"Dr.Ruud" <rvtol+use...@isolution.nl> writes:
> Harry Putnam wrote:
>
>> my $date_re = qr/^Date:/;
>> my $other_re = qr/^Date: some date/;
>>
>> if (/$date_re/ !~ /$other_re/){
>
> That code is bizar!
>
> What exactly do you want to compare?
> 1. Whether both matches succeed in the same way?
> 2. Whether both regexps contain similar code?
> 3. none of the above
I guess 2 is closest, but Jim got me lined out a bit on that.
The snippet is simplified and from a larger script that searches
mail/news headers for a regex given on the command line. It returns
the line containing the regex plus the line containing ^Date: and the
absolute filename of the file where match occurred.
Then when a blank line shows up, if a hit has occurred it prints the
desired output, then lasts out of while loop and goes on to the next
file in a find() function.
What that code attempted to do was prevent the script from returning
two Date lines, in the event the regex given on command line was also
a Date regex.
As Jim G, said its never necessary to match two regex against each
other, and especially when perl is expecting the match to be aimed at
$_.
On my possibly wrong understanding of Jim G's advice I fixed the
`bizarre' mess by making the match aim at $_ like this:
if(/$date_re/ && ! /$other_re){
$dateline = $_;
}
In that case both possible matches are aimed at $_ and collecting two
Datelines is prevented.
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