From: Alexandre Mutel <alexandre_mutel@...>
Date: 2009-12-01T23:53:49+09:00
Subject: Ruby should support consistent constant lookup (and dynamic)

Just a general remark about this problem. Shouldn't Ruby have a builtin 
mechanism to resolve dynamically and efficiently constants handling 
lexical scopes correctly?

Seems that in 1.9, we have this features:
irb(main):001:0> class A
irb(main):002:1>   BAR = 1
irb(main):003:1>   class B
irb(main):004:2>     def self.foo(&b)
irb(main):005:3>       instance_eval(&b)
irb(main):006:3>     end
irb(main):007:2>   end
irb(main):008:1> end
=> nil
irb(main):009:0> A::B.foo do
irb(main):010:1* puts BAR
irb(main):011:1> end
1
=> nil
irb(main):012:0>

BUT now, try to do it with const_get, and we got a NameError:
irb(main):012:0> A::B.foo do
irb(main):013:1* puts const_get(:BAR)
irb(main):014:1> end
NameError: uninitialized constant A::B::BAR
        from (irb):13:in `const_get'
        from (irb):13:in `block in irb_binding'
        from (irb):5:in `instance_eval'
        from (irb):5:in `foo'
        from (irb):12
        from E:/Code/Ruby/bin/irb:12:in `<main>'

This is quite frustrating when writing a DSL language to not being able 
to resolve constants dynamically (without getting a costly module 
hierarchy and checking the constant in each module...)

Should'nt this constant lookup be consistent between static and 
const_get?

-- 
Posted via http://www.ruby-forum.com/.