OpenEuphoria

Re: Prototype-Based Programming

• Posted by mattlewis (admin) Sep 26, 2013
• 2249 views

I whipped up a really simple framework for doing prototype based programming in euphoria. This probably duplicates some of the old OOP libraries in the archive, except that it uses euphoria's maps and it has no error checking.

-- prototype.e 
namespace proto 
 
include std/map.e 
 
public type prototype( object p ) 
	return map( p ) 
end type 
 
public function new( object p = "" ) 
	if prototype( p ) then 
		return map:copy( p ) 
	else 
		return map:new() 
	end if 
end function 
 
public function call( prototype p, object method, object args = {}) 
	if atom( args ) then 
		args = { p, args } 
	else 
		args = prepend( args, p ) 
	end if 
	return call_func( map:get( p, method ), args ) 
end function 
 
public function get( prototype p, object property ) 
	return map:get( p, property ) 
end function 
 
public procedure set( prototype p, object property, object value ) 
	map:put( p, property, value ) 
end procedure 

...and then it could be used like so:

-- prototype.ex 
include prototype.e 
 
enum 
	NAME, 
	LIFEPOINTS, 
	GREET 
 
prototype creature = proto:new() 
 
proto:set( creature, NAME, "" ) 
proto:set( creature, LIFEPOINTS, 100 ) 
 
function person_greeter( prototype p ) 
	printf(1, "Hello, my name is %s\n", { proto:get( p, NAME ) }) 
	return 0 
end function 
 
prototype person = proto:new( creature ) 
proto:set( person, GREET, routine_id("person_greeter") ) 
 
prototype bob = proto:new( person ) 
proto:set( bob, NAME, "Bob" ) 
 
 
function hispanic_greeting( prototype p ) 
	printf(1, "Hola, me llamo %s\n", { proto:get( p, NAME ) }) 
	return 0 
end function 
 
prototype juan = proto:new( person ) 
proto:set( juan, GREET, routine_id("hispanic_greeting" ) ) 
proto:set( juan, NAME, "Juan" ) 
 
 
prototype luis = proto:new( juan ) 
proto:set( luis, NAME, "Luis" ) 
 
proto:call( bob, GREET ) 
proto:call( juan, GREET ) 
proto:call( luis, GREET ) 

$ eui prototype.ex 
Hello, my name is Bob 
Hola, me llamo Juan 
Hola, me llamo Luis 
 

Obviously, any method needs to have the prototype object be its first parameter. Method / property identifiers can be whatever you want. I used an enum, but you could have sequences or whatever there. If you try to "get" something meant as a method, you'll get the routine id, of course. If you try to call a property, you'll likely get an error, unless the value is a valid routine id and your arguments match the signature of the target.

Matt