Ruby equivalent for Lua first-class functions?


#1

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


#2

On Nov 15, 12:12 pm, Dolazy removed_email_address@domain.invalid wrote:

else
oldprint(s)
end
end

How would you write the above sample using Ruby?

Grtz,
Francis

module Kernel
alias_method :old_print, :print
def my_print(*args)
old_print “bar”
end
alias_method :print, :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 :slight_smile:

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

HTH,