From: merch-redmine@jeremyevans•net
To: ruby-dev@ruby-lang.org
Subject: [ruby-dev:50812] [Ruby master Feature#8853] Should String#sub(pattern) returns an Enumerator?
Date: Sat, 13 Jul 2019 00:32:36 +0000 (UTC) [thread overview]
Message-ID: <redmine.journal-79370.20190713003236.09bf8a16b4da1086@ruby-lang.org> (raw)
In-Reply-To: redmine.issue-8853.20130903100808@ruby-lang.org
Issue #8853 has been updated by jeremyevans0 (Jeremy Evans).
Backport deleted (1.9.3: UNKNOWN, 2.0.0: UNKNOWN)
ruby -v deleted (ruby 2.0.0p247 (2013-06-27 revision 41674) [x86_64-linux])
Tracker changed from Bug to Feature
File string-sub-enumerator.patch added
If I understand this correctly, this is a feature request to make `String#sub` and `#sub!` return an `Enumerator` if given a single argument and no block. I'm not sure how useful this would be. With `#sub!`, you can use the enumerator to mutate the string passing the replacement in via `Enumerator#feed`. However, with `#sub`, you cannot use the enumerator to modify anything, since the `String#sub` receiver is not modified, and you can't get access to the resulting string. However, assuming this is desired, the attached patch implements it.
----------------------------------------
Feature #8853: Should String#sub(pattern) returns an Enumerator?
https://bugs.ruby-lang.org/issues/8853#change-79370
* Author: okkez (okkez _)
* Status: Open
* Priority: Normal
* Assignee:
* Target version:
----------------------------------------
調べてみたのですが、過去に同様の議論があったのかどうかわからなかったので起票します。
以下のように String#sub(pattern) と使うと ArgumentError が発生します。
$ ruby -e "p ''.sub(//)"
-e:1:in `sub': wrong number of arguments (1 for 2) (ArgumentError)
from -e:1:in `<main>'
一方、 String#gsub(pattern) だと Enumerator を返します。
$ ruby -e "p ''.gsub(//)"
#<Enumerator: "":gsub(//)>
RDoc ではこの挙動は説明されていませんでした。
String#gsub(pattern)がEnumeratorを返すことについては書かれています。
http://www.ruby-doc.org/core-2.0.0/String.html#method-i-sub
http://www.ruby-doc.org/core-2.0.0/String.html#method-i-gsub
一貫性の観点から考えると、String#sub(pattern)もEnumeratorを返した方が良いように思いましたがいかがでしょうか。
まあ、String#sub だと置換は一回しか発生しないのでイマイチな感じはします。
* String#sub(pattern) が Enumerator を返すようになる
* RDoc に String#gsub(pattern) と違って String#sub(pattern) が ArgumentError を発生させることの記述が追加される
のどちらかが、満たされればいいと思っています。
---Files--------------------------------
string-sub-enumerator.patch (3.52 KB)
--
https://bugs.ruby-lang.org/
prev parent reply other threads:[~2019-07-13 0:32 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-03 1:08 [ruby-dev:47688] [ruby-trunk - Bug #8853][Open] Should String#sub(pattern) returns an Enumerator? okkez (okkez _)
2019-07-13 0:32 ` merch-redmine [this message]
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