How to aliase a module method?

ruby-talk
1

I am trying to aliase a module method to some local alias (to ease some template). I've tried a few variations of

   alias escape_latex MyUtils.escape_latex

without luck so far. I could mixin the module or write a wrapper, but I'd like to know how to accomplish that with alias, or that it is not possible if that's the case.

-- fxn

2

I am trying to aliase a module method to some local alias (to ease
some template). I've tried a few variations of

   alias escape_latex MyUtils.escape_latex

without luck so far. I could mixin the module or write a wrapper, but
I'd like to know how to accomplish that with alias, or that it is not
possible if that's the case.

It's possible, sort of. Try

module TheModule
  instance_eval "alias escape_latex MyUtils.escape_latex"
end

I use a similar technique (originally suggested by Minero Aoki,
according to my notes) to replace Thread.critical and
Thread.critical=. I've only tested it in 1.8.2 but I don't think
anything's broken it since then.

···

On Mar 8, 5:34 am, Xavier Noria <f...@hashref.com> wrote:

-- fxn

3

first of all, you need to use symbols for methods (actually, you just
refer to the names of the methods):

alias :escape_latex :MyUtils.escape_latex

Can you see the problem: how you'd write the symbol for
MyUtils.escape_latex? This is not the way.
Now, this is excerpt from Ryan Davis' Ruby QuickRef
(http://www.zenspider.com/Languages/Ruby/QuickRef.html\):

Aliasing

alias :new :old
alias_method :new, :old

Creates a new reference to whatever old referred to. old can be any
existing method, operator, global. It may not be a local, instance,
constant, or class variable.

The simple solution would be in this case (provided you don't mind
including the other methods of the module):

include MyUtils

PS: I've tried

module TheModule
instance_eval "alias escape_latex MyUtils.escape_latex"
end

and I got:

(eval):1: parse error, unexpected '.', expecting $
alias escape_latex MyUtils.escape_latex
                           ^(pointing at the dot)

I don't think it'd work, but I may be wrong, and will be glad if somebody
will show the working code for this.

···

On 3/8/07, Xavier Noria <fxn@hashref.com> wrote:

I am trying to aliase a module method to some local alias (to ease
some template). I've tried a few variations of

   alias escape_latex MyUtils.escape_latex

without luck so far. I could mixin the module or write a wrapper, but
I'd like to know how to accomplish that with alias, or that it is not
possible if that's the case.

4

module M
   class << self
     alias_method 'dst', 'src'
   end
end

-a

···

On Fri, 9 Mar 2007 dseiler@etceteraedutainment.com wrote:

On Mar 8, 5:34 am, Xavier Noria <f...@hashref.com> wrote:

I am trying to aliase a module method to some local alias (to ease
some template). I've tried a few variations of

   alias escape_latex MyUtils.escape_latex

without luck so far. I could mixin the module or write a wrapper, but
I'd like to know how to accomplish that with alias, or that it is not
possible if that's the case.

It's possible, sort of. Try

module TheModule
instance_eval "alias escape_latex MyUtils.escape_latex"
end

I use a similar technique (originally suggested by Minero Aoki,
according to my notes) to replace Thread.critical and
Thread.critical=. I've only tested it in 1.8.2 but I don't think
anything's broken it since then.

-- fxn

--
be kind whenever possible... it is always possible.
- the dalai lama

5

No, that's not true.

-- fxn

···

On Mar 9, 2007, at 12:17 AM, Jan Svitok wrote:

first of all, you need to use symbols for methods (actually, you just
refer to the names of the methods):

6

I don't understand that technique (it is not working here). In fact what I don't understand is alias.

In irb we can do

   alias foo sprintf

Why can't we say

   alias foo Math.sqrt

? Having a quick glance at eval.c I think the problem is that alias is syntax (that's why it does not need a comma between its "arguments") and I guess here's the key:

   case NODE_ALIAS:
       if (NIL_P(ruby_class)) {
           rb_raise(rb_eTypeError, "no class to make alias");
       }
       rb_alias(ruby_class, rb_to_id(rb_eval(self, node->u1.node)),
                            rb_to_id(rb_eval(self, node->u2.node)));

-- fxn

···

On Mar 9, 2007, at 12:10 AM, dseiler@etceteraedutainment.com wrote:

On Mar 8, 5:34 am, Xavier Noria <f...@hashref.com> wrote:

I am trying to aliase a module method to some local alias (to ease
some template). I've tried a few variations of

   alias escape_latex MyUtils.escape_latex

without luck so far. I could mixin the module or write a wrapper, but
I'd like to know how to accomplish that with alias, or that it is not
possible if that's the case.

It's possible, sort of. Try

module TheModule
  instance_eval "alias escape_latex MyUtils.escape_latex"
end

I use a similar technique (originally suggested by Minero Aoki,
according to my notes) to replace Thread.critical and
Thread.critical=. I've only tested it in 1.8.2 but I don't think
anything's broken it since then.

7

Because alias requires that both arguments be names (or symbols), Note
that it's not a method but is directly performed by the ruby
interpreter.

irb(main):001:0> alias foo Math.sqrt
SyntaxError: compile error
(irb):1: parse error, unexpected '.', expecting $
alias foo Math.sqrt
               ^
        from (irb):1

You're not even getting to eval.c, it's failing to parse.

Module#alias_method requires that it's aruments be symbols
cooresponding to the name.

The other problem is that you are trying to make a name in a different
scope than the name you are aliasing. As far as I can see this isn't
possible.

···

On 3/8/07, Xavier Noria <fxn@hashref.com> wrote:

On Mar 9, 2007, at 12:10 AM, dseiler@etceteraedutainment.com wrote:

> On Mar 8, 5:34 am, Xavier Noria <f...@hashref.com> wrote:
>> I am trying to aliase a module method to some local alias (to ease
>> some template). I've tried a few variations of
>>
>> alias escape_latex MyUtils.escape_latex
>>
>> without luck so far. I could mixin the module or write a wrapper, but
>> I'd like to know how to accomplish that with alias, or that it is not
>> possible if that's the case.
>
> It's possible, sort of. Try
>
> module TheModule
> instance_eval "alias escape_latex MyUtils.escape_latex"
> end
>
> I use a similar technique (originally suggested by Minero Aoki,
> according to my notes) to replace Thread.critical and
> Thread.critical=. I've only tested it in 1.8.2 but I don't think
> anything's broken it since then.

I don't understand that technique (it is not working here). In fact
what I don't understand is alias.

In irb we can do

   alias foo sprintf

Why can't we say

   alias foo Math.sqrt

--
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/