From: "boris_stitnicky (Boris Stitnicky)" <boris@...>
Date: 2012-05-26T06:48:06+09:00
Subject: [ruby-core:45243] [ruby-trunk - Feature #1873] MatchData#[]: Omits All But Last Captures Corresponding to the Same Named Group


Issue #1873 has been updated by boris_stitnicky (Boris Stitnicky).


Hi everyone. I am a newbie user of computer languages (< 1 year), and I am
providing my feedback from this position.

Summary:
I find that this feature proposal is basically an extension of Regex state
machine functionality. I am against it. I think, that the current behavior
is natural: When one uses the same capture group name again, the old value
is lost, just like when one assigns a new value to the same variable name.
In Regex machine, I value simplicity and memorizeability over abundance of
features. Moreover, as runpaint points out himself, this feature is really
not missing: "lost" captures are available via #to_a and #capture methods.

Rationale:
As a newbie, I still remember hard time that I had learning Regex. I find
the learning overhead for Ruby acceptable to make it usefull as a tool for
people, who are not programmers by profession. But I found that to actually
solve even simple domain-specific programming tasks, one has to also learn
seemingly endless list of formats, sub-standards, sub-languages, programers'
editors and other idiosyncrasies, which in total take much greater effort
that learning Ruby itself. Regex is one of these sub-languages.

The idea of a simple state machine that performs matching tasks far beyond
find & replace comes as very natural to me. I might have learned Regex in
1 hour in good old days when it only had 25 features. But today, Regex has
(lemme count) 8 anchors, 9 character classes, 8 assertions, 10 quantifiers,
9 backreferences, 10 range syntaxes, 7 pattern modifiers, 14 metacharacters,
passive/active, greedy/ungreedy concept, in total, roughly 75 symbols and
concepts to confuse one's head. Old dog programmers who have been with Regex
throughout its history might not be noticing this, but for newbies, who have
to memorize whole Regex machine in one fell swoop, is is already very hard
to learn. I think that with the number of features that Regex already has,
adding more causes disproportionate growth in learning overhead for newbies.
----------------------------------------
Feature #1873: MatchData#[]: Omits All But Last Captures Corresponding to the Same Named Group
https://bugs.ruby-lang.org/issues/1873#change-26829

Author: runpaint (Run Paint Run Run)
Status: Feedback
Priority: Normal
Assignee: naruse (Yui NARUSE)
Category: core
Target version: 2.0.0


=begin
 I suspect that MatchData#[:symbol] should return an Array of values when the same named group has been matched multiple times.
 
   >> m = 'food'.match(/(?<f>oo)(?<f>d)/)
   => #<MatchData "ood" f:"oo" f:"d">
   >> m[:f]
   => "d"
   >> m.to_a
   => ["ood", "oo", "d"]
=end



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