How do you extend a class externally?

ruby-talk
1

how do you extend a class externally?

module B
	...
end

class A
	...
end

# ???
A.include(B)
A.extend(B)
A.append_features(B)
A.class_eval { include B }

none of these work.

···

–
tom sawyer, aka transami
transami@transami.net

2

Tom Sawyer wrote:

how do you extend a class externally?

    module B
            ...
    end

    class A
            ...
    end

    # ???
    A.include(B)

A.instance_eval {include(B)}

appears to work.

But then again, there is no need to extend it externally in Ruby. You
can always reopen a class scope and do
class A; include B; end

···

–
([ Kent Dahl ]/)_ ~ [ http://www.stud.ntnu.no/~kentda/ ]/~
))_student/(( _d L b_/ NTNU - graduate engineering - 5. year )
( __õ|õ// ) )Industrial economics and technological management(
_/ö____/ (_engineering.discipline=Computer::Technology)

3

Tom Sawyer wrote:

how do you extend a class externally?

module B
…
end

class A
…
end

???

A.include(B)
A.extend(B)
A.append_features(B)
A.class_eval { include B }

none of these work.

class A
include B
end

…if I remember correctly.

HTH

Stephan

4

how do you extend a class externally?

module B
…
end

class A
…
end

???

A.include(B)
include is private
A.extend(B)
This works, but doesn’t do what you want as it is performed on singleton level.

A.append_features(B)
this is private too
A.class_eval { include B }
This works, AFAIK.
cpmf2196@l4 ~ $ ruby
class A
end
module B
def boo
p “BOO”
end
end
A.class_eval “include B”
A.new.boo
“BOO”

none of these work.

Is there a reason for Module (Class?, have no ri here)#include to be private?

···

On Fri, Jan 24, 2003 at 06:40:21PM +0900, Tom Sawyer wrote:

–
_ _

__ __ | | ___ _ __ ___ __ _ _ __
'_ \ / | __/ __| '_ _ \ / ` | ’ \
) | (| | |__ \ | | | | | (| | | | |
.__/ _,|_|/| || ||_,|| |_|
Running Debian GNU/Linux Sid (unstable)
batsman dot geo at yahoo dot com

#if _FP_W_TYPE_SIZE < 64
#error “Only stud muffins allowed, schmuck.”
#endif
– linux/arch/sparc64/quad.c

5

A.instance_eval {include(B)}
appears to work.

really

But then again, there is no need to extend it externally in Ruby. You
can always reopen a class scope and do
class A; include B; end

Doh! i knew that. what was i thinking? kind of odd that there’s no direct
method for it though.

anyhow, i implemented it and it greatly slowed down my app. oh well, although
i wanted better SOC i went back to including the modules into the original
classes.

···

On Friday 24 January 2003 02:48 am, Kent Dahl wrote:

–
tom sawyer, aka transami
transami@transami.net

6

A.extend(B)
This works, but doesn’t do what you want as it is performed on singleton
level.

A.append_features(B)

this is private too

A.class_eval { include B }

funny, my code was bombing on these. no matter though as they aren’t
preferable solutions anyway.

Is there a reason for Module (Class?, have no ri here)#include to be
private?

i would like to know this too. matz?

···

On Friday 24 January 2003 05:19 am, Mauricio Fernández wrote:

–
tom sawyer, aka transami
transami@transami.net