Issue #8579 has been updated by headius (Charles Nutter).


See also http://bugs.ruby-lang.org/issues/8992 which proposes just making "literal string".freeze do the right thing in the compiler.

FROZEN { } is not terrible syntax, but it's the longest one suggested.
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Feature #8579: Frozen string syntax
https://bugs.ruby-lang.org/issues/8579#change-42321

Author: charliesome (Charlie Somerville)
Status: Closed
Priority: Normal
Assignee: charliesome (Charlie Somerville)
Category: syntax
Target version: current: 2.1.0


I'd like to propose a new type of string literal - %f().

Because Ruby strings are mutable, every time a string literal is evaluated a new String object must be duped.

It's quite common to see code that stores a frozen String object into a constant which is then reused for performance reasons. Example: https://github.com/rack/rack/blob/master/lib/rack/methodoverride.rb

A new %f() string literal would instead evaluate to the same frozen String object every time. The benefit of this syntax is that it removes the need to pull string literals away from where they are used.

Here's an example of the proposed %f() syntax in action:

    def foo
      ["bar".object_id, %f(bar).object_id]
    end

    p foo # might print "[123, 456]"

    p foo # might print "[789, 456]"

These string literals could also be stored into a global refcounted table for deduplication across the entire program, futher reducing memory usage.

If this proposal is accepted, I can handle implementation work.


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