Re: Functional objects
[
Date Prev][
Date Next][
Thread Prev][
Thread Next]
[
Date Index]
[
Thread Index]
- Subject: Re: Functional objects
- From: Mark Hamburg <mhamburg@...>
- Date: 2004年9月23日 08:18:59 -0700
One loses direct read/write access to attributes, but closure-based (which
is probably a better term than functional now that I think about it) can
certainly have data as closure values. In fact, this data is more private
and accessed more efficiently since it doesn't involve a table lookup.
Lacking a switch statement, however, method dispatch itself is slower.
function makeObject()
local attribute = 1
return function( msg, param )
if msg == "attribute" then
return attribute
elseif msg == "setAttribute" then
attribute = param
elseif msg == "method" then
-- method code goes here
else
error( "Unknown message: " .. tostring( msg ) )
end
end
end
In Lua as it presently exists, one needs to write:
obj( "attribute" )
obj( "setAttribute", 2 )
obj( "method" )
With the proposed change one could write:
obj:attribute()
obj:setAttribute( 2 )
obj:method()
Now, it is true that this also enables one to write
print:hello()
but it doesn't create pressure to do so.
Mark
on 9/22/04 12:43 PM, Bilyk, Alex at ABilyk@maxis.com wrote:
> And still this would only apply to those 'objects' that don't have any
> attributes.
>
> given a table 'object'
>
> table_object =
> {
> method = function () end,
> attribute = 1
> }
>
> table_object.attribute = 2
> table_object : method()
>
> How can one convert this into a functional one? So, the proposed feature would
> only apply to objects that effectively are bags of functions with no data.
> Right? I think, practically, most objects people are dealing with have both
> methods and attributes. Given an function based object, can one use attributes
> with them?
>
> like
>
> function_object:method() --> function_object("method")
> function_object.attribute --> ???