Re-binding Proc

Ruby
1

Is there a way to call a proc while passing in the binding/scope for
‘self’? I found an un-responded-to question on this (ruby-talk:12794)
in 2001 which implies that, at least then, there was no way to do it.

What I’m doing:
class Foo
@@handlers = {}

def self.handle_type( type, &proc )
@@handlers[ type ] = proc
end

attr_reader :name
def initialize( name )
@name = name
end

def do_thing( type )
@@handlers[ type ].call( self )
end
end

Foo.handle_type( :showname ){ |me|
puts “My name is ‘#{me.name}’”
}

f = Foo.new( ‘f’ )
f.do_thing( :showname )
#=> My name is ‘f’

What I’d like to do instead:

Foo.handle_type( :showname ){
puts “My name is ‘#{self.name}’”
}

2

Damn, hit send too soon. continues

I realize that I can do this by defining a method (as below), but for
some reason that feels bad to me. I’d like to do it with Proc objects,
if possible.

Works by spamming the method namespace.

class Foo
def self.handle_type( type, &proc )
define_method( “dothing_#{type}”, &proc )
end

…

def do_thing( type )
send “dothing_#{type}”
end
end

3

Phrogz wrote:

Is there a way to call a proc while passing in the binding/scope for
‘self’? I found an un-responded-to question on this (ruby-talk:12794)
in 2001 which implies that, at least then, there was no way to do it.

I may be just feeling light-headed from COBOL, but
would #instance_eval not work here?

What I’m doing:
class Foo
@@handlers = {}

def self.handle_type( type, &proc )
@@handlers[ type ] = proc
end

attr_reader :name
def initialize( name )
@name = name
end

def do_thing( type )
@@handlers[ type ].call( self )

  instance_eval &@@handlers[type]

end
end

Foo.handle_type( :showname ){ |me|
puts “My name is ‘#{me.name}’”
}

Foo.handle_type(:showname) {puts “My name is #{self.name}”}

f = Foo.new( ‘f’ )
f.do_thing( :showname )
#=> My name is ‘f’

What I’d like to do instead:

Foo.handle_type( :showname ){
puts “My name is ‘#{self.name}’”
}