Parsing attributes in one line using map

After writing this code, I realized many people may have just not realized this is possible, so I think posting it here would make people think more about it.

I was writing a simple script wich would receive a attr=value,attr2=value2 string and automatically I wrote:

my %attrs = map { split /=/ } split /,/, $attr;
[download]

Well, the trick is that map doesn't have to return the same number of elements of the list it receives. If you returns a list inside a map, the resulting list will have more elements than the input list.

This sounds very intuitive to me, but maybe it's not for others...

daniel

Comment on Parsing attributes in one line using map Download Code

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Re: Parsing attributes in one line using map by izut (Chaplain) on Sep 25, 2006 at 10:34 UTC
You can do this (borrowed from 'Perl for System Administrators'): `my %attrs = split /=\|,/, $attr;` [download] Igor 'izut' Sutton your code, your rules.	[reply] [d/l]
Re: Parsing attributes in one line using map by davidrw (Prior) on Sep 25, 2006 at 12:44 UTC
Returning more (or less even) elements than provided is very natural for map and very commonly used, especially for generating hashes .. here's two relatively trivial examples: `perl -MData::Dumper -le 'my %cubes = map { $_ => $_**3 } 1..4; print D +umper \%cubes' $VAR1 = { '1' => '1', '2' => '8', '3' => '27', '4' => '64' }; my @users = [ {id=>4324, name=>'blah'}, {id=>1234, name=>'stuff'}, {id +=>5678, name=>'foo'} ]; my %usersByName = map { $_->{id} => $_ } @users; my $id = prompt_for_user_id; my $user = $usersByName{$id};` [download] Also, see map for more examples (including the basic hash creation), and this quote: Evaluates BLOCK or EXPR in list context, so each element of LIST may produce zero, one, or more elements in the returned value.	[reply] [d/l]
Re^2: Parsing attributes in one line using map by jhourcle (Prior) on Sep 25, 2006 at 13:38 UTC
Returning more (or less even) elements than provided is very natural for map and very commonly used, especially for generating hashes .. For those not familiar with returning less -- use an empty list `()`. To build on davidrw's example: `perl -MData::Dumper -le 'my %oddcubes = map { $_%2 ? ($_ => $_**3) : ( +) } 1..9; print Dumper \%oddcubes' $VAR1 = { '1' => 1, '3' => 27, '7' => 343, '9' => 729, '5' => 125 };` [download]	[reply] [d/l] [select]
Re: Parsing attributes in one line using map by jdporter (Paladin) on Sep 25, 2006 at 14:53 UTC
`split /=/` [download] should be `split /=/, $_, 2` [download] But what if any of the values contains `','` or `'='`? `my %attrs = $attr =~ /([^=,]+)=(.*?)(?:(?=,[^=,]+=)\|$)/g;` [download] We're building the house of the future together.	[reply] [d/l] [select]


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