Preprocessor Problems

[Dave Brolley]

Generally, this kind of misuse is an attempt to delay the pre-expansion 
of a macro argument. This can be necessary if the argument is a macro 
name intended to be pasted at the next nesting level. There are 3 
portable solutions that I see:

1) Move the pasting out of ETEMPLATE to within the invocation of ETEMPLATE
2) Define the macro named in the argument as function-like so that it 
doesn't get pre-expanded before being passed to ETEMPLATE
3) pass the name in pieces and paste it in the invocation of ETEMPLATE

Solution  3) would require changes to the way these macros are used and 
it appears that this is a well known library of macros.

In any case, Neil is right. The usage below is unportable and gcc is 
correct to warn about it.

Dave

Neil Booth wrote:

> Alexy Khrabrov wrote:-
> Content-Description: message body and .signature
> 
>> ETEMPLATE(##ctypes) class name; \
>> ETEMPLATE(##ctypes) \
> 
> 
> This kind of stuff is not portable.  Why do you need the ##?  Just
> remove it, and probably everywhere else it is complained about.  You
> cannot paste anything with a '('; shame on other preprocessors for not
> telling you so.
> 
> Neil.
> 
>