array[i].data; return 1; } } return 0; } /* Returns the number of values that can be stored in the Hash_map, since it is represented by an array. */ int current_capacity(Hash_map map){ return map.implementation->capacity; }

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  • How do I cast from int to generic type Integer?

    - by Rob Kent
    I'm relatively new to Java and am used to generics in C# so have struggled a bit with this code. Basically I want a generic method for getting a stored Android preference by key and this code, albeit ugly, works for a Boolean but not an Integer, when it blows up with a ClassCastException. Can anyone tell me why this is wrong and maybe help me improve the whole routine (using wildcards?)? public static <T> T getPreference(Class<T> argType, String prefKey, T defaultValue, SharedPreferences sharedPreferences) { ... try { if (argType == Boolean.class) { Boolean def = (Boolean) defaultValue; return argType.cast(sharedPreferences.getBoolean(prefKey, def)); } else if (argType == Integer.class) { Integer def = (Integer) defaultValue; return argType.cast(sharedPreferences.getInt(prefKey, def)); } else { AppGlobal.logWarning("getPreference: Unknown type '%s' for preference '%s'. Returning default value.", argType.getName(), prefKey); return defaultValue; } } catch (ClassCastException e) { AppGlobal.logError("Cast exception when reading pref %s. Using default value.", prefKey); return defaultValue; } } I've tried various ways - using the native int, casting to an Integer, but nothing works.

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  • Could this C cast to avoid a signed/unsigned comparison make any sense?

    - by sharptooth
    I'm reviewing a C++ project and see effectively the following: std::vector<SomeType> objects; //then later int size = (int)objects.size(); for( int i = 0; i < size; ++i ) { process( objects[i] ); } Here's what I see. std::vector::size() returns size_t that can be of some size not related to the size of int. Even if sizeof(int) == sizeof(size_t) int is signed and can't hold all possible values of size_t. So the code above could only process the lower part of a very long vector and contains a bug. That said I'm curious of why the author might have written this? My only guess is that first he omitted the (int) cast and the compiler emitted something like Visual C++ C4018 warning: warning C4018: '<' : signed/unsigned mismatch so the author though that the best way to avoid the compiler warning would be to simply cast the size_t to int thus making the compiler shut up. Is there any other possible sane reason for that C cast?

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  • How to fix “Unable to cast COM object of type ‘Microsoft.SharePoint.Library.SPRequestInternalClass’ to interface type ‘Microsoft.SharePoint.Library.ISPRequest” using PowerGUI

    - by ybbest
    I got the error today when debugging some of my PowerShell Script in PowerGUI. The script works perfectly fine in PowerShell console. Then I had spent a couple of hours scratching my head, trying to figure out why. It turns out that the PowerShell Variables Panel causes the problem. Not quite sure why, but collapse the panel fix the problem. Problem: It throws the following exception when debugging my PowerShell Script. Analysis: It turns out that the PowerShell Variables Panel causes the problem. I assume it calls some function to grab value of some of variables which cause the problems. Solution: Collapse or Close the variables panel fix the problem

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  • How can I retrieve statistics from my ghost cast server?

    - by Foxtrot
    I have a GhostCast server running for deploying images. I would like to have each ghost cast session to write to a file ( can be multiple text files or append to one file already there ) statistics. I know this is possible based on the options GhostCast software provides for writing to a log file, but I would like this automated for every image being backed up and restored. I don't want to have my employees click write to a new file every time. Is this possible?

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  • Doctrine Mssql uniqueidentifier isn't cast as char or nvarchar when retrieved from the database.

    - by Tres
    When I retrieve a record from the database which has a column of type "uniqueidentifier", Doctrine fills it with "null" rather than the unique id from the database. Some research and testing has brought this down to a PDO/dblib driver issue. When directly querying via PDO, null is returned in place of the unique id. For reference, http://trac.doctrine-project.org/ticket/1096, has a bit on this, however, it was updated 11 months ago with no comment for resolution. A way around this, as mentioned at http://bugs.php.net/bug.php?id=24752&edit=1, is to cast the column as a char. However, it doesn't seem Doctrine exposes the native field type outside of generating models which makes it a bit hard to detect uniqueidentifier types and cast them internally when building the sql query. Has anyone found a workaround for this?

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  • Why doesn't an octal literal as a string cast to a number?

