Bending ruby space

Ruby
1

i came upon this “pattern” working on a rather difficult problem. see
if you can wrap your head around this bending of ruby space and what it
might be good for.

module R; end
module U; include R; end
module R; extend U; end

t.

2

Trans wrote:

i came upon this “pattern” working on a rather difficult problem. see
if you can wrap your head around this bending of ruby space and what it
might be good for.

module R; end
module U; include R; end
module R; extend U; end
why not:
module R; extend self end
or just:
module R; module_function; … end
?

Devin
(Thas right, biatches. extend self is the new class << self.)

3

Hi –

On Sun, 10 Dec 2006, Devin M. wrote:

or just:
module R; module_function; … end
?

Devin
(Thas right, biatches. extend self is the new class << self.)

I’m not sure what you mean. extend self doesn’t do what class << self
does. Am I misunderstanding?

David

4

On Dec 9, 2:51 pm, “Trans” [email protected] wrote:

see
if you can wrap your head around this bending of ruby space and what it
might be good for.

module R; end
module U; include R; end
module R; extend U; end

Job security? :wink:

5

[email protected] wrote:

I’m not sure what you mean. extend self doesn’t do what class << self
does. Am I misunderstanding?
It was a “green is the new blue” parody. Not a funny one, mind you, but
the use of “biatches” should’ve warned you of that.

Devin

6

On Sun, 10 Dec 2006, Trans wrote:

i came upon this “pattern” working on a rather difficult problem. see
if you can wrap your head around this bending of ruby space and what it
might be good for.

module R; end
module U; include R; end
module R; extend U; end

one side effect is that all instance methods of R are available at the
module
level too. i generally do that this way:

harp:~ > cat a.rb
class Module
def export meth
module_function meth
public meth
end
end

module R
def foo() 42 end
export :foo
end

p R.foo

harp:~ > ruby a.rb
42

what that what you were after, but wholesale?

interesting trick.

regards.

-a

7

John W. wrote:

On Dec 9, 2:51 pm, “Trans” [email protected] wrote:

see
if you can wrap your head around this bending of ruby space and what it
might be good for.

module R; end
module U; include R; end
module R; extend U; end

Job security? :wink:

LOL! :smiley:

Okay. When my headache goes away I’ll tell you too how you can secure
your job :wink:

T.

        .---------.

david | the box | me →
black most people
‘---------’

8

[email protected] wrote:

one side effect is that all instance methods of R are available at the module
module R
def foo() 42 end
export :foo
end

that’s an interesting method in it’s own right. i’m tempted to add to
facets, though maybe the name isn’t the best. I say that only b/c I’ve
been using #import to load a lib directly into the current module
space. and it would seem to me #import and #export should have some
related usage --one way or the other.

in any case you all are partly right of course. but the neat part of
this --the real “bending” and the reason it uses two modules the way
it does…

module R; end
module U; include R; end
module R; extend U; end

module R
def x; “x”; end
end

module U
def x; “{” + super + “}”; end
end

R.x #=> “{x}”

the effect is dynamic AOP wrapping of R by U. it is dynamic b/c it is
possible to define the “aspect” U prior to any corresponding method in
R. (btw, ‘if defined?(super)’ is helpful in such cases). I used this
myself to cache specifically named methods that may, or may not, be in
a user-defined code snippet.
it is unfortuate however that, afaict, the same pattern can’t be used
on a class --just a module.

t.

9

On Mon, 11 Dec 2006, Trans wrote:

end
myself to cache specifically named methods that may, or may not, be in
a user-defined code snippet.
it is unfortuate however that, afaict, the same pattern can’t be used
on a class --just a module.

dynamically injectable ‘super’ - very useful.

cheers.

