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Alex Rivera
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I've been developing a GUI library for Windows (as a personal side project, no aspirations of usefulness). For my main window class, I've set up a hierarchy of option classes (using the Named Parameter Idiom ), because some options are shared and others are specific to particular types of windows (like dialogs). The way the Named Parameter Idiom works, the functions of the parameter class have to return the object they're called on. The problem is that, in the hierarchy, each one has to be a different class -- the createWindowOpts class for standard windows, the createDialogOpts class for dialogs, and the like. I've dealt with that by making all the option classes templates. Here's an example: template <class T> class _sharedWindowOpts: public detail::_baseCreateWindowOpts { public: /////////////////////////////////////////////////////////////// // No required parameters in this case. _sharedWindowOpts() { }; typedef T optType; // Commonly used options optType& at(int x, int y) { mX=x; mY=y; return static_cast<optType&>(*this); }; // Where to put the upper-left corner of the window; if not specified, the system sets it to a default position optType& at(int x, int y, int width, int height) { mX=x; mY=y; mWidth=width; mHeight=height; return static_cast<optType&>(*this); }; // Sets the position and size of the window in a single call optType& background(HBRUSH b) { mBackground=b; return static_cast<optType&>(*this); }; // Sets the default background to this brush optType& background(INT_PTR b) { mBackground=HBRUSH(b+1); return static_cast<optType&>(*this); }; // Sets the default background to one of the COLOR_* colors; defaults to COLOR_WINDOW optType& cursor(HCURSOR c) { mCursor=c; return static_cas
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