[Playerstage-developers] replacement functions

[Brian G. <ge...@ai...>]

hi,

This is a general note on the use of replacement functions in Player
drivers.

Some useful functions are not available on all platforms.  Sometimes we can
get by without them, but sometimes we really need them.  For cases like
this, Player includes implementations of some functions (usually stolen
from glibc) that are compiled into a replacement library and are used when
those functions are not available in the system libs.

Currently, Player's replacement lib has implementations of:

   - alphasort()
   - dirname()
   - poll()
   - scandir()
   - cfmakeraw()

If you use any of these functions, then you should #include "replace.h"
(it's in $(top_srcdir)/replace); where necessary, the replacement
functions will be used.

For poll() in particular, do NOT #include <sys/poll.h>, because it's not
available everywhere.  Just #include "replace.h" and you can call poll()
as usual.

In general, we don't know when a replacement function is necessary
until somebody reports a broken compile on another system.  But you can
help by always reading the "CONFORMING TO" section of the man page for
the function in question.  The best case is when the function conforms
to POSIX.  When you have a choice, always use POSIX-endorsed functions,
because they're available pretty much everywhere.  And if you know you're
using a function that's not widely available, let me know so that we
work out a replacement mechanism.

         brian.

-- 
Brian P. Gerkey                    ge...@ai...
Stanford AI Lab                    http://ai.stanford.edu/~gerkey