Get formal parameter names of a method?

Ruby
1

Is there a way to reflect on a method to get the declard names of the
parameters?

class Equipment

def install(tool, packaging)
end

end

I can do this:

m = Equipment.new.method(:install)
m.arity # => 2

I want to somehow find out that the client code has declared the
parameters named ‘tool’ and ‘packaging’.

Is this possible somehow? I feel like it should be, but I can’t quite
figure it out.

Thanks!
Jeff

2

On 8/14/06, Jeff C. [email protected] wrote:

Is there a way to reflect on a method to get the declard names of the
parameters?

Not in this version of Ruby. I don’t know if it’s planned.

-austin

3

Jeff C. wrote:

I can do this:

m = Equipment.new.method(:install)
m.arity # => 2

I want to somehow find out that the client code has declared the
parameters named ‘tool’ and ‘packaging’.

Is this possible somehow? I feel like it should be, but I can’t quite
figure it out.

It’s not possible without access to the source code or some major
interpreter patches.

Kind regards

robert
4

On 8/14/06, Jeff C. [email protected] wrote:

I can do this:
Thanks!
Jeff

the only way you could do this now would be to use ParseTree:

http://rubyforge.org/projects/parsetree/

Maybe there will be a built-in way to do this in 2.0?

Phil

5

Not that I know of but:
def install_args
[:tool,:packaging]
end

m = Equipment.new.method(:install)
Equipment.new.method(:install_args)
#m.arity # => 2

6

Phil T. wrote:

Phil
Its a long shot but as a nasty hack you could read the original source
file in and search to locate the “def” of the method and then via a
regex extract the names of the arguments. This would likely be very
slow so you’d probably want to do it once and for all for all methods
of interest. But, as a circular problem, how would you know the names
of the methods of interest in advance? Well, that would have to be an
assumption I suppose.

Good Luck,

Ken

7

In article [email protected],
Kenosis [email protected] wrote:

Is this possible somehow? I feel like it should be, but I can’t quite
Maybe there will be a built-in way to do this in 2.0?

Phil
Its a long shot but as a nasty hack you could read the original source
file in and search to locate the “def” of the method and then via a
regex extract the names of the arguments. This would likely be very
slow so you’d probably want to do it once and for all for all methods
of interest. But, as a circular problem, how would you know the names
of the methods of interest in advance? Well, that would have to be an
assumption I suppose.

If you’re going to do that you might as well use ParseTree.

Phil

8

On Aug 14, 2006, at 2:16 PM, Jeff C. wrote:

Is there a way to reflect on a method to get the declard names of the
parameters?
[…]
Is this possible somehow? I feel like it should be, but I can’t quite
figure it out.

What is the use case for this sort of thing? Off hand the only reason
I could see needing this would be for some sort of debugger/ide/
development
tool, in which case ParseTree might be a solution.

Gary W.