From: merch-redmine@jeremyevans.net
To: ruby-core@ruby-lang.org
Subject: [ruby-core:99207] [Ruby master Bug#17034] Unexpected behavior in #max for beginless range
Date: Fri, 17 Jul 2020 17:48:41 +0000 (UTC) [thread overview]
Message-ID: <redmine.journal-86585.20200717174841.2856@ruby-lang.org> (raw)
In-Reply-To: redmine.issue-17034.20200717040020.2856@ruby-lang.org
Issue #17034 has been updated by jeremyevans0 (Jeremy Evans).
citizen428 (Michael Kohl) wrote:
> I think this is not ideal. Possible solutions:
>
> 1. Return `e` (`RANGE_END(range)` for beginless ranges or
> 2. return a `RangeError` with a message like "cannot get the maximum of beginless range" (similar to `.min`).
>
>
> Happy to provide a patch if people want this changed and can agree on what the new behavior should be.
I think a `RangeError` is more correct. Without having a beginning, you cannot know the increment value, and therefore cannot know the maximum value. People that want the end of the range should use `Range#end`, not `Range#max`. However, I can see where `Range#max` returning the end for an inclusive beginless range could potentially be more useful.
----------------------------------------
Bug #17034: Unexpected behavior in #max for beginless range
https://bugs.ruby-lang.org/issues/17034#change-86585
* Author: citizen428 (Michael Kohl)
* Status: Open
* Priority: Normal
* ruby -v: 2.7.1p83 (2020-03-31 revision a0c7c23c9c) [x86_64-darwin19]
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN
----------------------------------------
When calling `max` on a beginless range, a non-intuitive error gets raised:
``` ruby
r = ..9
r.max
# ArgumentError: comparison of NilClass with 9 failed
```
There's a check for `NIL_P(RANGE_BEG(range))` but it's inside another check which is false for the example case above:
``` ruby
if (rb_block_given_p() || (EXCL(range) && !nm) || argc) {
if (NIL_P(RANGE_BEG(range))) {
rb_raise(rb_eRangeError, "cannot get the maximum of beginless range with custom comparison method");
}
return rb_call_super(argc, argv);
}
```
The first part of the condition is false since there is no block, and even though I'm not sure what `EXCL` does the second part of the condition will be false due to `!nm` (`nm` will be true because of `FIXNUM_P(e)`). So I think the error gets raised here:
``` ruby
int c = OPTIMIZED_CMP(b, e, cmp_opt);
```
I think this is not ideal. Possible solutions:
1. Return `e` (`RANGE_END(range)` for beginless ranges or
2. return a `RangeError` with a message like "cannot get the maximum of beginless range" (similar to `.min`).
Happy to provide a patch if people want this changed and can agree on what the new behavior should be.
---Files--------------------------------
range-max-beginless.patch (1.26 KB)
--
https://bugs.ruby-lang.org/
next prev parent reply other threads:[~2020-07-17 17:48 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-17 4:00 [ruby-core:99198] [Ruby master Bug#17034] Unexpected behavior in #max for beginless range citizen428
2020-07-17 16:26 ` [ruby-core:99206] " citizen428
2020-07-17 17:48 ` merch-redmine [this message]
2020-07-18 0:59 ` [ruby-core:99210] " citizen428
2020-07-18 16:12 ` [ruby-core:99214] " nobu
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-list from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.ruby-lang.org/en/community/mailing-lists/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=redmine.journal-86585.20200717174841.2856@ruby-lang.org \
--to=ruby-core@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 read-only IMAP folder(s) and NNTP newsgroup(s).