From: danieldasilvaferreira@...
Date: 2018-01-10T11:15:45+00:00
Subject: [ruby-core:84808] [Ruby trunk Feature#14336] Create new method String#symbol? and deprecate Symbol class

Issue #14336 has been updated by dsferreira (Daniel Ferreira).


rosenfeld (Rodrigo Rosenfeld Rosas) wrote:

> Is it possible to generate a symbol from a string in SmallTalk, such as Ruby's 'string'.to_sym?

Symbol is a subclass of String in Smalltalk. See one of my previous comments.

> Since the hash issue is the one holding most of the confusion around the differences between symbols and strings, I'm focusing on it in order to try to minimize the impact of introducing incompatible changes and controlling its scope.

The hash issue is a consequence of the ecosystem.
We need to heal the ecosystem first.
Once properly healed issues like the hash one will be easily resolved.

The focus should be on the String vs Symbol relationship.
The transition path with minimal impact on current software.
Then next steps.
One step at a time.

----------------------------------------
Feature #14336: Create new method String#symbol? and deprecate Symbol class
https://bugs.ruby-lang.org/issues/14336#change-69522

* 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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