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58 lines
2.1 KiB
C
58 lines
2.1 KiB
C
#pragma once
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/*
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http://msdn.microsoft.com/en-us/magazine/cc301398.aspx
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These days abstract classes are
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not just common, they're ubiquitous. Think: where in Windows® do
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abstract classes appear over and over again? That's right, in COM!
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A COM interface is an abstract class with only pure virtual functions.
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As everything in Windows migrates to COM land, Windows-based programs
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have COM interfaces up the wazoo. A typical COM class might implement
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a dozen or more interfaces, each with several functions.
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Even outside COM, the notion of an interface is quite powerful
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and useful, as in the Java language. Each interface implementation might
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use several layers of classes, none intended to be used by themselves,
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but only as base classes for yet more classes. ATL provides many such
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classes using templates, another source of class proliferation. All of
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this adds up to lots of initialization code and useless vtables with
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NULL entries. The total bloat can become significant, especially when
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you're developing small objects that must load over a slow medium like
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the Internet.
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So __declspec(novtable) was invented to solve the problem. It's a
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Microsoft-specific optimization hint that tells the compiler: this class
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is never used by itself, but only as a base class for other classes, so
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don't bother with all that vtable stuff, thank you.
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*/
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#ifdef _WIN32
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// Decoration to indicate a class is to be treated as an "Interface"
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// The class should contain pure virtual functions and maybe a little
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// trivial code. Otherwise, use RBXBaseClass.
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// !!! You can't define a virtual destructor for a class of this type
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#define RBXInterface __declspec(novtable)
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// Decoration to indicate a class should not be instantiated directly
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// !!! You can't define a virtual destructor for a class of this type
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#define RBXBaseClass __declspec(novtable)
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/****
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Note:
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C++ doesn't have a strict "Interface" type. RBXInterface should be used
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for classes that declare only pure virtual functions and maybe a constructor
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and/or a field. Classes that define non-trivial code should use RBXBaseClass instead.
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***/
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#else
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#define RBXInterface
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#define RBXBaseClass
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#endif
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