C++模板会使代码膨胀吗 - c++编程基础

04d900c HYTeris!ATL::CWindowImplRoot >::`RTTI Base Class Descriptor at (0,-1,0,64)' =
可以看到 CWindowImplRoot只和窗口基类(CWindow)相关，所以相关的符号就更少了。

最后我们再看一下CWindow:
0:000> x HYTeris!ATL::CWindow::*
004e1000 HYTeris!ATL::CWindow::rcDefault = struct tagRECT
00442a20 HYTeris!ATL::CWindow::DestroyWindow (void)
00425730 HYTeris!ATL::CWindow::InvalidateRect (struct tagRECT *, int)
00442340 HYTeris!ATL::CWindow::CenterWindow (struct HWND__ *)
00425850 HYTeris!ATL::CWindow::UpdateWindow (void)
0041c950 HYTeris!ATL::CWindow::CWindow (struct HWND__ *)
004391e0 HYTeris!ATL::CWindow::GetDlgItem (int)
004568a0 HYTeris!ATL::CWindow::SetWindowRgn (struct HRGN__ *, int)
00441d20 HYTeris!ATL::CWindow::GetWindowLongW (int)
00444350 HYTeris!ATL::CWindow::Create (wchar_t *, struct HWND__ *, class ATL::_U_RECT, wchar_t *, unsigned long, unsigned long, class ATL::_U_MENUorID, void *)
004391b0 HYTeris!ATL::CWindow::operator HWND__ * (void)
00459080 HYTeris!ATL::CWindow::EnableWindow (int)
00425140 HYTeris!ATL::CWindow::GetClientRect (struct tagRECT *)
00430c70 HYTeris!ATL::CWindow::SetWindowTextW (wchar_t *)
0040eb30 HYTeris!ATL::CWindow::GetWndClassName (void)
00456770 HYTeris!ATL::CWindow::MoveWindow (int, int, int, int, int)
00442ac0 HYTeris!ATL::CWindow::KillTimer (unsigned int)
00455fc0 HYTeris!ATL::CWindow::GetWindowTextW (wchar_t *, int)
0040ba20 HYTeris!ATL::CWindow::IsWindow (void)
00441db0 HYTeris!ATL::CWindow::GetParent (void)
004315b0 HYTeris!ATL::CWindow::SetWindowPos (struct HWND__ *, int, int, int, int, unsigned int)
00456810 HYTeris!ATL::CWindow::GetWindowRect (struct tagRECT *)
00431860 HYTeris!ATL::CWindow::GetStyle (void)
00455250 HYTeris!ATL::CWindow::Invalidate (int)
004318f0 HYTeris!ATL::CWindow::SetCapture (void)
00442cf0 HYTeris!ATL::CWindow::SetTimer (unsigned int, unsigned int, *)
00431980 HYTeris!ATL::CWindow::ModifyStyle (unsigned long, unsigned long, unsigned int)
00443d10 HYTeris!ATL::CWindow::GetDlgItemTextW (int, wchar_t *, int)
0040b980 HYTeris!ATL::CWindow::SendMessageW (unsigned int, unsigned int, long)
00434be0 HYTeris!ATL::CWindow::ShowWindow (int)
004d7a38 HYTeris!ATL::CWindow::`RTTI Base Class Descriptor at (0,-1,0,64)' =
004d7a04 HYTeris!ATL::CWindow::`RTTI Base Class Descriptor at (4,-1,0,64)' =
004d7a20 HYTeris!ATL::CWindow::`RTTI Class Hierarchy Descriptor' =
004d7a30 HYTeris!ATL::CWindow::`RTTI Base Class Array' =
我们看到CWindow只有一份，并且函数数量相比AtlWin.h减少了很多，因为ATL是以源代码的方式提供的，所有没有用到的函数不会被编译到我们最终的可执行文件中。

通过上面的分析，相信我们知道了为什么ATL/WTL大量使用模板，但是生成的exe还是这么小的原因：
不是模板不会使代码膨胀，而是ATL/WTL在设计时就关注了这个问题，它避免了在可能生成很多模板实例的模板类中编写大量代码(有些拗口，不知道你有没有读懂^_^)

总结下，如果你想用模板，但是又不想让自己最终的可执行文件变的很大，有2种方式:
(1)你的模板类不会生成很多模板实例，这样写成模板类还有意义吗
(2)你的模板类的代码量或是函数个数很少，你可以仿照ATL的方式把模板无关的东西逐层剥离。

C++模板会使代码膨胀吗(八)