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Re^4: How to localize conditionally? (tias)

by ikegami (Pope)
on Mar 14, 2011 at 16:07 UTC ( #893100=note: print w/replies, xml ) Need Help??

in reply to Re^3: How to localize conditionally? (tias)
in thread How to localize conditionally?

No, but how can one assign to a hash element that does not exist? Well, %ENV is magical, so let's test it out.

$ perl -wE' my $condition = 0; say exists($ENV{BLAH}) || 0; local $ENV{BLAH} = $condition ? 42 : $ENV{BLAH}; say exists($ENV{BLAH}) || 0; ' 0 1

So I was right

This is perl 5, version 12, subversion 2 (v5.12.2) built for i686-linu +x

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Re^5: How to localize conditionally? (tias)
by tye (Sage) on Mar 14, 2011 at 16:18 UTC

    My tests appeared to work for strange reasons. Sorry about that. But you can fix the original without copying the whole environment:

    local $ENV{BLAH}; if( @ARGV ) { $ENV{BLAH}= 42; } else { delete $ENV{BLAH}; }

    - tye        

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