    - by Andy E
    In JavaScript, why does an octal number string cast as a decimal number? I can cast a hex literal string using Number() or +, why not an octal? For instance: 1000 === +"1000" // -> true 0xFF === +"0xFF" // -> true 0100 === +"0100" // -> false - +"0100" gives 100, not 64 I know I can parse with parseInt("0100" [, 8]), but I'd like to know why casting doesn't work like it does with hex and dec numbers. Also, does anyone know why octal literals are dropped from ECMAScript 5th Edition in strict mode?

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  • Can you cast an object to one that implements an interface? (JAVA)

    - by DDP
    Can you cast an object to one that implements an interface? Right now, I'm building a GUI, and I don't want to rewrite the Confirm/Cancel code (A confirmation pop-up) over and over again. So, what I'm trying to do is write a class that gets passed the class it's used in and tells the class whether or not the user pressed Confirm or Cancel. The class always implements a certain interface. Code: class ConfirmFrame extends JFrame implements ActionListener { JButton confirm = new JButton("Confirm"); JButton cancel = new JButton("Cancel"); Object o; public ConfirmFrame(Object o) { // Irrelevant code here add(confirm); add(cancel); this.o = (/*What goes here?*/)o; } public void actionPerformed( ActionEvent evt) { o.actionPerformed(evt); } } I realize that I'm probably over-complicating things, but now that I've run across this, I really want to know if you can cast an object to another object that implements a certain interface.

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  • How does one avoid "Value restriction" errors with F#'s Seq.cast?

    - by gatoatigrado
    I see that Seq has a cast function from IEnumerable to Seq, but how do I get it to work? open System.Text.RegularExpressions;; let v = Regex.Match("abcd", "(ab)");; Seq.cast (v.Captures);; This produces, error FS0030: Value restriction. The value 'it' has been inferred to have generic type val it : seq<'_a Either define 'it' as a simple data term, make it a function with explicit arguments or, if you do not intend for it to be generic, add a type annotation.

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  • Safe to cast pointer to a forward-declared class to its true base class in C++?

    - by Matt DiMeo
    In one header file I have: #include "BaseClass.h" // a forward declaration of DerivedClass, which extends class BaseClass. class DerivedClass ; class Foo { DerivedClass *derived ; void someMethod() { // this is the cast I'm worried about. ((BaseClass*)derived)->baseClassMethod() ; } }; Now, DerivedClass is (in its own header file) derived from BaseClass, but the compiler doesn't know that at the time it's reading the definition above for class Foo. However, Foo refers to DerivedClass pointers and DerivedClass refers to Foo pointers, so they can't both know each other's declaration. First question is whether it's safe (according to C++ spec, not in any given compiler) to cast a derived class pointer to its base class pointer type in the absence of a full definition of the derived class. Second question is whether there's a better approach. I'm aware I could move someMethod()'s body out of the class definition, but in this case it's important that it be inlined (part of an actual, measured hotspot - I'm not guessing).

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  • In Java how instance of and type cast(i.e (ClassName)) works on proxy object ?

    - by learner
    Java generates a proxy class for a given interface and provides the instance of the proxy class. But when we type cast the proxy object to our specific Object, how java handles this internally? Is this treated as special scenario? For example I have class 'OriginalClass' and it implements 'OriginalInterface', when I create proxy object by passing 'OriginalInterface' interface java created proxy class 'ProxyClass' using methods in the provided interface and provides object of this class(i.e ProxyClass). If my understanding is correct then can you please answer following queries 1) When I type cast object of ProxyClass to my class OriginalClass this works, but how java is allowing this? Same in case of instace of? 2) As my knowledge java creates a proxy class only with the methods, but what happen when I try to access attributes on this object? 3) Only interface methods are getting implemented in Proxy, but what happens when I try to access a method which not in interface and only mentioned in the class? Thanks, Student

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  • Why do I have to explicitly cast sometimes for varargs?

    - by Daniel Lew
    I've got a Class that uses reflection a lot, so I wrote a method to help out: private <T> T callMethod(String methodName, Class[] parameterTypes, Object[] args) { try { Class c = mVar.getClass(); Method m = c.getMethod(methodName, (Class[]) parameterTypes); return (T) m.invoke(mVar, args); } // Insert exception catching here [...] } This worked well for any method that had parameters, however I had to explicitly cast parameterTypes to Class[] in order for this to work for methods with no parameters (e.g., callMethod('funName', null, null);). I've been trying to figure out why this is the case. It seems to me that if parameterTypes, when null, had no concept of what type it is (Class[]), then I'd need to cast it for getMethod(). But if that's the case, why is getMethod() able to tell the difference between null, and (Class[]) null when the method is invoked?

