Re: map a hash with a default value or exclude

In the spirit of TIMTOWTDI, here's a method that involves capturing your split() output in an arrayref:

... map { chomp; [split'=']; } <$fh>;
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which is subsequently filtered through a second map():

%{$self->{info}} = map { EXPR } map { chomp; [split'=']; } <$fh>;
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To exclude a key, EXPR is:

    defined $_->[1] ? @$_ : ()
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To use a default value (here I've used the string: undef), EXPR is:

    $_->[1] //= q{undef}; @$_
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-- Ken

Comment on Re: map a hash with a default value or exclude Select or Download Code

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Re^2: map a hash with a default value or exclude by GrandFather (Saint) on Sep 13, 2011 at 03:12 UTC
or instead of using the ?: in the "decoding" map for the elimination case you could instead use a grep: `%{$self->{info}} = map {@$_} grep {defined $_->[1]} map {chomp; [split +'='];} <$fh>;` [download] In any case generating the array ref doesn't actually seem to be a win in terms of succinctness or comprehensibility. True laziness is hard work	[reply] [d/l]
Re^3: map a hash with a default value or exclude by PrakashK (Pilgrim) on Sep 13, 2011 at 19:09 UTC
Yet another way, using the 3-argument form of split, which guarantees that the input string is split into two parts and no more or less. The second part would be a string of length 0, instead of an undefined value. `%{$self->{info}} = map {@$_} grep {$_->[1]} map {chomp; [split '=', $_ +, 2];} <$fh>;` [download] I prefer this form of split in handling `key=value` type strings, since it handles the cases where a value could have an embedded '=' (`PASSWORD=blah=argh!`), whereas the shorter one-(or, two-)argument forms would return truncated values. Yet another alternative, using only one map: `%{$self->{info}} = map {chomp; my ($k, $v) = split '=', $_, 2; $v ? ($ +k => $v) : (); } <$fh>;` [download] If we want to supply default values: `# assuming default values are in %defaults %{$self->{info}} = map {chomp; my ($k, $v) = split '=', $_, 2; $k => $ +v \|\| $defaults{$k}; } <$fh>;` [download]	[reply] [d/l] [select]