Windows component object model programming

Windows lets you share code at the binary level using DLLs. After all, that's how Windows apps function - reusing kernel But since the DLLs are written to a C interface, they can only be used by C or languages that understand the C calling convention. This puts the burden of sharing on the programming language implementer, instead of on the DLL itself. But these are even more restrictive - you can only use them from an MFC app. The standard also specifies exactly how COM objects must be organized in memory.

Once that's done, the modules can be accessed easily from any programming language. A binary standard puts the burden of compatibility on the compiler that produces the binaries, which makes it much easier for the folks who come along later and need to use those binaries.

But remember, the language that the module is written in is irrelevant, because the resulting binary is usable by all languages. Incidentally, COM is not Winspecific. It could, in theory, be ported to Unix or any other OS. Let's go from the bottom up. An interface is simply a group of functions. Those functions are called methods. Interface names start with I , for example IShellLink.

Interfaces may inherit from other interfaces. Multiple inheritance is not allowed with interfaces. A coclass short for c omponent o bject class is contained in a DLL or EXE, and contains the code behind one or more interfaces.

The coclass is said to implement those interfaces. A COM object is an instance of a coclass in memory. Registration is the process of creating registry entries that tell Windows where a COM server is located. Unregistration is the opposite - removing those registry entries. A GUID rhymes with "fluid", stands for g lobally u nique id entifier is a bit number.

For more information, see vcpkg. Microsoft Foundation Classes MFC : An object-oriented framework for creating traditional Windows programs—especially enterprise applications—that have rich user interfaces that feature buttons, list boxes, tree views, and other controls. Concurrency Runtime: A library that simplifies the work of parallel and asynchronous programming for multicore and many-core devices. For more information, see Concurrency Runtime.

Many Windows programming scenarios also require the Windows SDK, which includes the header files that enable access to the Windows operating system components.

For more information, and a download link, see Windows SDK. Visual Studio includes a powerful debugger for native code, static analysis tools, graphics debugging tools, a full-featured code editor, support for unit tests, and many other tools and utilities. Skip to main content. This browser is no longer supported. Download Microsoft Edge More info. Contents Exit focus mode. Is this page helpful?

Please rate your experience Yes No. They can be written in different languages, and they may be structurally quite dissimilar, which is why COM is referred to as a binary standard ; a standard that applies after a program has been translated to binary machine code. The only language requirement for COM is that code is generated in a language that can create structures of pointers and, either explicitly or implicitly, call functions through pointers.

In general, a software object is made up of a set of data and the functions that manipulate the data. A COM object is one in which access to an object's data is achieved exclusively through one or more sets of related functions. These function sets are called interfaces , and the functions of an interface are called methods. This feature enables the system to abort a transaction automatically if an exception is triggered or to commit if not. Skip to main content.

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