OOP: Using 'self'?

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#1

Quick question: how can I structure the following so ‘self’ does not have to be defined in Function?

Current:

command = {
	Name = "test101";
	Aliases	= {};
	Prefixes = {settings.Prefix};
	Rank = 1;
	RankLock = false;
	Loopable = false;
	Tags = {};
	Description = "";
	Contributors = {};
	--
	Args = {};
	Function = function(self)
		print(self.Name)
	end;
	--
};

command:Function()

test101

Target:

Function = function()
	print(self.Name)
end;

Only a few commands require the self variable so it seems slightly redundant to have to define it every time.

Thanks.

1 Like
#2

In Lua, the following are functionally equivalent:

Class.Function = function(self)
	print(self.Name)
end

function Class.Function(self)
	print(self.Name)
end

function Class:Function()
	print(self.Name)
end

With the colon, self is created as a variable implicitly and doesn’t require the declaration in the arguments. It is similar for calling where Workspace.GetChildren(Workspace) is functionally equivalent to Workspace:GetChildren(). For your example, you would want to move to something like this:

command = {
	Name = "test101";
	Aliases	= {};
	Prefixes = {settings.Prefix};
	Rank = 1;
	RankLock = false;
	Loopable = false;
	Tags = {};
	Description = "";
	Contributors = {};
	--
	Args = {};
	--
};

function command:Function()
	print(self.Name)
end

command:Function()
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78: attempt to perform arithmetic on local 'Value' (a nil value)
#3

If the command was structured as a Table instead of a Dictionary, would this still be possible? For example:

{
	Name = "test101";
	Aliases	= {};
	Prefixes = {settings.Prefix};
	Rank = 1;
	RankLock = false;
	Loopable = false;
	Tags = {};
	Description = "";
	Contributors = {};
	--
	Args = {};
	Function = function(self)
		print(self.Name)
	end;
	--
};
{...};
{...};
#4

I don’t believe it is possible since it is impossible to use the colon syntax inside a table. Having the self (or _ to show it is not being used) would be required for every function without redesigning how it is set up.

1 Like
#5

Appreciate the help! I think I’ll keep self as the final parameter for now then to avoid the repeated unnecessary use.

#6

If you are passing multiple parameters, keep in mind you will need to format your functions a bit differently since self is implicitly used as the first argument since calling something with Class:Function(Arg1,Arg2,...) is the same as calling Class.Function(Class,Arg1,Arg2,...). Ex:

local Command = {
	Name = "Test Command",
	Function = function(Arg1,Arg2,self)
		print(self.Name)
	end,
}

Command.Function("Some string",5,Command)
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#7

Got this covered - I’ll be doing the following instead:

command.Function(speaker, args, command)
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#8

If you plan on making multiple commands, you can avoid including the function in every command object by using a __index metamethod/metaproperty that references a table which has the shared functions between all command objects.

local CommandAPI = {}
function CommandAPI:Function()
    print(self.Name)
end

local function Command(struct)
    return setmetatable(struct, {
        __index = CommandAPI
    })
end

local cmd_1 = Command {
	Name = "test101";
	Aliases	= {};
	Prefixes = {settings.Prefix};
	Rank = 1;
	RankLock = false;
	Loopable = false;
	Tags = {};
	Description = "";
	Contributors = {};
	--
	Args = {};
	Function = function(self)
		print(self.Name)
	end;
	--
};
local cmd_2 = Command {...};
local cmd_3 = Command {...};

You could also store the Command metatable for efficiency, but I’ve inlined it for simplicity.

1 Like