-a

10

On Tue, 12 Dec 2006, Trans wrote:

include X
extend X
end

but that doesn’t work b/c

Q.f #=> ERROR: private method `f’ called for Q:Module

t.

 harp:~ > cat a.rb
 module X
   module_function  # side effect -> instance 'f' made private
   def f; "f"; end
   public :f
 # ^^^^^^ ^^
 # ^^^^^^ ^^
 # ^^^^^^ ^^
 end

 module Q
   module_function
   include X
   extend X
 end

 p Q.f

 p Object.new.instance_eval{ extend Q and self }.f

 include Q
 p f


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

regards.

-a

11

[email protected] wrote:

one side effect is that all instance methods of R are available at the module
module R
def foo() 42 end
export :foo
end

p R.foo

harp:~ > ruby a.rb
42

speaking of this “export” method, how does one do that for a whole
module? ie. adding one module_finction module to another.

module X
module_function
def f; “f”; end
end

module Q
module_function
include X
extend X
end

but that doesn’t work b/c

Q.f #=> ERROR: private method `f’ called for Q:Module

t.

12

On Tue, 12 Dec 2006, Trans wrote:

 end

but that undoes the module_function-ality of X.

??

harp:~ > cat a.rb
module X
module_function # side effect -> instance ‘f’ made private
def f; “f”; end
public :f
end

p X.f

include X
p self.f

harp:~ > ruby a.rb
“f”
“f”

-a

13

[email protected] wrote:

 harp:~ > cat a.rb
 module X
   module_function  # side effect -> instance 'f' made private
   def f; "f"; end
   public :f
 # ^^^^^^ ^^
 # ^^^^^^ ^^
 # ^^^^^^ ^^
 end

but that undoes the module_function-ality of X.

t.

14

[email protected] wrote:

 # ^^^^^^ ^^

def f; “f”; end
public :f
end

Exactly. Here let me give an actual example to help explain:

module CompressUtils
module_function
def tar_gz( folder, to_file=nil )
# …
end
end

I need CompressUtils to stay as is so as to work on it’s own as a
function module. But in one case I was thinking of doing:

module FileUtils
include_extend_or_whatever CompressUtils
end

With the desired effect being is as if I had originially done:

module FileUtils
module_function
def tar_gz( folder, to_file=nil )
# …
end
end

t.

15

[email protected] wrote:

module_function
harp:~ > cat a.rb
include Methods
end
include FileUtils
tar_gz ‘/’, ‘a.tgz’
self.class.tar_gz ‘/’, ‘a.tgz’

harp:~ > ruby a.rb
["/", “a.tgz”]
["/", “a.tgz”]
["/", “a.tgz”]

ah. yes i know this pattern. though i prefer #class_extension myself.
still not quite what i’m after but your sample helped jog my brain in
the right direction --thanks. i think this does it:

module CompressUtils
module_function
…
end

module FileUtils
include CompressUtils
module_function *(CompressUtils.private_instance_methods &
CompressUtils.methods(false))
end

that seem about right?

t.

16

On Tue, 12 Dec 2006, Trans wrote:

function module. But in one case I was thinking of doing:
# …
end
end

t.

ah. i use this alot, it’s concise and extremely powerful:

harp:~ > cat a.rb
module CompressUtils
module Methods
def tar_gz folder, to_file=nil
p [ folder, to_file ]
end
end
module ClassMethods
include Methods
end
module InstanceMethods
include Methods
end
def self.included other
other.module_eval{
include InstanceMethods if defined? InstanceMethods
extend ClassMethods if defined? ClassMethods
def self.included other
other.module_eval{
include InstanceMethods if defined? InstanceMethods
extend ClassMethods if defined? ClassMethods
}
end
}
end
end

module FileUtils
include CompressUtils
end

FileUtils.tar_gz ‘/’, ‘a.tgz’

include FileUtils
tar_gz ‘/’, ‘a.tgz’
self.class.tar_gz ‘/’, ‘a.tgz’

harp:~ > ruby a.rb
["/", “a.tgz”]
["/", “a.tgz”]
["/", “a.tgz”]

-a