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Re: Applying a regular expression to a string

by BazB (Priest)
on Apr 04, 2005 at 11:46 UTC ( #444630=note: print w/ replies, xml ) Need Help??


in reply to Applying a regular expression to a string

Try something like:

my $message_id = $1 if $message =~ m/([\w\d]+)\s+.*/;

If the information in this post is inaccurate, or just plain wrong, don't just downvote - please post explaining what's wrong.
That way everyone learns.


Comment on Re: Applying a regular expression to a string
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Re^2: Applying a regular expression to a string
by Smylers (Pilgrim) on Apr 04, 2005 at 13:22 UTC
    my $message_id = $1 if $message =~ m/([\w\d]+)\s+.*/;

    Putting my (a compile-time directive) with an if statement modifier (which can only take place at run-time) is confusing, and therefore deprecated.

    Also, there's no point at all in having .* at the end of the regexp: since one of the things it would happily match is nothing, it isn't making any restrictions at all about what can follow the \s+, so is just adding noise.

    Finally, the \w class already includes digits, so writing [\w\d] doesn't add anything.

    Here's how I might have written this:

    $message =~ /^(\w+)/ or die "Message '$message' doesn't start with an identifier.\n"; my $message_id = $1;

    die might not be the most appropriate thing to do here; adjust as appropriate. But if you're adamant that $message could never not match the pattern, then a die test is better than nothing: if you're right, then it'll never happen, and if you're wrong then your assumption was wrong so there's a problem elsewhere and at least you found out about it.

    Smylers

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