AddCommandHandler

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Revision as of 16:39, 27 November 2010 by Ransom (talk | contribs) (→‎Syntax)
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This template is no longer in use as it results in poor readability. This function will attach a scripting function (handler) to a console command, so that whenever a player or administrator uses the command the function is called.

Multiple command handlers can be attached to a single command, and they will be called in the order that the handlers were attached. Equally, multiple commands can be handled by a single function, and the commandName parameter used to decide the course of action.

For users, a command is in the format:

commandName argument1 argument2

This can be triggered from the player's console or directly from the chat box by prefixing the message with a forward slash (/). For server side handlers, the server admin is also able to trigger these directly from the server's console in the same way as they are triggered from a player's console.

Syntax

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Server
bool addCommandHandler ( string commandName, function handlerFunction, [bool restricted = false, 
bool caseSensitive = true] )

Required Arguments

  • commandName: This is the name of the command you wish to attach a handler to. This is what must be typed into the console to trigger the function.
  • handlerFunction: This is the function that you want the command to trigger, which has to be defined before you add the handler. This function can take two parameters, playerSource and commandName, followed by as many parameters you expect after your command (see below). These are all optional.

Optional Arguments

NOTE: When using optional arguments, you might need to supply all arguments before the one you wish to use. For more information on optional arguments, see optional arguments.

  • restricted: Specify whether or not this command should be restricted by default. Use this on commands that should be inaccessible to everyone as default except special users specified in the ACL (Access Control List). This is to make sure admin commands such as ie. 'punish' won't be available to everyone if a server administrator forgets masking it in ACL. This argument defaults to false if nothing is specified.
  • caseSensitive: Specifies if the command handler will ignore the case for this command name.
Click to collapse [-]
Client
bool addCommandHandler ( string commandName, function handlerFunction, [bool caseSensitive = true] )

Required Arguments

  • commandName: This is the name of the command you wish to attach a handler to. This is what must be typed into the console to trigger the function.
  • handlerFunction: This is the function that you want the command to trigger, which has to be defined before you add the handler. This function can take two parameters, playerSource and commandName, followed by as many parameters you expect after your command (see below). These are all optional.

Optional Arguments

NOTE: When using optional arguments, you might need to supply all arguments before the one you wish to use. For more information on optional arguments, see optional arguments.

  • caseSensitive: Specifies if the command handler will ignore the case for this command name.

Handler function parameters

These are the parameters for the handler function that is called when the command is used.

Click to collapse [-]
Server
player playerSource, string commandName, [string arg1, string arg2, ...]
  • playerSource: The player who triggered the command. If not triggered by a player (e.g. by admin), this will be false.
  • commandName: The name of the command triggered. This is useful if multiple commands go through one function.
  • arg1, arg2, ...: Each word after command name in the original command is passed here in a seperate variable. If there is no value for an argument, its variable will contain nil. You can deal with a variable number of arguments using the vararg expression, as shown in Example 4 below.
Click to collapse [-]
Client
 string commandName, [string arg1, string arg2, ...]
  • commandName: The name of the command triggered. This is useful if multiple commands go through one function.
  • arg1, arg2, ...: Each word after command name in the original command is passed here in a seperate variable. If there is no value for an argument, its variable will contain nil. You can deal with a variable number of arguments using the vararg expression, as shown in Example 4 below.

Returns

Returns true if the command handler was added successfully, false otherwise.

Example

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Server

Example 1: This example defines a command handler for the command createmarker. This will create a red marker at the position of the player player who uses it. 

-- Define our function that will handle this command
function consoleCreateMarker ( playerSource )
	-- If a player triggered it (rather than the admin) then
	if ( playerSource ) then
		-- Get that player's position
		local x, y, z = getElementPosition ( playerSource )
		-- Create a size 2, red checkpoint marker at their position
		createMarker ( x, y, z, "checkpoint", 2, 255, 0, 0, 255 )
		-- Output it in his chat box
		outputChatBox ( "You got a red marker", playerSource )
	end
end
-- Attach the 'consoleCreateMarker' function to the "createmarker" command
addCommandHandler ( "createmarker", consoleCreateMarker )

Example 2: A simple health setting command. If a player types /sethealth X in the chatbox his health will be set to X. Note that the function setElementHealth is used rather than something like "setPlayerHealth". This function is more generic and can also be used to set the health of vehicles. 

function consoleSetHealth(playerSource, commandName, health)
	setElementHealth(playerSource, tonumber(health))
end
addCommandHandler("sethealth", consoleSetHealth)

Example 3: This example implements a set_vehicle_color command. 

