: vs .

[unhandyandy]

To what if any extent is the object:function (versus object.function) syntax supported?

[hoelzro]

@unhandyandy Do you mean on the Perl side? Could you give an example?

[unhandyandy]

Suppose I have a table

object = { 'y' : 5 }

I'm wondering what happens if I define a function like

function object:action( x )
    return self.y + x
end

Will I be able to make a call within the same inline lua section like

object:action( 3 )

and get 8?

Or should I stick strictly to the dot (.) notation?

[hoelzro]

In Lua, : and . for function calling mean something slightly different. object:method(args) is semantical identical to object.method(object, args). Rule of thumb: if you define a function with :, or if a function has a self parameter, chances are you should use :.

[unhandyandy]

Right, but my question is whether this behavior is supported in Inline::Lua. I guess the answer is yes.

[hoelzro]

Correct =)

[unhandyandy]

OK, maybe this is just my daily confusion, but I've got a function defined like this.

function class:action()
....

I assumed that there were two ways of calling it:

instance:action()

(where instance copies class' table) or

instance.action( instance )

however both of those just return the value instance itself. The call that works correctly is

instance.action()

which I would have thought should not work. Is this a 5.1 thing (I'm more familiar with 5.2)? Maybe the problem is that I'm not using the metatable (since you said it doesn't work with Inline)?

[hoelzro]

AFAIK, the way . and : work hasn't changed since 5.1. If you have something defined as function class:action, you almost always need to call it as instance:action(). Could you paste the full example of code you're trying?

[unhandyandy]

What if you define a function by

testfun = function  ( self )
   local root = math.random( 0, 9 )
   return root
end

how then should you call it? Here's a MWE.

package mwe;

use Inline 'Lua';
use Inline (Config => DIRECTORY => "/tmp/");

use Inline 'Lua' => <<'LUA';

testclass = {}

function testclass:generate(  ) 
   local chcs
   chcs = self:submaker(  )
   return chcs
end


function testclass:new(  )
   local instance = {}
   instance.generate = testclass.generate
   instance.submaker = testfun
   return instance
end


testfun = function  ( self )
   local root = math.random( 0, 9 )
   return root
end

function proto()
   return testclass:new(  )
end

LUA

1;

I would have thought that the call

chcs = self:submaker(  )

was correct, but when I call this code from Perl this is what happens.

$test= mwe::proto();
$test->{generate}->($test)  ## returns the object itself, i.e.
                            ## $VAR1 = { 'generate' => sub { "DUMMY" }, 
                            ## 'submaker' => sub { "DUMMY" } }; 
                            ## when dumped
$test->{submaker}->($test) ## returns a number 0-9

But when I replace that call by one that looks wrong, i.e.

chcs = self.submaker(  )

the perl code line 2 correctly returns a number.

[hoelzro]

Ok, this is really weird; I have no idea why it returns a table in your example. I won't be available for the rest of the weekend, but I'll try to look at it when I have a chance.

[unhandyandy]

No hurry. You've already gone above and beyond in your help for me.

I wonder if it might have to with my testfun not actually using the argument self. Perhaps on the Perl side that results in @_ not being fully consumed, and the self argument that was passed remaining on top of the stack?

[hoelzro]

@unhandyandy Ok, so I've dug into this...and you've found a bug! I fixed the bug and uploaded Inline::Lua 0.10 to PAUSE. It should work properly now.

[unhandyandy]

Awesome, thanks!