Re: question about r8708 (Perl warning pragmas)

On Tue, Mar 02, 2004 at 11:57:49PM -0600, kfogel@collab.net wrote:
> r8708 applies a patch like this to three Perl hook scripts:
>
> -# The warning switch is set here and not in the shebang line above
> -# with /usr/bin/env because env will try to find the binary named
> -# 'perl -w', which won't work.
> -BEGIN
> - {
> - $^W = 1;
> - }
> -
> +require 5.6.0; # minimum Perl version for "warnings" module
> +use warnings;
>
> Some time ago, Ben Collins-Sussman and I looked at this and wondered
> why the "require 5.6.0;" line wasn't controversial.

For an entirely separate reason than the version requirement itself,
'require 5.6.0;' isn't a very good idea. Here's why:

  $ perl -MConfig -le 'print $Config{version}'
  5.00503
  $ perl -e 'require 5.6.0;'
  Can't locate 5.60 in @INC (@INC contains: /usr/lib/perl5/5.005/i386-linux /usr/lib/perl5/5.005 /usr/local/lib/site_perl/i386-linux /usr/local/lib/site_perl /usr/lib/perl5 .) at -e line 1.
  $ perl -e 'require 5.006;'
  Perl 5.006 required--this is only version 5.00503, stopped at -e line 1.

Versions older than 5.6.0 didn't understand the "5.6.0" syntax for
versions, so you should use the "5.006" form instead. Both will fail,
but the former gives a very confusing and misleading error message.

-- 
Colin Watson                                  [cjwatson@flatline.org.uk]
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