Eric Niebler schrieb:
Stefan Strasser wrote:
michael toksvig schrieb:
BOOST_FOREACH(pair<Key, Value> &p, some_map)
does not work, since the preprocessor just can't get over that first comma
this could be worked around with C99 variadic macros if available, something like:
Clever, but there is an ambiguity here. What is the relations of the arguments in BOOST_FOREACH2(a1,a2,a3)? Do a1 and a2 together make up the loop variable declaration, or do a2 and a3 together form the collection expression:
case 1: BOOST_FOREACH( std::pair<int,int> p, some_map )
case 2: BOOST_FOREACH( int i, some_trait<this,that>::some_list() )
right, haven't thought of that. but I still think the workaround is convenient because - case 1 is more common than case 2 - both cases fail without workaround - the user can workaround case 2(parens), but can't case 1(at least, not easily, without typedef)
Anyway, I haven't heard of a major C++ compiler supporting C99 varargs. Is there one? I don't think we have a config macro for detecting it.
gcc and intel support it by default, como does with --c99 don't know about others, but 3 major ones are a good deal. -- Stefan Strasser