params

From Bohemia Interactive Community
Jump to: navigation, search
Introduced with Arma 3 version 1.48
  

Click on the images for descriptions

Introduced in

Game:
Arma 3
Version:
1.48

Description

Description:
Parses input argument into array of private variables. When used without argument, as shown in main syntax, internal variable _this, which is usually available inside functions and event handlers, is used as argument.

In addition to simple parsing directly into variables, input can be tested in case it is undefined, of the wrong type or of the wrong size (if array) and substituted if necessary with default values. Since Arma 3 v1.53.132691, onscreen errors are displayed for when the input is of the wrong type or size.

Syntax

Syntax:
params [element1, element2,...elementN]
Parameters:
[element1, element2,...elementN]: Array - format array
elementN: String or Array
If String then it is the name of a private variable (must begin with underscore _, e.g. "_myVar")
If Array then it should be one of the following constructs:
  • [variableName, defaultValue]
  • [variableName, defaultValue, expectedDataTypes]
  • [variableName, defaultValue, expectedDataTypes, expectedArrayCount]
variableName: String - name of a private variable (must begin with underscore _, e.g. "_myVar")
defaultValue: Anything - default value to return if input element is undefined, of the wrong type or of the wrong size (if array).
expectedDataTypes (Optional): Array of direct Data Types - checks if passed value is one of listed Data Types. If not, default value is used instead. Empty array [] means every data type is accepted.
expectedArrayCount (Optional): Number or Array - a single size or array of sizes. If passed input value is an array, checks that it has a certain number of elements. If not, default value is used instead. Empty array [] means any size is accepted.
Return Value:
Boolean - false if error occurred or default value has been used, otherwise true

Alternative Syntax

Syntax:
argument params [element1, element2,...elementN]
Parameters:
argument: Anything - A usual array of params is expected. If a non-array argument is passed, it will be converted to 1 element array
[element1, element2,...elementN]: Array - format array
elementN: String or Array:
If String then it is the name of a private variable (must begin with underscore _, e.g. "_myVar")
If Array then it should be one of the following constructs:
  • [variableName, defaultValue]
  • [variableName, defaultValue, expectedDataTypes]
  • [variableName, defaultValue, expectedDataTypes, expectedArrayCount]
variableName: String - name of a private variable (must begin with underscore _, e.g. "_myVar")
defaultValue: Anything - default value to return if input element is undefined, of the wrong type or of the wrong size (if array).
expectedDataTypes (Optional): Array of direct Data Types - checks if passed value is one of listed Data Types. If not, default value is used instead. Empty array [] means every data type is accepted.
expectedArrayCount (Optional): Number or Array - a single size or array of sizes. If passed input value is an array, checks that it has a certain number of elements. If not, default value is used instead. Empty array [] means any size is accepted.
Return Value:
Boolean - false if error occurred or default value has been used, otherwise true

Examples

Example 1:
[1, 2, 3] call { private ["_one", "_two", "_three"]; _one = _this select 0; _two = _this select 1; _three = _this select 2; // ..... }; // Same as above, only using params [1, 2, 3] call { params ["_one", "_two", "_three"]; // ..... };
Example 2:
[123] call { params ["_myvar"]; }; // Below would produce the same result as above 123 call { params ["_myvar"]; };
Example 3:
position player params ["", "", "_z"]; if (_z > 10) then { hint "YOU ARE FLYING!"; };
Example 4:
[1, nil, 2] params ["_var1", "_var2", "_var3"]; // All 3 variables are made private but only _var1 and _var3 are defined [1, nil, 2] params ["_var1", ["_var2", 23], "_var3"]; // All 3 variables are private and defined
Example 5:
[1, 2] call { if (!params ["_var1", "_var2", ["_var3", true, [true]]]) exitWith { hint str [_var1, _var2, _var3]; }; }; // The hint shows [1,2,true] //Script exits, default value was used due to missing value [1, 2, 3] call { if (!params ["_var1", "_var2", ["_var3", true, [true]]]) exitWith { hint str [_var1, _var2, _var3]; }; }; // The hint shows [1,2,true] //Script exits, default value was used due incorrect value type
Example 6:
[1, "ok", [1, 2, 3]] call { if (!params [ ["_var1", 0, [0]], ["_var2", "", [""]], ["_var3", [0,0,0], [[], objNull, 0], [2,3]] ]) exitWith {}; hint "ok"; }; // Passes validation [1, 2, [3, 4, 5]] call { if (!params ["_var1", "_var2", ["_var3", [], [[], objNull, 0], 0]]) exitWith {}; hint "ok"; }; // Fails, because passed array is expected to be of 0 length, i.e. empty
Example 7:
position player params ["_x", "_y"]; player setPos [_x, _y, 100];
Example 8:
[1, 2, 3, [4, 5, 6]] call { params ["_one", "_two", "_three"]; _this select 3 params ["_four", "_five", "_six"]; };
Example 9:
{ _x params ["_group", "_index"]; // ..... } forEach waypoints group player; fn_someFnc = { params ["_position", ["_direction", 0], ["_name", ""]]; // Extract the x, y, and z from "_position" array: _position params ["_x", "_y", "_z"]; // ..... }; [position player, direction player, name player] call fn_someFnc;
Example 10:
targ addEventHandler ["HitPart", { _this select 0 params ["_target", "_shooter", "_projectile"]; }];

Additional Information

Multiplayer:
-
See also:
paramselectsetresizereverseinfindtoArraytoStringforEachcountdeleteAtdeleteRangeappendsortarrayIntersectsplitStringjoinStringisEqualTypeAllisEqualTypeisEqualTypeParamsisEqualTypeArrayisEqualTypeAnytypeNameBIS_fnc_param

Notes

Only post proven facts here. Report bugs on the feedback tracker. Use the talk page or the forums for discussions.
Add New Note | How To
Posted on August 30, 2015 - 21:59 (UTC)
Killzone Kid
Because params doubles as private, instead of: [1, 2, 3] params ["_one", "_two", "_three"]; private "_four"; _four = 4; You can just: [1, 2, 3] params ["_one", "_two", "_three", "_four"]; _four = 4;
Posted on November 3, 2016 - 04:07 (UTC)
Dedmen
With a function only taking one Parameter, it doesn't matter whether the parameter is in an array or not:
Example: 1 call { params [ ["_number",0, [0]] ]; }; or [1] call { params [ ["_number",0, [0]] ]; }; But when the one Parameter is an array that parameter has to be inside of an array when the function is called
Example: [1,2] call { params [ ["_array", [], [[]], 2] ]; };//Fails [[1,2]] call { params [ ["_array", [], [[]], 2] ]; };//Succeeds