in reply to Re^2: ChainMap of Hashes on CPAN?
in thread ChainMap of Hashes on CPAN?

It's useful to avoid the overhead of concatenating very long hashes if you only need few lookups.

Then I think I'd use:

my $thing;
exists $_->{ $key } and $thing = $_->{ $key } for \(%hash1, %hash2, %h
+ash3);

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and save constructing a whole (class of) objects for something so trivial.

But, I don't ever remember having such a requirement; nor can I think of an actual use-case.

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Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
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Re^4: ChainMap of Hashes on CPAN?
by LanX (Saint) on Mar 23, 2013 at 18:42 UTC
    Well your code has a logical flaw and a typo.

    And I already explained that I would probably do something similar.

    Cheers Rolf

    ( addicted to the Perl Programming Language)

    UPDATE:

    this works:

    exists $_->{ $key } and $thing = $_->{ $key },last for \(%H1, %H2);

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[d/l]
      Well your code has a logical flaw and a typo.

      Obviously untested, but the point was that I cannot see the purpose for a subroutine, never mind a whole class for such a purpose.

      I've found this kind of thing very prevalent in Python (& ruby) code that I've converted in the past.

      You get a whole bunch of classes to implement some algorithm; but when you strip away the boiler place and make-work, you end up with one or two lines from each class actually doing useful work. (In Perl at least.)

      With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
        ties are slow so no problem using a custom class.

        And you only implemented the lookup.

        I don't think it's worth making this core like they did for Py3, but having a well documented module on CPAN seems more efficient than writing, documenting and testing own code.

        I'm a big fan of lazy data structures and having such a tool in the box always opens the path to new uses cases.

        At least this way seems appropriate if one of the chained hashes is itself a tied structure.

        Cheers Rolf

        ( addicted to the Perl Programming Language)

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[d/l]
Re^4: ChainMap of Hashes on CPAN?
by McA (Priest) on Mar 23, 2013 at 18:38 UTC

    I there a typo?

    McA

[reply]

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