Stumped by regex

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

Hi,
The current Inline/C/Makefile.PL (http://search.cpan.org/src/INGY/Inline-0.44/C/Makefile.PL) begins with the following code:

use strict;
use ExtUtils::MakeMaker;
use Config;
use File::Spec;

my ($cc, $exe) = @Config{'cc', '_exe'};
$cc =~ s/\s+-.+$//; #remove possible trailing options

my $found = 0;
my $delim = $^O eq 'MSWin32' ? ';' : ':';
if ($cc =~ m|/:\[|) {
    $found = -f "$cc$exe";
}
else {
    for my $lib (split $delim, $ENV{PATH}) {
    $found = -f File::Spec->catfile($lib,"$cc$exe") and last;
    }
}
[download]

I have difficulty working out how $cc will ever match |/:\[| - can someone here provide some insight into the point of that test ?

Cheers,
Rob

Comment on Stumped by regex Select or Download Code

Replies are listed 'Best First'.
Re: Stumped by regex by JavaFan (Canon) on Nov 10, 2008 at 11:43 UTC
Considering that $cc comes from %Config, it could technically contain anything. For instance, it may contain `"/foo/bar/:[baz]"`. Now, while the latter is valid in most Unix file systems, it's highly unlikely to find a C compiler in such a path. Unlike VMS. A full path in VMS consists of a device name, a directory, a file name (including extension), and a version number. The device name and the directory are separated by a colon, while the directory itself is enclosed in square brackets. Which explains not only that $cc may match this, but also why this specific match was choosen.	[reply] [d/l]
Re^2: Stumped by regex by syphilis (Archbishop) on Nov 10, 2008 at 21:25 UTC
Thanks guys. Let's hope I don't ever have to get involved with VMS porting issues :-) Cheers, Rob	[reply]
Re^3: Stumped by regex by ikegami (Patriarch) on Nov 10, 2008 at 22:33 UTC
VMS is actively supported by people on the p5p list. They might be willing to help you if you have a VMS concern.	[reply]
Re^3: Stumped by regex by blazar (Canon) on Nov 11, 2008 at 11:49 UTC
I personally believe that in case you do, then you will fully understand why modules like File::Spec exist, and how useful they are. `--` If you can't understand the incipit, then please check the IPB Campaign.	[reply] [d/l]
Re: Stumped by regex by ikegami (Patriarch) on Nov 10, 2008 at 11:17 UTC
I bet it's related to VMS.	[reply]


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