[ruby-core:89438] [Ruby trunk Feature#15231] Remove `Object#=~`

[ruby-core:89438] [Ruby trunk Feature#15231] Remove `Object#=~`

[mame]

Issue #15231 has been reported by mame (Yusuke Endoh).

----------------------------------------
Feature #15231: Remove `Object#=~`
https://bugs.ruby-lang.org/issues/15231

* Author: mame (Yusuke Endoh)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
`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 hided 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 said `NilClass#=~` should be newly introduced because of: `if gets =~ /re/`
* `Object#!~` is difficult to remove: some classes define only `#=~`, and expect `Object#!~` to delegate to `#=~`.



-- 
https://bugs.ruby-lang.org/

[ruby-core:89440] [Ruby trunk Feature#15231] Remove `Object#=~`

[naruse]

Issue #15231 has been updated by naruse (Yui NARUSE).


rubocop should alert `obj =~ re` to fix as `re =~ obj`.

----------------------------------------
Feature #15231: Remove `Object#=~`
https://bugs.ruby-lang.org/issues/15231#change-74478

* Author: mame (Yusuke Endoh)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
`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 hided 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 said `NilClass#=~` should be newly introduced because of: `if gets =~ /re/`
* `Object#!~` is difficult to remove: some classes define only `#=~`, and expect `Object#!~` to delegate to `#=~`.



-- 
https://bugs.ruby-lang.org/

[ruby-core:89455] [Ruby trunk Feature#15231] Remove `Object#=~`

[sawadatsuyoshi]

Issue #15231 has been updated by sawa (Tsuyoshi Sawada).


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:

```ruby
// =~ Object.new # >> TypeError: no implicit conversion of Object into String
"" =~ Object.new # => nil
```

----------------------------------------
Feature #15231: Remove `Object#=~`
https://bugs.ruby-lang.org/issues/15231#change-74495

* Author: mame (Yusuke Endoh)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
`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.

```RUBY
["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`:

```RUBY
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 said `NilClass#=~` should be newly introduced because of: `if gets =~ /re/`
* `Object#!~` is difficult to remove: some classes define only `#=~`, and expect `Object#!~` to delegate to `#=~`.



-- 
https://bugs.ruby-lang.org/

[ruby-core:89483] [Ruby trunk Feature#15231] Remove `Object#=~`

[zn]

Issue #15231 has been updated by znz (Kazuhiro NISHIYAMA).


```ruby
"" =~ "" #=> TypeError (type mismatch: String given)
```

----------------------------------------
Feature #15231: Remove `Object#=~`
https://bugs.ruby-lang.org/issues/15231#change-74524

* Author: mame (Yusuke Endoh)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
`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.

```RUBY
["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`:

```RUBY
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 said `NilClass#=~` should be newly introduced because of: `if gets =~ /re/`
* `Object#!~` is difficult to remove: some classes define only `#=~`, and expect `Object#!~` to delegate to `#=~`.



-- 
https://bugs.ruby-lang.org/

[ruby-core:89986] [Ruby trunk Feature#15231] Remove `Object#=~`

[matz]

Issue #15231 has been updated by matz (Yukihiro Matsumoto).


I vote for the proposed change. Let's give deprecation warning first. I don't think we need to remove `!~` from `Kernel`.

Matz.


----------------------------------------
Feature #15231: Remove `Object#=~`
https://bugs.ruby-lang.org/issues/15231#change-75091

* Author: mame (Yusuke Endoh)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
`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.

```RUBY
["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`:

```RUBY
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 said `NilClass#=~` should be newly introduced because of: `if gets =~ /re/`
* `Object#!~` is difficult to remove: some classes define only `#=~`, and expect `Object#!~` to delegate to `#=~`.



-- 
https://bugs.ruby-lang.org/