Feature #15231
closedRemove `Object#=~`
Description
Object#=~
receives (and just discards) an argument, and always returns nil. What purpose is this method for?
The following behavior that Object#=~
caused was confusing to me.
["foo"] =~ /foo/ #=> nil
More precisely: the actual example that I encountered was to parse coverage data from output of coverage measurement tool by using Open3.capture2
:
out = Open3.capture2("gcov", ...) # BUG: `out, =` was intended
if out =~ /lines\.*: *(\d+\.\d+)%/
...
end
Obviously, I forgot a comma to receive the return value of Open3.capture2
. The method returns a two-element array, and out =~
calls Object#=~
, which hid the bug. (Worse, I took several tens of minutes to debug it because I first thought that this is a bug of regexp, and spent tweaking the regexp.)
I guess Object#=~
was intended for general pattern matching, but presently the role was taken over by Object#===
.
So. How about removing Object#=~
?
Concerns:
- @usa (Usaku NAKAMURA) said
NilClass#=~
should be newly introduced because of:if gets =~ /re/
-
Object#!~
is difficult to remove: some classes define only#=~
, and expectObject#!~
to delegate to#=~
.
Updated by naruse (Yui NARUSE) about 6 years ago
rubocop should alert obj =~ re
to fix as re =~ obj
.
Updated by znz (Kazuhiro NISHIYAMA) about 6 years ago
- Description updated (diff)
Updated by sawa (Tsuyoshi Sawada) about 6 years ago
I agree. At the same time, the String=~
behaviour:
str =~ obj → integer or nil click to toggle source
Match—If obj is a Regexp, use it as a pattern to match against str,and returns the position the match starts, or nil if there is no match. Otherwise, invokes obj.=~, passing str as an argument. The default =~ in Object returns nil.
(from https://ruby-doc.org/core-2.4.0/String.html#method-i-3D~)
should be changed to raise a TypeError
when obj
is not a Regexp
, on a par with Regexp#=~
given a non-String
argument. Afterall, the following unnatural asymmetry in the current behaviour should be resolved:
// =~ Object.new # >> TypeError: no implicit conversion of Object into String
"" =~ Object.new # => nil
Updated by znz (Kazuhiro NISHIYAMA) about 6 years ago
"" =~ "" #=> TypeError (type mismatch: String given)
Updated by matz (Yukihiro Matsumoto) almost 6 years ago
I vote for the proposed change. Let's give deprecation warning first. I don't think we need to remove !~
from Kernel
.
Matz.
Updated by mame (Yusuke Endoh) almost 6 years ago
- Status changed from Open to Closed
Applied in changeset trunk|r65984.
lib/webrick: explicitly convert header values to a string
The values of @header are expected to be all strings;
WEBrick::HTTPResponse::[]=(key, val) explicitly converts the second
argument to a string and assigns it to @header hash.
However, there were some points in WEBrick internal code that assigns
non-String to @header. This change fixes the issues.
The values are checked by header_value =~ /\r\n/
in check_header.
The type confusion caused conflict with removal of Object#=~
[Feature #15231].