in reply to Re: Re: Re: Help with recurring "uninitialized variable" problem.
in thread Help with recurring "uninitialized variable" problem.

>B::Deparse can shed some light . . .

This is a Perl module? Sorry, this statement doesn't make much sense to me yet. 

>$ perl -MO=Deparse,-p -e '$one_line =~ !/^#+/'
>($one_line =~ (not /^#+/));

[download]
>So what you were really doing was first matching /^#+/ against $_,

Why is that? Doesn't the =~ operator mean that I'm matching against whatever is to the left of the operator? Was it matching against $_ because of where I put the "not" operator(!)?

>taking the logical not of what that returned and then attempting to use the string version of that as a regexp to match against $one_line.

I guess I wish I understood this better. I'll keep at it.

Charles Thomas
Madison, WI

Replies are listed 'Best First'.
Re: Re: Re: Re: Re: Help with recurring "uninitialized variable" problem.
by Fletch (Bishop) on Apr 09, 2004 at 22:24 UTC

    B::Deparse tells perl to spit back what it parsed your code as, optionally adding parens which you may have omitted to make precedence clearer.

    As for =~, it does say match against what's on the left hand side; the problem in this case is that what you had on the right hand side wasn't a simple m// so it was treated as an expression yielding a regexp object as if you'd used qr//. In other words, what you did was more: 

    $foo = /^#+/;    # match against $_. a false '' since you never set $_
$bar = not $foo; # take the logical opposite, so always "1"
$baz = qr/$bar/; # make a regep object from the contents matching "1"
$one_line =~ m/$baz/; # returns true if $one_line has a 1

    [download]
[reply]
[d/l]

In Section Seekers of Perl Wisdom