Issue #8579 has been updated by nobu (Nobuyoshi Nakada).


charliesome (Charlie Somerville) wrote:
> Also, if we used a modifier, how would that affect other types of percent literals like %w or %i?

As for %i, it doesn't make sense to freeze symbols, so it would freeze result array if it were introduced.
And all modifiers don't have to be applied to all kinds of literals.
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Feature #8579: Frozen string syntax
https://bugs.ruby-lang.org/issues/8579#change-40229

Author: charliesome (Charlie Somerville)
Status: Open
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
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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