Re: outcommented fdopen code

On Sat, 12 Jun 1999, Jim Winstead wrote: > On Jun 12, Zeev Suraski wrote: > > On Sat, 12 Jun 1999, Jim Winstead wrote: > > > > > On Jun 12, Zeev Suraski wrote: > > > > On Sat, 12 Jun 1999, Sascha Schumann wrote: > > > > I'm wondering what to do about it myself, since I want to support > > > > include_path and URLs in the C++ version as well (currently it doesn't > > > > work, since I need to create an istream * pointer, and there's no way to > > > > convert a FILE * to an istream *). > > > > > > Well, you could simply derive your own FILEistream or somesuch. > > > It's not very fun, but not incredibly difficult. We had to do > > > something similar on the last project I worked on. > > > > > > I wanted to do it. Would it work though? None of the functions in > > class istream are virtual. Miraculously, and I'm not really sure how, > > istrstream and ifstream don't seem to override any istream functions, just > > add a bit to them, which is why sending ifstream and istrstream pointers > > to flex works. I can't see how flex would work with my own derived class > > that would obviously have to override the various IO functions of istream. > > Since the methods aren't virtual, and since the pointer is always of type > > istream *, it won't call my methods anyway... Or am I missing something? > > > > If I can derive a class from ifstream * it's trivial to write a small > > wrapper class that will relay all of the methods flex calls to a FILE * > > member, but I want to be sure it will be calling these functions, and not > > istream's functions. > > istream derives from something else, which is where the virtual > functions you need to override lay. (If I remember right, it's > actually another class like streambuf or something that is where > most of the implementation lives.) > > I've got a book around somewhere that covers this. I'll see if I > can't dig it up. (Hope I didn't give it to the programmer who > actually did the implementation of that stuff on my last project...) Well, see if you can figure it out. istream's derived from ios, but none of the functions there are virtual either. My C++ is a bit rusty (and frankly, I never used C++ nearly as much as I used C) so I don't think I'd be able to figure it out without a book... If it can be done, it's definitely the best way to do it (this way we can nicely support sockets under Windows as well). Zeev -- ----------------------------------------------------- Zeev Suraski <zeev@zend.com> For a PGP public key, finger bourbon@netvision.net.il