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  • how to cast an array of char into a single integer number?

    - by SepiDev
    Hi guys, i'm trying to read contents of PNG file. As you may know, all data is written in a 4-byte manner in png files, both text and numbers. so if we have number 35234 it is save in this way: [1000][1001][1010][0010]. but sometimes numbers are shorter, so the first bytes are zero, and when I read the array and cast it from char* to integer I get wrong number. for example [0000] [0000] [0001] [1011] sometimes numbers are misinterpreted as negative numbers and simetimes as zero! let me give you an intuitive example: char s_num[4] = {120, 80, 40, 1}; int t_num = 0; t_num = int(s_num); => 3215279148 ?????? the result should be 241 but the output is 3215279148? I wish I could explain my problem well! how can i cast such arrays into a single integer value?

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  • how to open multiple projects into the CAST IRON integration tool?

    - by MIshal Shah
    Hi, I am learning the cast iron tool (http://www.castiron.com/) which is widely used now a days for integration purpose,but i can only open 1 project and if i want to open the other project at the same time than i have to close the 1st project and after that able to open the 2nd project. So many times i have to open 2 projects at the same time but i dont know in which way i can open the projects ? can any body give me any urgent solution for the same to open the multiple projects at the same time and to switch between them ? Thanks, Mishal Shah

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  • MS SQL server and Trees

    - by Julian
    Im looking for some way of extrating data form a tree table as defined below. Table Tree Defined as :- TreeID uniqueidentifier TreeParent uniqueidentifier TreeCode varchar(50) TreeDesc varchar(100) Data some (23k rows), Parent Refs back into ID in table The following SQL renders the whole tree (takes arround 2 mins 30) I need to do the following. 1) Render each Tree Node with its LVL 1 parent 2) Render all nodes that have a Description that matches a TreeDesc like 'SomeText%' 3) Render all parent nodes that are for a single tree id. Items 2 and 3 take 2mins30 so this needs to be a lot faster! Item 1, just cant work out how to do it with out killing SQL or taking forever any sugestions would be helpfull Thanks Julian WITH TreeCTE(TreeCode, TreeDesc, depth, TreeParent, TreeID) AS ( -- anchor member SELECT cast('' as varchar(50)) as TreeCode , cast('Trees' as varchar(100)) as TreeDesc, cast('0' as Integer) as depth, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier) as TreeParent, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier) as TreeID UNION ALL -- recursive member SELECT s.TreeCode, s.TreeDesc, cte.depth+1, isnull(s.TreeParent, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier)), isnull(s.TreeID, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier)) FROM pdTrees AS S JOIN TreeCTE AS cte ON isnull(s.TreeParent, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier)) = isnull( cte.TreeID , cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier)) ) -- outer query SELECT s.TreeID, s.TreeCode, s.TreeDesc, s.depth, s.TreeParent FROM TreeCTE s

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  • Need to get 3 record for database on current date using sqlite

    - by Umaid
    SELECT rowid, Day, Advice from MainCategory where ((Day = ((cast(strftime('%d',date('now','-1 day')) as Integer)))) and (Month = (strftime('%m',date('now'))))) and ((Day = ((cast(strftime('%d',date('now')) as Integer)))) and (Month = (strftime('%m',date('now'))))) , ((Day = ((cast(strftime('%d',date('now','+1 day')) as Integer)))) and (Month = (strftime('%m',date('now',+1 month))))); What if i make my Month column in Integer data type then it would be. SELECT rowid, Month, Day, Advice from MainCategory where ((Day = ((cast(strftime('%d',date('now','-1 day')) as Integer)))) and (Month = (strftime('%m',date('now'))))) and ((Day = ((cast(strftime('%d',date('now')) as Integer)))) and (Month = (strftime('%m',date('now'))))) , ((Day = ((cast(strftime('%d',date('now','+1 day')) as Integer)))) and (Month = (strftime('%m',date('now',+1 month))))); Please note that I have over this scenerio when I am in middle of month but below query returns 2 records and 1 from begining from all 11 months as (feb is exclusive) then record will be 33 but i need three 3 records from the table and increment it on next button. Please write 3 querys one which return all three record on current date, next all 3 records must be incremented by 1 on every next button click finally all 3 records must be decremented by 1 on every previous button click keep last day and begining date on the month in minds else i have also achieved for middle of month. Running query but returns 33 records instead of 3. SELECT rowid,Month, Day, Advice from MainCategory where Day in ((cast(strftime('%d',date('now','-1 day')) as Integer)),(cast(strftime('%d',date('now')) as Integer)),(cast(strftime('%d',date('now','+1 day')) as Integer)));

