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Re^2: map a hash with a default value or exclude

by GrandFather (Sage)
on Sep 13, 2011 at 03:12 UTC ( #925604=note: print w/replies, xml ) Need Help??

in reply to Re: map a hash with a default value or exclude
in thread map a hash with a default value or exclude

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>;

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

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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>;

    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>;

    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>;

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