-- Define our function that will handle this command
function consoleSetVehicleColor ( playerSource, commandName, col1, col2, col3, col4 )
	-- If a player triggered this in-game
	if ( playerSource ) then
		-- Get the player's vehicle
		local playerVehicle = getPedOccupiedVehicle ( playerSource )
		-- If the player is in a vehicle and we've got at least 1 parameter
		if ( playerVehicle and col1 ) then
			-- Get the vehicle's existing color and use it if fewer than 4 arguments were passed
			local exCol1, exCol2, exCol3, exCol4 = getVehicleColor ( playerVehicle )

			if not col2 then col2 = exCol2 end
			if not col3 then col3 = exCol3 end
			if not col4 then col4 = exCol4 end

			-- Set the vehicle's color
			setVehicleColor ( playerVehicle, col1, col2, col3, col4 )
		else
			-- If we didn't get at least 1 parameter or the player doesn't have a vehicle, display some help text
			outputConsole ( "This function will set your current vehicle's colors. A vehicle can have up to 4 colors.", playerSource )
			outputConsole ( "Syntax: set_vehicle_color color1 [ color2 color3 color4 ]", playerSource )
			outputConsole ( "You must be in a vehicle to use this function.", playerSource )
		end
	end
end
-- Attach the 'consoleSetVehicleColor' function to the "set_vehicle_color" command
addCommandHandler ( "set_vehicle_color", consoleSetVehicleColor )

Example 4: This example makes use of Lua's vararg expression to implement a check_parameters command to count the number of parameters passed, merge them all into a single string and output it. This is also shows you how you can use table.concat to merge all the passed arguments. This is particularly useful when you want to read in a sentence of text passed from the user. 

-- Define our function that will handle this command (which can accept a variable number of arguments after commandName)
function consoleCheckParameters ( playerSource, commandName, ... )
	-- If a player, not an admin, triggered it,
	if playerSource then
		-- Get the number of arguments in the arg table (arg table is the same as: {...})
		local parameterCount = #arg
		-- Output it to the player's chatbox
		outputChatBox ( "Number of parameters: " .. parameterCount, playerSource )
		-- Join them together in a single comma-separated string
		local stringWithAllParameters = table.concat( arg, ", " )
		-- Output this parameter list to the player's chatbox
		outputChatBox ( "Parameters passed: " .. stringWithAllParameters, playerSource )
	end
end
-- Attach the 'consoleCheckParameters' function to the "check_parameters" command
addCommandHandler ( "check_parameters", consoleCheckParameters )

Example 5: This example shows using a single function to handle multiple command handlers. This isn't advised for general usage, as it makes code harder to understand, but where multiple command handlers share some logic, it can be a useful way of reducing duplicated code. Generally, it would be preferable to put this shared logic in a separate function instead, as this gives you more control over the flow. 

-- make the function
function moneyCmd(player, cmd, amount)
    if getElementData(player, "canUseMoneyFunctions") then -- the shared logic
        if cmd == "givemoney" then
            amount  = tonumber(amount)
            if amount then
                givePlayerMoney(player, amount)
            else
                outputChatBox("[usage] /givemoney [amount]", player)
            end
        else if cmd == "takemoney" then
            amount = tonumber(amount)
            if amount then
                takePlayerMoney(player, amount)
            else
                outputChatBox("[usage] /takemoney [amount]", player)
            end
        end
    else
        outputChatBox("You aren't able to use this command", player)
    end
end
 
addCommandHandler("givemoney", moneyCmd);
addCommandHandler("takemoney", moneyCmd);
Click to collapse [-]
Client

Example 1: This creates a GUI window and allows a player to change its alpha (transparency) value with a command. Note that, in a clientside script, the player using the command is not passed as a parameter to the handler function, since it is always the local player. 

--Create a window
myWindow = guiCreateWindow ( 0.30, 0.10, 0.5, 0.60, "GUI window title", true )

--Add a command handler to change the alpha of the GUI window. Usage example: 'alpha 0.15'
function changeAlpha ( commandName, alphaAmount )
	-- All command parameters are strings, so we'll convert the value to a number first
	alphaAmount = tonumber(alphaAmount)
	guiSetAlpha ( myWindow, alphaAmount )
end
addCommandHandler ( "alpha", changeAlpha )

See Also


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