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  • The Ins and Outs of Effective Smart Grid Data Management

    - by caroline.yu
    Oracle Utilities and Accenture recently sponsored a one-hour Web cast entitled, "The Ins and Outs of Effective Smart Grid Data Management." Oracle and Accenture created this Web cast to help utilities better understand the types of data collected over smart grid networks and the issues associated with mapping out a coherent information management strategy. The Web cast also addressed important points that utilities must consider with the imminent flood of data that both present and next-generation smart grid components will generate. The three speakers, including Oracle Utilities' Brad Williams, focused on the key factors associated with taking the millions of data points captured in real time and implementing the strategies, frameworks and technologies that enable utilities to process, store, analyze, visualize, integrate, transport and transform data into the information required to deliver targeted business benefits. The Web cast replay is available here. The Web cast slides are available here.

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  • The Excel Column Name assigment problem

    - by Peter Larsson
    Here is a generic algorithm to get the Excel column name according to it's position. By changing the @Base parameter, you can do this for any sequence according to same style as Excel. DECLARE @Value INT = 8839,         @Base TINYINT = 26   ;WITH cteSequence(Value, Delta, Quote, Base, Chr) AS (     SELECT  CAST(@Value AS INT) AS Value,             CAST(1 AS INT) AS Delta,             CAST(@Base AS INT) AS Quote,             CAST(@Base AS INT) AS Base,             CHAR(65 +(@Value - 1) % @Base) AS Chr       UNION ALL       SELECT  Value AS Value,             Quote AS Delta,             26 * Quote AS Quote,             Base AS Base,             CHAR(65 +((Value - Delta)/ Quote - 1) % Base) AS Chr     FROM    cteSequence     WHERE   CHAR(65 +((Value - Delta)/ Quote - 1) % Base) <> '@' ) SELECT  CAST(Msg AS VARCHAR(MAX)) FROM    (             SELECT        '' + Chr             FROM        cteSequence             ORDER BY    Delta DESC             FOR XML        PATH('')         ) AS x(Msg)

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  • error : java.lang.String cannot be cast to coldfusion.cfc.CFCBeanProxy anyone know about this ?

    - by faheem
    Hi does anyone know about this error I get when I try to insert a foreign key value in my entry entity using cf9 Hibernate ? java.lang.ClassCastException: java.lang.String cannot be cast to coldfusion.cfc.CFCBeanProxy Root cause :org.hibernate.HibernateException: java.lang.ClassCastException: java.lang.String cannot be cast to coldfusion.cfc.CFCBeanProxy Below is the code for my entity object and then for my user object.. Is there anything wrong with this ? entry.cfc /** * Entries Object */ component output="false" persistent="true"{ property name="entry_id" fieldType="id" generator="uuid"; property name="entryBody" ormType="text"; property name="title" notnull="true" type="string"; property name="time" fieldtype="timestamp"; property name="isCompleted" ormType="boolean" dbdefault="0" default="false"; property name="userID" fieldtype="many-to-one" fkcolumn="userID" cfc="user"; Entry function init() output=false{ return this; } } user.cfc /** * Users Object */ component output="false" persistent="true"{ property name="userID" fieldType="id" generator="uuid"; property name="firstName" notnull="true" type="string"; property name="lastName" notnull="true" type="string"; property name="password" notnull="true" type="string"; property name="userType" notnull="true" type="string"; //property name="entry" fieldtype="one-to-many" type="array" fkcolumn="userID" cfc="entry"; User function init() output=false{ return this; } }

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  • Dynamic Types and DynamicObject References in C#

