How to pass a function as parameter?

[Fritz Trapper]

I want to pass a reference to function as parameter to another function
and execute the passed function. Somthing like this:

def executer(func)
func(1)
end

def test(x)
p x
end

executer(test)

How to write this correctly in ruby?

 

[Marvin Gülker]

I want to pass a reference to function as parameter to another function
and execute the passed function. Somthing like this:

def executer(func)
func(1)
end

def test(x)
p x
end

executer(test)

How to write this correctly in ruby?

Are you looking for the #method method?
----------------------------------------
irb(main):001:0> def a
irb(main):002:1> puts "hello"
irb(main):003:1> end
=> nil
irb(main):004:0> def b(f)
irb(main):005:1> f.call
irb(main):006:1> end
=> nil
irb(main):007:0> m = methoda)
=> #<Method: Object#a>
irb(main):008:0> b(m)
hello
=> nil
irb(main):009:0>

 

[Jesús Gabriel y Galán]

I want to pass a reference to function as parameter to another function
and execute the passed function. Somthing like this:

def executer(func)
=A0 func(1)
end

def test(x)
=A0 p x
end

executer(test)

How to write this correctly in ruby?

A typical way would be using blocks or procs:

def executer
yield 1
end

executer {|x| puts "I got #{x}"}

If you want something to handle around in a variable:

func =3D lambda {|x| puts "I got #{x}"}
executer(&func) # =3D> I got 1

Or if in the executer you want to store the block for later use:

def executer(&block)
@save_for_later =3D block
end

#later...
@save_for_later.call(1) #or @save_for_later[1]

Hope this helps,

Jesus.

 

[Jeff Peng]

Jesús Gabriel y Galán:

A typical way would be using blocks or procs:

def executer
yield 1
end

executer {|x| puts "I got #{x}"}

If you want something to handle around in a variable:

func = lambda {|x| puts "I got #{x}"}
executer(&func) # => I got 1

for &func, what's the "&" before "func" here?

Thanks.

 

[Fritz Trapper]

Thanks for your quick replies.

I see, my scenario is somewhat more complicated, than I wrote in my
initial posting. The point is, that I want to pass an object and a
method.

Something like this:

def executer(obj, method)
f.method(1)
end

class x
def test(x)
p x
end
end

o = x.new
executer(o, test)

 

[Fritz Trapper]

Correction:

def executer(obj, method)
f.method(1)
end

Should be:
def executer(obj, method)
obj.method(1)
end

 

[Marnen Laibow-Koser]

Thanks for your quick replies.

I see, my scenario is somewhat more complicated, than I wrote in my
initial posting. The point is, that I want to pass an object and a
method.

Something like this:

def executer(obj, method)
f.method(1)
end

class x
def test(x)
p x
end
end

o = x.new
executer(o, test)

Why not just use o.sendtest) ?

Best,

 

[Fritz Trapper]

Why not just use o.sendtest) ?

Thanks, that helps.

 

[Jesús Gabriel y Galán]

Jes=FAs Gabriel y Gal=E1n:

for &func, what's the "&" before "func" here?

A method can receive regular parameters and a "special" block
parameter. The & lets you pass a proc as that special block parameter,
instead of a regular one:

irb(main):033:0> executer(func)
ArgumentError: wrong number of arguments (1 for 0)
from (irb):33:in `executer'
from (irb):33
from =03:0

Jesus.

 

[Jesús Gabriel y Galán]

Correction:

Should be:
def executer(obj, method)
=A0 obj.method(1)

obj.send(method, 1)

end

executer(O.new, :the_method)

Jesus.

 

[Josh Cheek]

[Note: parts of this message were removed to make it a legal post.]

Thanks for your quick replies.

I see, my scenario is somewhat more complicated, than I wrote in my
initial posting. The point is, that I want to pass an object and a
method.

Something like this:

def executer(obj, method)
f.method(1)
end

class x
def test(x)
p x
end
end

o = x.new
executer(o, test)

def executer(obj, method)
obj.send method , 1
end

class X
def test(x)
p x
end
end

o = X.new
executer( o , :test )

 

[Fritz Trapper]

Thanks for your help. I got it and it works fine.

Another question:
Is there some ruby reference on the web, something like
http://api.rubyonrails.org/ for example?

 

[Jesús Gabriel y Galán]

Thanks for your help. I got it and it works fine.

Another question:
Is there some ruby reference on the web, something like
http://api.rubyonrails.org/ for example?

http://ruby-doc.org/


Jesus.

 

[Fritz Trapper]

http://ruby-doc.org/

Thanks a lot.

 

[Albert Schlef]

Then you can use instance_method(), which is like method() except it
returns an *unbound* method:

def executer(obj, unbound_method)
unbound_method.bind(obj).call(1234)
end

class X
def test(x)
p x
end
end

o1 = X.new
o2 = X.new
o3 = X.new
method = X.instance_methodtest)

executer(o1, method)
executer(o2, method)
executer(o3, method)