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Postings from June 2009
2009/6/23 Paul Fenwick <pjf@perltraining.com.au>:
> Having said that, I just tried:
>
> perl -MO=Deparse -Mautodie=readline -e'while (<STDIN>) { print };'
>
> and got:
>
> use autodie (split(/,/, 'readline', 0));
> BEGIN {
> $^H{'guard Fatal'} = q(ARRAY(0x12d4a60));
> }
> while (&readline(STDIN)) {
> print $_;
> }
> -e syntax OK
>
> That reveals that it's able to catch readline (so clearly I haven't been
> trying hard enough), but it loses its magic ability of setting $_ inside a
> while loop. I would have expected the deparsed output to be:
>
> while( defined($_ = &readline(STDIN) ) ) {
> print $_;
> }
>
> While one could argue that's a bug, fixing for newer versions of Perl won't
> help the existing 5.8/5.10 install base upon which autodie presently works.
> If someone can give me pure-perl magic that allows me to detect if
> readline() is being called inside a while loop, then I'd appreciate it, as I
> can't think of any way off the top of my head.
Indeed, Perl_newWHILEOP adds a defined() and a "$_=" if it sees the
original readline op. There is currently no way of telling whether a
subroutine call comes from an overriden readline, pure-perl or not.
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