From: bughitgithub@...
Date: 2019-11-04T17:00:47+00:00
Subject: [ruby-core:95671] [Ruby master Feature#11660] a falsy value (similar to js undefined) that facilitates forwarding of default arguments

Issue #11660 has been updated by bughit (bug hit).


> The "penalty" I pay for this is one line of code

The penalty the language pays is it has a demoware, checklist item, default value feature, where in any non-trivial scenario you have to produce the default value twice, first the intermediate default value through the default value expression, then the real default value in the body. You are not doing ruby any favors by defending this "design".

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Feature #11660: a falsy value (similar to js undefined) that facilitates forwarding of default arguments
https://bugs.ruby-lang.org/issues/11660#change-82459

* Author: bughit (bug hit)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
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I'll call it "missing" here.  Consider the following scenario:

```ruby
def foo(default1 = some_expression)
end

def bar(default1 = some_expression)
  foo default1
end

def foobar(default1 = some_expression)
  bar default1
end 
```

if you had "missing":

```ruby
def foo(default1 = some_expression)
end

def bar(default1 = missing)
  foo default1
end

def foobar(default1 = missing)
  bar default1
end 
```
missing passed as arg would be ignored (as if it wasn't passed at all)
and you wouldn't have to repeat the default value expression in every method

I believe that's how undefined works in js6 with respect to default args 




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