in reply to Consise way to filter out keys with undef values from a hash slice?

This

>  grep { $args{$_ } } keys %ta;

Will also delete all false values like 0 or "" . You rather want to test on definedness and not truth

This keys on a slice

>   keys %args{'profile', 'user', 'password'};

Is over complicated and doesn't make sense.

You obviously just want the list of keys directly

'profile', 'user', 'password'

But I concur with choroba that using exists right from the beginning is the cleanest way, since undef could be a legal value.

edit

There is - unfortunately - no "slice when exists" operator in Perl.

Otherwise (ab)using hashes for set operations like intersections would be trivial.

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

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Re^2: Consise way to filter out keys with undef values from a hash slice?
by LanX (Saint) on Jun 01, 2020 at 22:00 UTC
    On a side note,

    I was surprised that the following is even legal syntax. I only knew slicing lists with @

    >  %args{'profile', 'user', 'password'};

    Turns out it was introduced with 5.20 and returns a list of key/value pairs.

    Cheers Rolf
    (addicted to the Perl Programming Language :)
    Wikisyntax for the Monastery

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Re^2: Consise way to filter out keys with undef values from a hash slice?
by jo37 (Curate) on Jun 02, 2020 at 19:05 UTC
    Otherwise (ab)using hashes for set operations like intersections would be trivial.

    Though off-topic here: Is there a common idiom for an intersection of two hash-sets? The first thing that comes to my mind is something like: 

    %a_b = map {exists $b{$_} ? ($_ => $b{$_}) : ()} keys %a;

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    Greetings,
    -jo

    $gryYup$d0ylprbpriprrYpkJl2xyl~rzg??P~5lp2hyl0p$
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