Re: Re: Re: Finding part of a file

You can nest reads on an open filehandle. I didn't know
this until looking at your code and playing with it a little;
here's what I got.

#!/usr/bin/perl

$begin='banana';
$end='grape';

while(<DATA>) {
  /$begin/ ? eval { /$end/ ? last : print while (<DATA>) }
           : next
}
 
__DATA__
apple
banana
pear
peach
grape
prange
[download]

blyman

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Re4: Finding part of a file by blakem (Monsignor) on Dec 05, 2001 at 13:15 UTC
That code produces the warning: `Exiting eval via last at line 8, <DATA> line 5.` [download] when warnings are turned on.... I'm not entirely sure why 'last'ing out of an eval block is bad, but I do know that eval is overkill for what you've written. `do` is probably more appropriate. The following code issues no warnings: `#!/usr/bin/perl -wT use strict; my $begin='banana'; my $end='grape'; while(<DATA>) { /^$begin$/ && do { /^$end$/ ? last : print while (<DATA>) } } __DATA__ apple banana pear peach grape orange` [download] Update: You might want to replace the `last` above with a `next` if you want multiple windows to print... For instance, it changes what gets printed using this data: `__DATA__ banana pear peach grape orange banana cow pig grape` [download] Notice that 'cow' and 'pig' are between a second set of on/off toggles... `last` will skip them `next` will print them. Which is the desired behavior? Your guess is as good as mine. -Blake	[reply] [d/l] [select]
Re: Re4: Finding part of a file by belden (Friar) on Dec 05, 2001 at 22:54 UTC
Yep, there's a reason I didn't include warnings in my code snippet :) Going to have to read up on eval vs die and figure out why eval is overkill in this case... Interestingly enough, I can goto outside of an eval block without any complaints: `#!/usr/bin/perl use strict; use warnings; my $begin='banana'; my $end='grape'; while(<DATA>) { /$begin/ ? eval { /$end/ ? goto END : print while (<DATA>) } : next } END: exit; __DATA__ apple banana pear peach grape orange` [download] ...re your update - that's a neat trick that I'll have to tuck away. blyman	[reply] [d/l]