An interesting idea and certainly much less work
However, as I understand it, you're suggesting limiting the wildcards simply to ensure that the filtered_directory_iterator behaves the same on posix and windows systems?
No. The main reason was to have a simple iterator for simple (and what I think is the most common) cases which also avoid the need to go via a list.
Of course that is possible, but my suggestion gives windows users the full power of glob().
So did I but I put it into a separate iterator where you can define the rules completely independent of the filesystem.
Don't you ever search for things like "[a-d]*.{cxx,hpp}"?
I do it in the shell but I have never had the need to do it inside an application. I'm sure there are such applications.
Sorry, but I don't see why such a proposal is an improvement.
Also, how do you limit the wildcards? I take it you don't, but that the underlying matcher (findfirstfile, glob) will behave differently on receipt of the same pattern.
The filesystems already behave differently since one is case-sensitive and the other is not. Anyway, I think it is reasonable to limit the wildcards to some portable syntax e.g. max 2 '*' are allowed and they must either be the last character or followed by a '.'.