Playing nice with $_ in ExtUtils::Manifest

Hey,

Unfortunately perl doesn't automatically localize $_ when using 'while 
(<fh>) {...}'.  Witness this one-liner:

   % perl -MO=Deparse -e 'while(<>) {print}'
   while (defined($_ = <ARGV>)) {
       print $_;
   }

So it'll clobber $_ with undef at the end of the block, and if $_ is 
read-only then it'll fail with an error.

I recently ran across this when I got some death-errors in calling some 
of the ExtUtils::Manifest functions from Module::Build.  Those 
functions fail if $_ contains an alias to a read-only variable:

   % perl -MExtUtils::Manifest=maniread -e 'foo(5); sub foo{for(@_) 
{maniread}}'
   Modification of a read-only value attempted at 
/Library/Perl/ExtUtils/Manifest.pm line 185.

The solution is to put "local $_;" before a few while(<fh>) loops in 
ExtUtils::Manifest.

I'd submit a real patch, but:

  % cvs up
  cvs [update aborted]: connect to makemaker.org:2401 failed: Connection 
refused

  -Ken

• Playing nice with $_ in ExtUtils::Manifest by Ken Williams
• Re: Playing nice with $_ in ExtUtils::Manifest by Michael G Schwern