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Re: Is there a module for object-oriented substring handling/substitution?

by choroba (Abbot)
on Jan 24, 2013 at 23:21 UTC ( #1015244=note: print w/ replies, xml ) Need Help??


in reply to Is there a module for object-oriented substring handling/substitution?

Do you know that a reference to substr works as you described?

my $string = 'abcdefghijklmnopqrstuvwxyz'; my $substring = \substr $string, 10, 10; $$substring = uc $$substring; print $string, "\n";
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Comment on Re: Is there a module for object-oriented substring handling/substitution?
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Re^2: Is there a module for object-oriented substring handling/substitution? (2 substrs)
by tye (Cardinal) on Jan 25, 2013 at 01:57 UTC
    Do you know that a reference to substr works as you described?

    Only if you use a single substring. I have a partially-written module that does this type of thing and supports multiple simultaneous substrings of the same string such that they cooperate (which leads to some tricky bits which were fun to hash out).

    But tye having an unpublished module isn't really a reason to avoid writing one's own version of something similar.

    - tye        

      They long since lifted the 'only one lvalue ref' limitation. This is 5.10.1:

      $s = 'abcdefghijklmnopqrstuvwxyz';; @r = map \substr( $s, $_*4, 2), 0..6;; $$_ = uc $$_ for @r;; say $s;; ABcdEFghIJklMNopQRstUVwxYZ say $];; 5.010001

      It does have its limitations though. (Unsurprisingly) The lvalue refs do not adjust to accommodate replacements that alter the length of the string:

      $$_ = $_ for @r;; say $s;; REF(REF(REF(REF(REF(REF(REF(0x3e82050)3e821e8)3e82260)3e820e0)11c458)3 +e820c8)335dc0)cdEFghIJklMNopQRstUVwxYZ

      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.
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        [ Update: The end of the post I replied to, starting at "It does have its limitations though" was not present when I replied (nor during the several times I had reason to load a page that included that node during the time I took composing my reply -- I don't believe it was even present immediately after I replied; though I am less sure of that). FYI. ]

        Do you know that a reference to substr works as you described?
        Only if you use a single substring.
        They long since fixed the 'only one lvalue ref' limitation.

        Thanks for the notice, but that isn't what I was talking about. Being able to have more than one lvalue substr ref doesn't itself result in "multiple simultaneous substrings of the same string such that they cooperate" nor to them "working as the OP described". (Nor does it lead to any particularly "tricky bits", certainly not any that qualify as "fun to hash out".)

        #!/usr/bin/perl -w use strict; my $s = 'one,two,three,four'; my @p; while( $s =~ /([^,]+)/g ) { push @p, \substr( $s, pos($s)-length($1), length($1) ); } print "($$_)" for @p; print " [$s]\n"; ${$p[0]} = 'five'; # Change 'one' to 'five' ${$p[2]} = 'X'; # Change 'three' to 'X' print "($$_)" for @p; print " [$s]\n"; print $], $/; __END__ (one)(two)(three)(four) [one,two,three,four] (five)(,tw)(X)(r) [five,twoXe,four] 5.012000

        While the OP was requesting an outcome like:

        (five)(two)(X)(four) [five,two,X,four]

        Note that I'm not trying to argue that \substr magic should be taught to "cooperate". What \substr magic does is quite simple and sane and I see no reason to change it. It just doesn't match what the OP was asking for (nor what my module implements).

        - tye        

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