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<P ALIGN=CENTER><EM>Posted by <STRONG><A HREF="mailto:winkler1@iname.com">Jeff Winkler</A></STRONG> on <STRONG>4/24/98 2:58p.m.</STRONG></EM></P>
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<P>Smart Folks ...
<P> I'm attempting to write a templatized function which takes a CObject-derived pointer type, using templates to be typesafe and avoid casting (well, do it in one place, the blessed way). Header file:
<P>&gt;&gt; class CMyClass {
<BR>&gt;&gt; public:
<BR>&gt;&gt;  template &lt;class T&gt; BOOL GetNext ( T **pObj )
<P>So far, so good, GetNext will compile with a do-nothing body such as
<BR>&gt;&gt; { *pObj = (T *) NULL; return true; }
<P>**Here's where things get interesting: to reduce the amount of templatized code, I'd like to extract and pass the CRuntimeClass into a common method.  MFC does this with RUNTIME_CLASS, which has a funky ## concat macro to generate a unique name.
<P>&gt;&gt; #define RUNTIME_CLASS(class_name) ((CRuntimeClass*)(&amp;class_name::class##class_name))
<P>* I then tried to use the macro 
<BR>&gt;&gt; template &lt;class T&gt; BOOL GetNext ( T **pObj ){ return RealGetNext(RUNTIME_CLASS (pObj), (CObject **) pTObj); }
<P>Calling GetNext with a CStudent * gives the following error (*'s are mine):
<BR>  &gt;&gt; error C2039: '**classT**' : is not a member of '**CStudent**'
<P>So, my class name wasn't substituted for T in the data member, though it was for the class name.  Gotta love C++, plenty of rope :).. 
<P>Anyone know a way to defer evaluation of ## macro sequence until after the templates? I've tried different macro sequences but they always finish before T has a value.  Alternatives at this point are RTTI or straight macro calls (yech).
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<P><UL><LI><STRONG><A HREF="read.cgi-read=10371.htm" tppabs="http://www.codeguru.com/mfc_bbs/read.cgi?read=10371">correction</A></STRONG> : Jeff Winkler -- <EM>4/24/98 3:03p.m.</EM>
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