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Bug #16448
closed
regex global variables are working differently depending on scope
Bug #16448: regex global variables are working differently depending on scope
Status:
Closed
Assignee:
-
Target version:
-
ruby -v:
ruby 2.6.5p114 (2019-10-01 revision 67812) [x86_64-darwin18]
Backport:
Tags:
Description
Hi, everyone.
I am trying to write a code similar to this
#!/usr/bin/env ruby def check(f1) f2 = ->(match) { p match; p $~ } data = "hello test test test" data.gsub(/test/, &f1) data.gsub(/test/, &f2) end check(->(match) { p match; p $~ }) output:
"test" nil "test" nil "test" nil "test" #<MatchData "test"> "test" #<MatchData "test"> "test" #<MatchData "test"> ruby versions:
ruby 2.6.5p114 (2019-10-01 revision 67812) [x86_64-darwin18]
ruby 2.3.0p0 (2015-12-25 revision 53290) [x86_64-darwin18]
Why does the global variable ($~) in f1 and f2 work differently? It's a bug or my mistake?
Updated by mame (Yusuke Endoh) almost 6 years ago
$~ is not a global variable, but a kind of local variable. String#gsub assigns the match data to $~ of its caller. data.gsub(/test/, &f1) assigns $~ of the scope of check. The lambda f1 reads $~ of the toplevel scope, which is not set.
You can see the behavior by the following code:
def check(f1) data = "foobar" data.gsub(/foo/, &f1) #=> #<MatchData "DUMMY"> p $~ #=> #<MatchData "foo"> f2 = ->(match) { p $~ } data.gsub(/bar/, &f2) #=> #<MatchData "bar"> p $~ #=> #<MatchData "bar"> end "DUMMY" =~ /DUMMY/ check(->(match) { p $~ }) 
Updated by tdrive (Stanislav Boldaev) almost 6 years ago
It is very unexpected.(
Thank you.
Updated by sawa (Tsuyoshi Sawada) almost 6 years ago
- Subject changed from regex global variables are working differently depend on scope to regex global variables are working differently depending on scope
- Description updated (diff)
Updated by jeremyevans0 (Jeremy Evans) almost 6 years ago
- Related to Bug #8444: Regexp vars $~ and friends are not thread local added
Updated by jeremyevans0 (Jeremy Evans) over 4 years ago
- Status changed from Open to Closed
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