-= Gametoast.com =-

Posted: **Tue Mar 27, 2018 6:53 am**

Hey there,

i'm really confused by the class system from lua. Maybe someone can explain it to me

this is the original function

Hidden/Spoiler:

[code]

function ObjectiveConquest:AddCommandPost(cp)

	--make sure we have a table to add the cp to

	self.commandPosts = self.commandPosts or {}

	--do all the error checking we can on the cp

	assert(cp.name, "WARNING: no name supplied for the command post")

	cp.name = string.lower(cp.name)

	self.commandPosts[cp.name] = cp

	--keep a running tally of the bleedValue relative to each team

	if not self.totalBleedValue then

		self.totalBleedValue = {}

		self.totalBleedValue[self.teamATT] = 0

		self.totalBleedValue[self.teamDEF] = 0

	end

	self.totalBleedValue[self.teamATT] = self.totalBleedValue[self.teamATT] + GetCommandPostBleedValue(cp.name, self.teamATT)

	self.totalBleedValue[self.teamDEF] = self.totalBleedValue[self.teamDEF] + GetCommandPostBleedValue(cp.name, self.teamDEF)

end

[/code]

that i try to wrap this way:

Hidden/Spoiler:

[code]

if ObjectiveConquest then

	aih_backup = ObjectiveConquest.AddCommandPost

	ObjectiveConquest.AddCommandPost = function(cp, ...)

		print(">>", cp.name)

		uf_print(cp, false, 0)

		return aih_backup(cp, unpack(arg))

	end

else

	print(">> go and find a solution")

end

[/code]

output log:

Hidden/Spoiler:

[code]

>>    nil

uf_print(): Starting:     table: 085B5ACC    function: 085D2904    false    0

Key, Value:     multiplayerRules    true

Key, Value:     textDEF    game.modes.con2

Key, Value:     teamDEF    2

Key, Value:     textATT    game.modes.con

Key, Value:     teamATT    1

uf_print(): Finished:     table: 085B5ACC    false    0

>>    nil

uf_print(): Starting:     table: 085B5ACC    function: 085D2904    false    0

Key, Value:     totalBleedValue    table: 085B5BCC

Key, Value:     commandPosts    table: 085B5BAC

Key, Value:     multiplayerRules    true

Key, Value:     textDEF    game.modes.con2

Key, Value:     teamDEF    2

Key, Value:     textATT    game.modes.con

Key, Value:     teamATT    1

uf_print(): Finished:     table: 085B5ACC    false    0

>>    nil

uf_print(): Starting:     table: 085B5ACC    function: 085D2904    false    0

Key, Value:     totalBleedValue    table: 085B5BCC

Key, Value:     commandPosts    table: 085B5BAC

Key, Value:     multiplayerRules    true

Key, Value:     textDEF    game.modes.con2

Key, Value:     teamDEF    2

Key, Value:     textATT    game.modes.con

Key, Value:     teamATT    1

uf_print(): Finished:     table: 085B5ACC    false    0

>>    nil

uf_print(): Starting:     table: 085B5ACC    function: 085D2904    false    0

Key, Value:     totalBleedValue    table: 085B5BCC

Key, Value:     commandPosts    table: 085B5BAC

Key, Value:     multiplayerRules    true

Key, Value:     textDEF    game.modes.con2

Key, Value:     teamDEF    2

Key, Value:     textATT    game.modes.con

Key, Value:     teamATT    1

uf_print(): Finished:     table: 085B5ACC    false    0

>>    nil

uf_print(): Starting:     table: 085B5ACC    function: 085D2904    false    0

Key, Value:     totalBleedValue    table: 085B5BCC

Key, Value:     commandPosts    table: 085B5BAC

Key, Value:     multiplayerRules    true

Key, Value:     textDEF    game.modes.con2

Key, Value:     teamDEF    2

Key, Value:     textATT    game.modes.con

Key, Value:     teamATT    1

uf_print(): Finished:     table: 085B5ACC    false    0

>>    nil

uf_print(): Starting:     table: 085B5ACC    function: 085D2904    false    0

Key, Value:     totalBleedValue    table: 085B5BCC

Key, Value:     commandPosts    table: 085B5BAC

Key, Value:     multiplayerRules    true

Key, Value:     textDEF    game.modes.con2

Key, Value:     teamDEF    2

Key, Value:     textATT    game.modes.con

Key, Value:     teamATT    1

uf_print(): Finished:     table: 085B5ACC    false    0

[/code]

why does the cp look like that?? In my understanding it should like similar with different name value. But there is no name value.

Posted: **Tue Mar 27, 2018 7:21 am**

Removing some of the syntactic sugar from this should make it easier to understand what is going on here.

Code: Select all

function ObjectiveConquest:AddCommandPost(cp)
end

The above snippet is expanded by the compiler to.

Code: Select all

ObjectiveConquest.AddCommandPost = function (self, cp)
end

We can now see that the presence of the ':' causes the compiler to add the implicit self parameter as the first argument. Now with that knowledge when we look at the closure you're using to hook the function the issue is quite easy to spot.

Code: Select all

ObjectiveConquest.AddCommandPost = function(cp, ...)
end

You're simply treating 'self' as 'cp' and the real 'cp' argument is lost in the variadic pack. Defining your closure accounting for 'self' should fix your issue.

Code: Select all

ObjectiveConquest.AddCommandPost = function(self, cp, ...)
end

The free first edition of Programming in Lua has some excellent info on classes in Lua, it's well worth a read if you have the interest and time. https://www.lua.org/pil/16.html

Posted: **Tue Mar 27, 2018 7:57 am**

works fine, thank you

-= Gametoast.com =-

class system lua general understanding [Solved]

class system lua general understanding [Solved]

Re: class system lua general understanding

Re: class system lua general understanding