Ruby equivalent for Lua first-class functions?

[Dolazy]

I think one of Lua's nice features is that all functions are first-
class functions. That makes it possible to override behavior like
this:

-- Sample stolen from Wikipedia
local oldprint = print -- Store current print function as
oldprint
print = function(s) -- Redefine print function
if s == "foo" then
oldprint("bar")
else
oldprint(s)
end
end

How would you write the above sample using Ruby?


Grtz,
Francis

 

[Luis Lavena]

I think one of Lua's nice features is that all functions are first-
class functions. That makes it possible to override behavior like
this:

-- Sample stolen from Wikipedia
local oldprint = print           -- Store current print function as
oldprint
print = function(s)              -- Redefine print function
  if s == "foo" then
    oldprint("bar")
  else
    oldprint(s)
  end
end

How would you write the above sample using Ruby?

Grtz,
Francis

module Kernel
alias_method ld_print, rint
def my_print(*args)
old_print "bar"
end
alias_method rint, :my_print
end

irb(main):017:0> print "hey"
bar
=> nil

There are several approaches to achieve the same, that's the beauty or
the curse of Ruby

As more complex example, you can check how rubygems replace 'require'
functionality to be able to pick code outside the default $LOAD_PATH.

HTH,