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I would like to be able to be able to include instance methods of a
Struct into a class. e.g.

foo = Struct.new(:attribute, :another_attribute)
bar = foo.new

class Bas

some_ruby_magic

end

So that I can then do

Bas.attribute="a value"
Bas.attribute

Kind of like doing module_functions but that doesn't work inside a
class.
Thanks,
James

On 11/11/06, J2M <> wrote:
> I would like to be able to be able to include instance methods of a
> Struct into a class. e.g.
>
> foo = Struct.new(:attribute, :another_attribute)
> bar = foo.new
>
> class Bas
>
> some_ruby_magic
>
> end
>
> So that I can then do
>
> Bas.attribute="a value"
> Bas.attribute
>
> Kind of like doing module_functions but that doesn't work inside a
> class.

class Bas
@__struct__ = Struct.new(:attribute, :another_attribute)

class << self
def method_missing(sym, *args)
@__struct__.send(sym, *args) if @__struct__.respond_to?(sym)
end
end
end

That should work.

-austin
--
Austin Ziegler * * http://www.halostatue.ca/
* * http://www.halostatue.ca/feed/
*

On Sun, 12 Nov 2006, J2M wrote:

> I would like to be able to be able to include instance methods of a
> Struct into a class. e.g.
>
> foo = Struct.new(:attribute, :another_attribute)
> bar = foo.new
>
> class Bas
>
> some_ruby_magic
>
> end
>
> So that I can then do
>
> Bas.attribute="a value"
> Bas.attribute
>
> Kind of like doing module_functions but that doesn't work inside a
> class.
> Thanks,
> James


harp:~ > cat a.rb
class Module
def struct_attrs struct
singleton_class = class << self
self
end
singleton_class.module_eval{ struct.members.each{|m| attr_accessor m} }
end
end

class Bas
foo = Struct.new :attribute, :another_attribute
bar = foo.new

struct_attrs foo
end

Bas.attribute = "a value"
p Bas.attribute


harp:~ > ruby a.rb
"a value"



-a
--
my religion is very simple. my religion is kindness. -- the dalai lama

J2M wrote:
> I would like to be able to be able to include instance methods of a
> Struct into a class. e.g.
>
> foo = Struct.new(:attribute, :another_attribute)
> bar = foo.new
>
> class Bas
>
> some_ruby_magic
>
> end
>
> So that I can then do
>
> Bas.attribute="a value"
> Bas.attribute
> Kind of like doing module_functions but that doesn't work inside a
> class.

Foo = Struct.new(:attribute, :another_attribute)

class Bas
extend Foo.to_module
end

Ha! Only if it were so easy! Actaully if one had access to Ruby's
source it would rather trivial (hint). In anycase to par down Ara's
solution to it's core:

Foo = Struct.new :attribute, :another_attribute

class Bas
class << self
attr_accessor *Foo.members
end
end

Note the use of the constant which eases access by avoiding
(class<<self;self;end).class_eval.

T.

J2M wrote:
> I would like to be able to be able to include instance methods of a
> Struct into a class. e.g.
>
> foo = Struct.new(:attribute, :another_attribute)
> bar = foo.new
>
> class Bas
>
> some_ruby_magic
>
> end
>
> So that I can then do
>
> Bas.attribute="a value"
> Bas.attribute
>
> Kind of like doing module_functions but that doesn't work inside a
> class.

I don't know why people make it so complicated. All these are easier
than other approaches suggested so far:

Foo = Struct.new(:attribute, :another_attribute)
class Bas < Foo
end

class Bas < Struct.new(:attribute, :another_attribute)
end

or even

Bas = Struct.new(:attribute, :another_attribute) do
def another_method() end
end

Kind regards

robert

Robert, T, A & Austin;

A plethora of choices. All while I slept too

Thank you all.
James

Hi--

On Sun, 12 Nov 2006, Robert Klemme wrote:

> J2M wrote:
>> I would like to be able to be able to include instance methods of a
>> Struct into a class. e.g.
>>
>> foo = Struct.new(:attribute, :another_attribute)
>> bar = foo.new
>>
>> class Bas
>>
>> some_ruby_magic
>>
>> end
>>
>> So that I can then do
>>
>> Bas.attribute="a value"
>> Bas.attribute
>>
>> Kind of like doing module_functions but that doesn't work inside a
>> class.
>
> I don't know why people make it so complicated. All these are easier than
> other approaches suggested so far:
>
> Foo = Struct.new(:attribute, :another_attribute)
> class Bas < Foo
> end
>
> class Bas < Struct.new(:attribute, :another_attribute)
> end
>
> or even
>
> Bas = Struct.new(:attribute, :another_attribute) do
> def another_method() end
> end

You're adding instance methods to Bas rather than to Bas's singleton
class, though. The OP wants to do:

Bas.attribute = "a value"


David

--
David A. Black |
Author of "Ruby for Rails" [1] | Ruby/Rails training & consultancy [3]
DABlog (DAB's Weblog) [2] | Co-director, Ruby Central, Inc. [4]
[1] http://www.manning.com/black | [3] http://www.rubypowerandlight.com
[2] http://dablog.rubypal.com | [4] http://www.rubycentral.org

wrote:
> Hi--
>
> On Sun, 12 Nov 2006, Robert Klemme wrote:
>
>> J2M wrote:
>>> I would like to be able to be able to include instance methods of a
>>> Struct into a class. e.g.
>>>
>>> foo = Struct.new(:attribute, :another_attribute)
>>> bar = foo.new
>>>
>>> class Bas
>>>
>>> some_ruby_magic
>>>
>>> end
>>>
>>> So that I can then do
>>>
>>> Bas.attribute="a value"
>>> Bas.attribute
>>>
>>> Kind of like doing module_functions but that doesn't work inside a
>>> class.
>>
>> I don't know why people make it so complicated. All these are
>> easier than other approaches suggested so far:
>>
>> Foo = Struct.new(:attribute, :another_attribute)
>> class Bas < Foo
>> end
>>
>> class Bas < Struct.new(:attribute, :another_attribute)
>> end
>>
>> or even
>>
>> Bas = Struct.new(:attribute, :another_attribute) do
>> def another_method() end
>> end
>
> You're adding instance methods to Bas rather than to Bas's singleton
> class, though. The OP wants to do:
>
> Bas.attribute = "a value"

Oh, ok then I misinterpreted that. I read "include instance methods
into a class" as including them as instance methods. My bad. Sorry for
the noise.

In this particular case, /if/ the aim is to define attribute accessors a
direct definition is probably the easiest solution

class Bas
class <<self
attr_accessor :attribute, :another_attribute
end
end

Regards

robert

I got the final solution down to this which I think is rather elegant;

class Bas < Struct.new :attribute, :another_attribute
class << self
attr_accessor *Bas.members
end
end

I love this languate; and now really appreciate the power of the
singleton class.

Thanks.

J2M wrote:
> I got the final solution down to this which I think is rather elegant;
>
> class Bas < Struct.new :attribute, :another_attribute
> class << self
> attr_accessor *Bas.members
> end
> end

class Bas < Struct.new :attribute, :another_attribute
class << self
attr_accessor *members
end
end

Do you realize that you are adding #attribute and #another_attribute at
both the instance level and the class level, and niether will reference
tha same values? I.e.

Bas.attribute = 1
bas = Bas.new
bas.attribute = 2
Bas.attribute #=> 1
bas.attribute #=> 2

T.