From: "tadf (tadayoshi funaba)" <redmine@...>
Date: 2012-06-03T10:32:35+09:00
Subject: [ruby-core:45397] [ruby-trunk - Bug #6538][Closed] Mutability of Rational and Complex


Issue #6538 has been updated by tadf (tadayoshi funaba).

Status changed from Assigned to Closed

anyway forbade it.
this is not a magic.
but this trick seems also effective to others.

> r = Random.new
#=> #<Random:0xb87a6d50>
> a = r.marshal_dump
#=> [...]

> r.freeze
#=> #<Random:0xb87a6d50>
> r.frozen?
#=> true

> (0..10).map{r.rand}.to_a
#=> [0.31439277627295725, 0.22940914020883507, 0.1255127954343639, 0.22394641311330976, 0.5371394957199308, 0.6576211090277115, 0.7280552862872753, 0.4931093631805644, 0.6286785684826635, 0.6649446272706543, 0.32721416961292293]

> r.marshal_load(a)
#=> #<Random:0xb87a6d50>

> (0..10).map{r.rand}.to_a
#=> [0.31439277627295725, 0.22940914020883507, 0.1255127954343639, 0.22394641311330976, 0.5371394957199308, 0.6576211090277115, 0.7280552862872753, 0.4931093631805644, 0.6286785684826635, 0.6649446272706543, 0.32721416961292293]

----------------------------------------
Bug #6538: Mutability of Rational and Complex
https://bugs.ruby-lang.org/issues/6538#change-26982

Author: marcandre (Marc-Andre Lafortune)
Status: Closed
Priority: Low
Assignee: tadf (tadayoshi funaba)
Category: core
Target version: 
ruby -v: r35875


I hesitated to report this, but there is a "hole" in the immutability of Rational & Complex:

    r = Rational(0) # Rationals are immutable
    r.freeze        # but let's be certain and freeze it!
    magic_trick(r)  # r is now changed:
    r               # => (1/42)

The same thing occurs with Complex. I've left out the definition of `magic_trick` for anyone who wants to try and figure it out, but it's here: http://pastie.org/4016117

Is this worth fixing?



-- 
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