http://www.perlmonks.org?node_id=1027522


in reply to Re^3: check parameters
in thread check parameters

What is wrong with the code hdb gave you?

That code does not have the problem your code has, so why are you not using it?

As a hint, a string is always true in Perl. And your code simply constructs a string but never matches against it:

...
if ("(".join('|', @{$opts->{params}}).")" # This constructs a string
    and !grep { /^$_/i } keys %$format)   # and this matches $_ agains
+t itself
...

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Re^5: check parameters
by hdb (Monsignor) on Apr 08, 2013 at 14:41 UTC

    ag4ve, can you pls state what you want to achieve? Here is what happens step-wise: 

    my $pattern ="(".join('|', @{$opts->{params}}).")";
# pattern is now "(a|b)"

my @test =  grep { /^$pattern/i } keys %$format;
# @test = ( "bar", "abc" )

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    !grep... puts grep into scalar context, ie it will return 2, the length of @test above. !2 is false therefore your "if" block will not be executed.

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