[ruby-core:109726] [Ruby master Feature#18408] Allow pattern match to set instance variables
From:
"Dan0042 (Daniel DeLorme)" <noreply@...>
Date:
2022-08-27 03:18:24 UTC
List:
ruby-core #109726
Issue #18408 has been updated by Dan0042 (Daniel DeLorme). @eregon I understand what you're saying, but my statement was based on the premise "if you don't want ivars to change during match". In the PR prepared by @palkan, ivars are modified as the match is evaluated, just like local vars, and the examples you provided would work. But ktsj and Matz said that it's not good for ivars to be modified as the match is evaluated, because that can "break the object status". Logically, it follows that the examples you provided would not work, or rather they would have to work with the value of `@v` before the matching starts. Because that's the entire point of "if you don't want ivars to change during match" (which btw I do not agree with). I have to admit I didn't think about guards. This opens a third possibility: a) ivars are assigned during match; examples above work as you assume; ktsj and Matz are opposed because of threads b) ivars are assigned after match and guard; examples above use value of `@v` prior to match c) ivars are assigned after match but before guard; examples with `[@v]` behave as you assume, example with `[@v,self]` behaves otherwise ---------------------------------------- Feature #18408: Allow pattern match to set instance variables https://bugs.ruby-lang.org/issues/18408#change-98961 * Author: Dan0042 (Daniel DeLorme) * Status: Rejected * Priority: Normal * Assignee: ktsj (Kazuki Tsujimoto) ---------------------------------------- I expected this to work: ```ruby 42 => @v ``` But instead it raises "syntax error, unexpected instance variable" Is this intentional? -- https://bugs.ruby-lang.org/ Unsubscribe: <mailto:ruby-core-request@ruby-lang.org?subject=unsubscribe> <http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>