From: shyouhei@...
Date: 2016-11-20T13:38:28+00:00
Subject: [ruby-core:78229] [Ruby trunk Feature#12957] A more OO way to	create lambda Procs

Issue #12957 has been updated by Shyouhei Urabe.


Problem is, when you allow LambdaProc.new, that have to accept non-lambda procs, like LambdaProc.new(&nonlambda).  This way, a proc would be converted from/between lambda and non-lambda.

This is not a good idea.  Right now a lambda is born to be a lambda and there is no way to turn it into a proc.  If such property breaks, a programmer cannot guarantee what to expect to a block they wrote's parameter, because that proc can later be changed into a lambda by someone else.  And there is no way to detect such change from that block itself before it is called.

----------------------------------------
Feature #12957: A more OO way to create lambda Procs
https://bugs.ruby-lang.org/issues/12957#change-61594

* Author: Colin Fulton
* Status: Open
* Priority: Normal
* Assignee: 
----------------------------------------
Currently to create a lambda Proc one has to use `lambda { }` or `-> { }`. For doing metaprogramming it would be nice to have a more OO way to generate them. Something like `LambdaProc.new`. That way one could write:

```ruby
class MetaThingy
  def initialize proc_class
    @anonymous_function = proc_class.new do
      # Some Code
    end
  end
end
```

and pass in either `Proc` or `LambdaProc` depending on their needs, instead of:

```ruby
class MetaThingy
  def initialize proc_type
    @anonymous_function = case proc_type
                          when :proc
                            proc do
                              # Some Code
                            end
                          when :lambda
                            lambda do
                              # Some Code
                            end
                          end
    end
  end
end
```

This is not a common use case, but would help make the language more orthogonal.



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