Why does this include fail in instance_exec?

ruby-talk
1

The following code will dynamically create a class, C, inside of module
A. Class C would like to include module B which is also defined in
module A but the 'include B' line for C fails with `module_eval':
uninitialized constant Class::B (NameError).

I've included a class D definition as well which obviously works.

    module A
    end

    def create_class(c, &b)
        klass = A.const_set(c.capitalize, Class.new)
        klass.instance_exec(&b)
    end
    A.module_eval <<-EOF
        module B
            def self.append_features(m)
                puts "B"
            end
        end
        class D
            include B
        end
        create_class :c do
            include B
        end
    EOF

Any insight would be greatly appreciated.

Thanks,
Charlton

···

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2

I found a post that address this. I guess the nature of
instance_exec/eval has changed with respect to bindings.

http://coderrr.wordpress.com/2009/06/02/fixing-constant-lookup-in-dsls-in-ruby-1-9/

Charlton Wang wrote:

···

The following code will dynamically create a class, C, inside of module
A. Class C would like to include module B which is also defined in
module A but the 'include B' line for C fails with `module_eval':
uninitialized constant Class::B (NameError).

I've included a class D definition as well which obviously works.

    module A
    end

    def create_class(c, &b)
        klass = A.const_set(c.capitalize, Class.new)
        klass.instance_exec(&b)
    end
    A.module_eval <<-EOF
        module B
            def self.append_features(m)
                puts "B"
            end
        end
        class D
            include B
        end
        create_class :c do
            include B
        end
    EOF

Any insight would be greatly appreciated.

Thanks,
Charlton

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