From: "mame (Yusuke Endoh) via ruby-core" <ruby-core@ml.ruby-lang.org>
To: ruby-core@ml.ruby-lang.org
Cc: "mame (Yusuke Endoh)" <noreply@ruby-lang.org>
Subject: [ruby-core:120369] [Ruby master Bug#20965] `it` vs `binding.local_variables`
Date: Mon, 23 Dec 2024 03:37:39 +0000 (UTC) [thread overview]
Message-ID: <redmine.journal-111145.20241223033739.710@ruby-lang.org> (raw)
In-Reply-To: <redmine.issue-20965.20241218195830.710@ruby-lang.org>
Issue #20965 has been updated by mame (Yusuke Endoh).
Status changed from Closed to Open
Let's revert this change.
Below is our local discussion of this issue with @nobu and @ko1.
First, consider the following example.
```ruby
"foo".tap do
it
"bar".tap do
p eval("it") # what should happen?
end
end
```
There are three possible options.
1. Raises an exeption
2. Returns `"bar"`
3. Returns `"foo"`
1 is the only realistic choice. 2 would require keeping all arguments conservatively even when `it` does not appear lexically, which we want to avoid for a performance reason (including the possibility of future optimizations, as @ko1 said). 3 is clearly counterintuitive.
Then, consider the following example.
```ruby
"foo".tap do
it
"bar".tap do
p binding.local_variables #=> []? [:it]?
eval("it")
end
end
```
If `local_variables` contains `:it`, `eval("it")` is expected to return some value. However, it is impossible for the reason above. Therefore, `local_variables` should return `[]`.
The difference between `_1` and `it` is that `_1` is prohibited to be referenced outside of a block, while `it` is not.
Note that if `it` is defined as an ordinary local variable by an assignment, `local_variables` should contain `:it`.
----------------------------------------
Bug #20965: `it` vs `binding.local_variables`
https://bugs.ruby-lang.org/issues/20965#change-111145
* Author: zverok (Victor Shepelev)
* Status: Open
* ruby -v: ruby 3.4.0dev (2024-12-15T13:36:38Z master 366fd9642f) +PRISM [x86_64-linux]
* Backport: 3.1: DONTNEED, 3.2: DONTNEED, 3.3: DONTNEED
----------------------------------------
`it` is not available in the list of `binding.local_varaibles`, **unlike** numbered parameters:
```ruby
p(proc { binding.local_variables }.call) # []
p(proc { |x| binding.local_variables }.call) # [:x]
p(proc { _1; binding.local_variables }.call) # [:_1]
p(proc { vars = binding.local_variables; _1; vars }.call) # [:_1, :vars]
p(proc { it; binding.local_variables }.call) # []
```
I wonder if it is deliberate or accidental.
--
https://bugs.ruby-lang.org/
______________________________________________
ruby-core mailing list -- ruby-core@ml.ruby-lang.org
To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/
next prev parent reply other threads:[~2024-12-23 3:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-12-18 19:58 [ruby-core:120303] " zverok (Victor Shepelev) via ruby-core
2024-12-19 0:41 ` [ruby-core:120308] " shan (Shannon Skipper) via ruby-core
2024-12-19 6:28 ` [ruby-core:120317] " nobu (Nobuyoshi Nakada) via ruby-core
2024-12-19 9:33 ` [ruby-core:120326] " tompng (tomoya ishida) via ruby-core
2024-12-23 3:37 ` mame (Yusuke Endoh) via ruby-core [this message]
2024-12-23 4:55 ` [ruby-core:120372] " k0kubun (Takashi Kokubun) via ruby-core
2024-12-23 6:19 ` [ruby-core:120374] " zverok (Victor Shepelev) via ruby-core
2024-12-23 8:52 ` [ruby-core:120375] " mame (Yusuke Endoh) via ruby-core
2025-01-09 12:03 ` [ruby-core:120574] " mame (Yusuke Endoh) via ruby-core
2025-01-20 9:47 ` [ruby-core:120744] " mame (Yusuke Endoh) via ruby-core
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=redmine.journal-111145.20241223033739.710@ruby-lang.org \
--to=ruby-core@ml.ruby-lang.org \
--cc=noreply@ruby-lang.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).