Interpretation of a line needed.

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Interpretation of a line needed. by Abigail-II (Bishop) on Sep 23, 2003 at 16:05 UTC
It's a difficult, and inefficient way of writing: `next if $field eq "Name" or $field eq "Phone";` [download] Abigail	[reply] [d/l]
Re: Re: Interpretation of a line needed. by freddo411 (Chaplain) on Sep 23, 2003 at 17:36 UTC
Good Lord, ++ parent message. Abigail's version is so much easier to read. ------------------------------------- Nothing is too wonderful to be true -- Michael Faraday	[reply]
Re: Interpretation of a line needed. by broquaint (Abbot) on Sep 23, 2003 at 15:46 UTC
It's basically creating a temporary hash and testing if `$field` `exists` in the hash. So `map { $_ => undef } qw(Name Phone)` [download] Create a list of key value pairs from the given list where the keys are each element of the list and values are `undef` `{ map { $_ => undef } qw(Name Phone) }` [download] Populate an anonymous hash with the list that was created from the `map` `exists { map { $_ => undef } qw(Name Phone) } -> { $field };` [download] Check for the existence of `$field` in the anonymous hash reference. Perl Idioms Explained - keys %{{map{$_=>1}@list}} may also be of help. HTH `_________ broquaint`	[reply] [d/l] [select]
Re: Re: Interpretation of a line needed. by Anonymous Monk on Sep 23, 2003 at 16:32 UTC
Thanks all!	[reply]
Re: Interpretation of a line needed. by zby (Vicar) on Sep 23, 2003 at 15:54 UTC
The result of this code: `{map {$_ => undef } qw(Name Phone)}` is this structure: `{ "Name" => undef, "Phone" => undef}` [download] Then it is checked if `$field` is a key in this structure. More precisely what I called here a structure is a pointer to an anonymous hash. Thats why the `exists` function can be used. Hope that explains how it works. But I what I can't explain is why is it so obfuscated.	[reply] [d/l] [select]