overwrite builtin functions ( system, chdir )

borisz has asked for the wisdom of the Perl Monks concerning the following question:

Hi,
I like to overwrite system and chdir for debuging purpose. But I can't get it to work.
I tried so far:

*CORE::GLOBAL::system = sub { print "system\n" };
*CORE::GLOBAL::chdir = sub { print "chdir\n" };
*CORE::GLOBAL::glob = sub { print "glob\n" };

glob; chdir; system
__OUTPUT__
glob
[download]

I wonder why this works for glob, but not for chdir, system, chr and ord. Whats wrong with my code?

Boris

Comment on overwrite builtin functions ( system, chdir ) Download Code

Replies are listed 'Best First'.
Re: overwrite builtin functions ( system, chdir ) by ysth (Canon) on Apr 04, 2005 at 13:46 UTC
Perl needs to know that you want to override a builtin at the time it compiles the code that calls the builtin. Put your *CORE::GLOBAL:: assignments in a BEGIN block.	[reply]
Re^2: overwrite builtin functions ( system, chdir ) by borisz (Canon) on Apr 04, 2005 at 13:50 UTC
Thanks, that work fine! Boris	[reply]
Re: overwrite builtin functions ( system, chdir ) by ktross (Deacon) on Apr 04, 2005 at 13:16 UTC
Would something like this do? `use subs 'system','chdir','glob'; glob; chdir; system; sub system {print "system\n"} sub chdir { print "chdir\n" } sub glob { print "glob\n" }` [download] __OUTPUT__ glob chdir system	[reply] [d/l]
Re^2: overwrite builtin functions ( system, chdir ) by borisz (Canon) on Apr 04, 2005 at 13:33 UTC
Hi, No, that is not enough, I like to overwrite the functions global regardless of the namespace. So that this work: `CORE::GLOBAL::system = sub { print "system\n" }; CORE::GLOBAL::chdir = sub { print "chdir\n" }; *CORE::GLOBAL::glob = sub { print "glob\n" }; package xyz; glob; chdir; system` [download] Boris	[reply] [d/l]