Question

I read larbin source code recently. But I have a doubt. I the global.h file define the global class, at the end of this file have a macro like this:

#define setPoll(fds, event) \
global::pollfds[global::posPoll].fd = fds; \
global::pollfds[global::posPoll].events = event; \
global::posPoll++

But in the fetch/fetchPipe.cc file, call this macro like this:

global::setPoll(n, POLLOUT);

The question is why use global:: to call this macro? I think use

setPoll(n, POLLOUT);

is ok. Any body can tell me why?

Answer 1

The source code is a complete mess, it won’t even compile. It seems that global.h has been changed between version 2.2.2 and the current version 2.6.3 without addressing those changes in fetch/fetchPipe.h. Also have a look at those include statements in global.cc:

#include <iostream.h> // iostream.h?
#include <unistd.h>   // twice, see below
#include <errno.h>
#include <string.h>   // mixing C++ and C libraries
#include <sys/types.h>
#include <unistd.h>
    ...

This code is outdated and not standard C++. There are several other things wrong. But back to your question: yes, setPoll(n, POLLOUT); should be sufficient. Using global::setPoll will not result in a bug, since this will expand to

global::global::pollfds[global::posPoll].fd = fds;
global::pollfds[global::posPoll].events = event;
global::posPoll++;

and global is a struct (see Mike Seymour’s comment).