    - by Rick Strahl
    I've been working a bit with C# custom dynamic types for several customers recently and I've seen some confusion in understanding how dynamic types are referenced. This discussion specifically centers around types that implement IDynamicMetaObjectProvider or subclass from DynamicObject as opposed to arbitrary type casts of standard .NET types. IDynamicMetaObjectProvider types  are treated special when they are cast to the dynamic type. Assume for a second that I've created my own implementation of a custom dynamic type called DynamicFoo which is about as simple of a dynamic class that I can think of:public class DynamicFoo : DynamicObject { Dictionary<string, object> properties = new Dictionary<string, object>(); public string Bar { get; set; } public DateTime Entered { get; set; } public override bool TryGetMember(GetMemberBinder binder, out object result) { result = null; if (!properties.ContainsKey(binder.Name)) return false; result = properties[binder.Name]; return true; } public override bool TrySetMember(SetMemberBinder binder, object value) { properties[binder.Name] = value; return true; } } This class has an internal dictionary member and I'm exposing this dictionary member through a dynamic by implementing DynamicObject. This implementation exposes the properties dictionary so the dictionary keys can be referenced like properties (foo.NewProperty = "Cool!"). I override TryGetMember() and TrySetMember() which are fired at runtime every time you access a 'property' on a dynamic instance of this DynamicFoo type. Strong Typing and Dynamic Casting I now can instantiate and use DynamicFoo in a couple of different ways: Strong TypingDynamicFoo fooExplicit = new DynamicFoo(); var fooVar = new DynamicFoo(); These two commands are essentially identical and use strong typing. The compiler generates identical code for both of them. The var statement is merely a compiler directive to infer the type of fooVar at compile time and so the type of fooExplicit is DynamicFoo, just like fooExplicit. This is very static - nothing dynamic about it - and it completely ignores the IDynamicMetaObjectProvider implementation of my class above as it's never used. Using either of these I can access the native properties:DynamicFoo fooExplicit = new DynamicFoo();// static typing assignmentsfooVar.Bar = "Barred!"; fooExplicit.Entered = DateTime.Now; // echo back static values Console.WriteLine(fooVar.Bar); Console.WriteLine(fooExplicit.Entered); but I have no access whatsoever to the properties dictionary. Basically this creates a strongly typed instance of the type with access only to the strongly typed interface. You get no dynamic behavior at all. The IDynamicMetaObjectProvider features don't kick in until you cast the type to dynamic. If I try to access a non-existing property on fooExplicit I get a compilation error that tells me that the property doesn't exist. Again, it's clearly and utterly non-dynamic. Dynamicdynamic fooDynamic = new DynamicFoo(); fooDynamic on the other hand is created as a dynamic type and it's a completely different beast. I can also create a dynamic by simply casting any type to dynamic like this:DynamicFoo fooExplicit = new DynamicFoo(); dynamic fooDynamic = fooExplicit; Note that dynamic typically doesn't require an explicit cast as the compiler automatically performs the cast so there's no need to use as dynamic. Dynamic functionality works at runtime and allows for the dynamic wrapper to look up and call members dynamically. A dynamic type will look for members to access or call in two places: Using the strongly typed members of the object Using theIDynamicMetaObjectProvider Interface methods to access members So rather than statically linking and calling a method or retrieving a property, the dynamic type looks up - at runtime  - where the value actually comes from. It's essentially late-binding which allows runtime determination what action to take when a member is accessed at runtime *if* the member you are accessing does not exist on the object. Class members are checked first before IDynamicMetaObjectProvider interface methods are kick in. All of the following works with the dynamic type:dynamic fooDynamic = new DynamicFoo(); // dynamic typing assignments fooDynamic.NewProperty = "Something new!"; fooDynamic.LastAccess = DateTime.Now; // dynamic assigning static properties fooDynamic.Bar = "dynamic barred"; fooDynamic.Entered = DateTime.Now; // echo back dynamic values Console.WriteLine(fooDynamic.NewProperty); Console.WriteLine(fooDynamic.LastAccess); Console.WriteLine(fooDynamic.Bar); Console.WriteLine(fooDynamic.Entered); The dynamic type can access the native class properties (Bar and Entered) and create and read new ones (NewProperty,LastAccess) all using a single type instance which is pretty cool. As you can see it's pretty easy to create an extensible type this way that can dynamically add members at runtime dynamically. The Alter Ego of IDynamicObject The key point here is that all three statements - explicit, var and dynamic - declare a new DynamicFoo(), but the dynamic declaration results in completely different behavior than the first two simply because the type has been cast to dynamic. Dynamic binding means that the type loses its typical strong typing, compile time features. You can see this easily in the Visual Studio code editor. As soon as you assign a value to a dynamic you lose Intellisense and you see which means there's no Intellisense and no compiler type checking on any members you apply to this instance. If you're new to the dynamic type it might seem really confusing that a single type can behave differently depending on how it is cast, but that's exactly what happens when you use a type that implements IDynamicMetaObjectProvider. Declare the type as its strong type name and you only get to access the native instance members of the type. Declare or cast it to dynamic and you get dynamic behavior which accesses native members plus it uses IDynamicMetaObjectProvider implementation to handle any missing member definitions by running custom code. You can easily cast objects back and forth between dynamic and the original type:dynamic fooDynamic = new DynamicFoo(); fooDynamic.NewProperty = "New Property Value"; DynamicFoo foo = fooDynamic; foo.Bar = "Barred"; Here the code starts out with a dynamic cast and a dynamic assignment. The code then casts back the value to the DynamicFoo. Notice that when casting from dynamic to DynamicFoo and back we typically do not have to specify the cast explicitly - the compiler can induce the type so I don't need to specify as dynamic or as DynamicFoo. Moral of the Story This easy interchange between dynamic and the underlying type is actually super useful, because it allows you to create extensible objects that can expose non-member data stores and expose them as an object interface. You can create an object that hosts a number of strongly typed properties and then cast the object to dynamic and add additional dynamic properties to the same type at runtime. You can easily switch back and forth between the strongly typed instance to access the well-known strongly typed properties and to dynamic for the dynamic properties added at runtime. Keep in mind that dynamic object access has quite a bit of overhead and is definitely slower than strongly typed binding, so if you're accessing the strongly typed parts of your objects you definitely want to use a strongly typed reference. Reserve dynamic for the dynamic members to optimize your code. The real beauty of dynamic is that with very little effort you can build expandable objects or objects that expose different data stores to an object interface. I'll have more on this in my next post when I create a customized and extensible Expando object based on DynamicObject.© Rick Strahl, West Wind Technologies, 2005-2012Posted in CSharp  .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Compiler issues on VC++ 2008 Express, Seemingly correct code throws errors.

