From: merch-redmine@...
Date: 2018-01-23T15:41:21+00:00
Subject: [ruby-core:85008] [Ruby trunk Feature#14336] Create new method String#symbol? and deprecate Symbol class

Issue #14336 has been updated by jeremyevans0 (Jeremy Evans).


dsferreira (Daniel Ferreira) wrote:
> I believe it would be great to have:
> 
> ```ruby
> instance_variable_set(:foo, 1)
> instance_variable_get(:foo) # => 1
> @foo # => 1
> ```

The reason this doesn't work is by design.  You can actually store instance variables that don't start with @ using the C-API (rb_ivar_set), these are hidden from ruby land.  You will occasionally see this used in C extensions, and it is also used in core ruby (transcode.c, vm.c, enum.c).

In any case, this is unrelated to this feature request.  This feature request has already been rejected, so there is little reason to continue discussion. If an alternative proposal is put forth as a new feature request, it can be discussed there.

----------------------------------------
Feature #14336: Create new method String#symbol? and deprecate Symbol class
https://bugs.ruby-lang.org/issues/14336#change-69716

* Author: dsferreira (Daniel Ferreira)
* Status: Rejected
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
From  the discussions on the three previous issues related to the String vs Symbol subject ([5964](https://bugs.ruby-lang.org/issues/5964), [7792](https://bugs.ruby-lang.org/issues/7792), [14277](https://bugs.ruby-lang.org/issues/14277)) there are some conclusions we can assume:
* Current String vs Symbol is not the ideal scenario. See: Matz and Koichi comments.
* Current philosophy is to use Symbols as identifiers and Strings when strings are needed.
* Current situation is that Symbols are being used in many code bases as strings except for strings that really need the String methods.
* Current situation is that we are designing APIs to handle both String and Symbol inputs forcing an overhead of API development.

I propose the deprecation of `Symbol` class and the introduction of `String#symbol?`.

```ruby
foo = :foo
foo.class # => String
foo.symbol? # => true
bar = "bar"
bar.class # => String
bar.symbol? # => false
```

For backwards compatibility transition path I propose:

```ruby
class Symbol
  def self.===(var)
    warn ("Warning message regarding deprecated class")
    if var.class == Symbol
      true
    elsif var.class == String && var.symbol?
      true
    else
      false
    end
  end
end

class String
  def is_a?(klass)
    case klass
    when String
      true
    when Symbol
      self.symbol?
    else
      false
    end
  end
end
```



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