Issue #15880 has been updated by duerst (Martin D=FCrst).


It's clear that the order of evaluation has to be the way it is currently. =
But in this case, `if` just sounds wrong, not only because of examples such=
 as `puts 1 if condition`, but also because of general English.

So I think changing `if` to something else is highly desirable. But I unfor=
tunately don't have any good proposal.

----------------------------------------
Bug #15880: Wrong precedence of the if modifier in pattern matching
https://bugs.ruby-lang.org/issues/15880#change-78250

* Author: ibylich (Ilya Bylich)
* Status: Rejected
* Priority: Normal
* Assignee: =

* Target version: =

* ruby -v: ruby 2.7.0dev (2019-05-20 trunk ab0f2deab1) [x86_64-darwin18]
* Backport: 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
When "If" is used as an "If modifier" it runs before the expression that it=
 wraps:
``` ruby
=3D> puts 1 if (puts 2; true)
2
1
```

However, when it's used in the pattern matching destructuring runs first:
``` ruby
class A
  def deconstruct
    puts 'deconstruct called'
    [1]
  end
end

p case A.new
in A[1] if (puts 'if check'; true)
  'yes'
else
  'no'
end

# prints
# deconstruct called
# if check
# "yes"
```

I personally think that it's very confusing as it doesn't reflect the code.=
 I assumed it to not run destructuring if the check returns `false` (especi=
ally because destructuring is allowed to have side-effects)



-- =

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