    - by Anthony Clever
    Hi there, I've been trying to get back into coding for a while, so I figured I'd start with some simple SDL, now, without the file i/o, this compiles fine, but when I throw in the stdio code, it starts throwing errors. This I'm not sure about, I don't see any problem with the code itself, however, like I said, I might as well be a newbie, and figured I'd come here to get someone with a little more experience with this type of thing to look at it. I guess my question boils down to: "Why doesn't this compile under Microsoft's Visual C++ 2008 Express?" I've attached the error log at the bottom of the code snippet. Thanks in advance for any help. #include "SDL/SDL.h" #include "stdio.h" int main(int argc, char *argv[]) { FILE *stderr; FILE *stdout; stderr = fopen("stderr", "wb"); stdout = fopen("stdout", "wb"); SDL_Init(SDL_INIT_EVERYTHING); fprintf(stdout, "SDL INITIALIZED SUCCESSFULLY\n"); SDL_Quit(); fprintf(stderr, "SDL QUIT.\n"); fclose(stderr); fclose(stdout); return 0; } /* 1>------ Build started: Project: opengl_crap, Configuration: Debug Win32 ------ 1>Compiling... 1>main.cpp 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(6) : error C2090: function returns array 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(6) : error C2528: '__iob_func' : pointer to reference is illegal 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(6) : error C2556: 'FILE ***__iob_func(void)' : overloaded function differs only by return type from 'FILE *__iob_func(void)' 1> c:\program files\microsoft visual studio 9.0\vc\include\stdio.h(132) : see declaration of '__iob_func' 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(7) : error C2090: function returns array 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(7) : error C2528: '__iob_func' : pointer to reference is illegal 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(9) : error C2440: '=' : cannot convert from 'FILE *' to 'FILE ***' 1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(10) : error C2440: '=' : cannot convert from 'FILE *' to 'FILE ***' 1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(13) : error C2664: 'fprintf' : cannot convert parameter 1 from 'FILE ***' to 'FILE *' 1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(15) : error C2664: 'fprintf' : cannot convert parameter 1 from 'FILE ***' to 'FILE *' 1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(17) : error C2664: 'fclose' : cannot convert parameter 1 from 'FILE ***' to 'FILE *' 1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(18) : error C2664: 'fclose' : cannot convert parameter 1 from 'FILE ***' to 'FILE *' 1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast 1>Build log was saved at "file://c:\Documents and Settings\Owner\My Documents\Visual Studio 2008\Projects\opengl_crap\opengl_crap\Debug\BuildLog.htm" 1>opengl_crap - 11 error(s), 0 warning(s) ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== */

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