From: matthew@...
Date: 2014-08-08T22:09:59+00:00
Subject: [ruby-core:64275] [ruby-trunk - Feature #10095] Object#as

Issue #10095 has been updated by Matthew Kerwin.


 On 09/08/2014, rafaelmfranca@gmail.com <rafaelmfranca@gmail.com> wrote:
 > Issue #10095 has been updated by Rafael Fran��a.
 >
 >
 > I believe using `#itself` for this feature will cause confusion. By what I
 > could understand of the original proposal its idea is to return the result
 > of the block instead of the objects itself.
 >
 > The idea behind `#itself` is to return the object. If we add support to a
 > block and make the method return the result of the block we are just going
 > against the original idea of `#itself`.
 >
 
 I suppose examples will help illustrate what seems most clear. This is
 a short snippet along the lines of what I think makes this proposed
 method useful: a (long?) chain of methods that are prefixed/wrapped
 towards the end:
 
   n = gets.chomp.as{|i| Integer(i)}
   n = gets.chomp.itself{|i| Integer(i)}
 
   n = gets.chomp.as do |i|
     Integer(i)
   end
   n = gets.chomp.itself do |i|
     Integer(i)
   end
 
 In short short form #as seems appealing, but the long form it seems to
 me to be too messy. #itself never seems ambiguous to me, but then I'm
 already aware of #tap and can see that this is different.
 
 My preference is still for #itself
 
 
 
 Incidentally, I think #yield is a bad name because it does the exact
 opposite thing depending on whether you pass it a block:
 
   def foo &b
     yield {|o| ... }
     yield ...
   end
 
 
 -- 
   Matthew Kerwin
   http://matthew.kerwin.net.au/

----------------------------------------
Feature #10095: Object#as
https://bugs.ruby-lang.org/issues/10095#change-48262

* Author: Akira Matsuda
* Status: Open
* Priority: Normal
* Assignee: 
* Category: core
* Target version: current: 2.2.0
----------------------------------------
We've had so many times of feature requests for a method similar to Object#tap that doesn't return self but returns the given block's execution result (e.g. #7388, #6684, #6721 ).

I'm talking about something like this in Ruby of course:
Object.class_eval { def as() yield(self) end }

IIRC Matz is not against introducing this feature but he didn't like any of the names proposed in the past, such as embed, do, identity, ergo, reference, yield_self, itself, apply, map, tap!, etc.

So, let us propose a new name, Object#as today.
It's named from the aspect of the feature that it gives the receiver a new name "as" a block local variable.
For instance, the code reads so natural and intuitive like this:

(1 + 2 + 3 + 4).as {|x| x ** 2}
=> 100

Array.new.as {|a| a << 1; a << 2}
=> [1, 2]

---Files--------------------------------
itself-block.patch (1.35 KB)


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