Q: How to call parent method explistly?

Ruby
#1

Is it possible to call parent method specifying method name explicitly
like super.foobar() or parent::foobar()?

class Parent
   def hello(name)
     puts "Hello #{name}!"
   end
end

class Child
  def hello(name)
    # ...
    _hello(name)
    # ...
  end
  private
  def _hello(name)
    # ...
    super(name)   # want to call Parent#hello(), not _hello()
    # ...
  end
end
#2

On Feb 22, 2011, at 6:25 PM, makoto kuwata wrote:

Is it possible to call parent method specifying method name explicitly
like super.foobar() or parent::foobar()?

There are a couple of alternatives.

  1. Create an alias of the parent’s method and call it instead:

class Child < Parent
alias parent_hello hello
def _hello(name)
parent_hello(name)
end
end

  1. use a method object to reference the parent’s method:

class Child < Parent
def parent_hello(*args)
Parent.instance_method(:hello).bind(self).call(*args)
end

def _hello(name)
parent_hello(name)
end
end

Gary W.

#3

On Wed, Feb 23, 2011 at 1:09 AM, Gary W. [email protected] wrote:

class Child < Parent
Parent.instance_method(:hello).bind(self).call(*args)
end

def _hello(name)
parent_hello(name)
end
end

Folks, why are you making this so complicated? Nobody mentions the
standard way of doing this by using “super”:

class Parent
def hello_same_args(a)
puts a
end

def hello_different_args
puts “We don’t need args”
end
end

class Child < Parent
def hello_same_args(a)
super
puts “now in child”
end

def hello_different_args(x)
super()
puts “Child got #{x}”
end
end

irb(main):022:0> Child.new.hello_same_args “ARG”
ARG
now in child
=> nil
irb(main):023:0> Child.new.hello_different_args “ARG”
We don’t need args
Child got ARG
=> nil

Only if you want to call a different method in the super class you
need to use one of the other approaches. But if you think about it,
usually this is not needed.

Kind regards

robert

#4

It’s ugly but this works (i assume Child subclasses Parent?)

class Child < Parent
  def _hello(name)
    Parent.instance_method(:hello).bind(self).call(name)
  end
end

makoto kuwata wrote in post #983231:

Is it possible to call parent method specifying method name explicitly
like super.foobar() or parent::foobar()?

class Parent
   def hello(name)
     puts "Hello #{name}!"
   end
end

class Child
  def hello(name)
    # ...
    _hello(name)
    # ...
  end
  private
  def _hello(name)
    # ...
    super(name)   # want to call Parent#hello(), not _hello()
    # ...
  end
end
#5

On Feb 24, 2011, at 3:59 AM, Robert K. wrote:

Folks, why are you making this so complicated? Nobody mentions the
standard way of doing this by using “super”:
[…]
Only if you want to call a different method in the super class you
need to use one of the other approaches. But if you think about it,
usually this is not needed.

The original poster specifically asked about calling a different
method in the parent that was also redefined in the child,
which is why I didn’t show the use of super. From the original
message:

super(name) # want to call Parent#hello(), not _hello()

Gary W.

#6

On 24.02.2011 20:25, Gary W. wrote:

The original poster specifically asked about calling a different
method in the parent that was also redefined in the child,
which is why I didn’t show the use of super. From the original
message:

super(name) # want to call Parent#hello(), not _hello()

Ah, that was the piece I missed. Sorry for the noise.

I’d still question the wisdom of such a design though.

Kind regards

robert