Blocks expected arguments and metaprogramming

Ruby
1

hi all,

in this (Parked at Loopia ) code :

module Kernel
def expected_argument_list
2
end

def before (name)
puts :hola
define_method(name){
if expected_argument_list==1
yield :only_one
else
yield :one,:two
end
}
end
end

class A
before :foo do |*args|
puts second
end

before :foo do |first , second|
puts second
end
end

a = A.new
a.foo

Does anyone know of a way to determine what argument list was
specified when the block is created?

i mean i want to implement the function expected_argument_list, to
return the length of the argument list that the block expected.
Probably is not possible to do that :frowning:

When are defined the variables of the block, in the class definition
time, or after the yield call?

Thanks

–

Pedro Del G.

Email : [email protected]

2

On Sep 16, 8:10 am, “Pedro Del G.” [email protected]
wrote:

hi all,

in this (Parked at Loopia) code :

module Kernel
def expected_argument_list
2
end

def before (name, &blk)
puts :hola
define_method(name){
if blk.arity==1
yield :only_one
else
yield :one,:two
end
}
end
end

It’s not quite as simple as that but that should be enough to move you
forward.

T.

3

end
end
end

It’s not quite as simple as that but that should be enough to move you
forward.

Yes thats enough for me. I didnt now that the block was a Proc class.

Thanks.

–

Pedro Del G.

Email : [email protected]

4

On 9/16/07, Pedro Del G. [email protected] wrote:

 puts :hola

class A
a.foo

The block arguments are only known at runtime, since you could do this:
def example
args = []
rand(15).times {|i| args << i}
yield *args
end

5

BTW, its works perfectly, with that i can decide what parameter return
in advances, (but, yet, I dont know is a good idea or not)

Thanks

module Kernel
def before (name, &block)
define_method(name) do
if block.arity == 1
yield :only_one
elsif block.arity == 2
yield :one,:two
elsif block.arity == -2
yield :one, :a , :splater, :argument
end
end
end
end

class A
before :foo do |first|
puts first
end
end

a = A.new
a.foo

class A
before :foo do |first , second|
puts second
end
end

a2 = A.new
a2.foo

class A
before :foo do |first , *splat_arg|
puts splat_arg
end
end

a3 = A.new
a3.foo

2007/9/16, Pedro Del G. [email protected]:

end
end
–

Pedro Del G.

Email : [email protected]

–

Pedro Del G.

Email : [email protected]