call

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Description

Description:
Adds given set of compiled instructions to the current stack and waits for it to finish and return, provides an option to pass arguments to the executed Code. See Scheduler to learn more about how the code is executed and behaves.
Groups:
Program Flow

Syntax 1

Syntax:
call code
Parameters:
code: Code - compiled instructions
Operation Flashpoint
Operation Flashpoint takes String.
This way of calling has access to its parent scope's _this, as all it does is creating a scope.
Return Value:
Anything - the last value given in the function is returned - see the topic Function for more information

Syntax 2

Syntax:
args call code
Parameters:
args: Anything - arguments that are passed to the function in the _this variable.
code: Code - compiled instructions
Operation Flashpoint
Operation Flashpoint takes String.
Return Value:
Anything - the last value given in the function is returned. See the topic Function for more information.

Syntax 3

Syntax:
hashMapObj call [methodName, arguments]
Parameters:
hashMapObj: HashMap - the HashMap (not necessarily created through createHashMapObject) to call the method on
methodName: String - the name of the method to call (the method must be defined in hashMapObj; see createHashMapObject)
arguments: Anything - (Optional, default nil) arguments that are passed to the method in the _this variable
Return Value:
Anything - the value returned by the methodName method

Examples

Example 1:
call { hint str 123; };
Example 2:
123 call { hint str _this; };
Example 3:
_sum = [1, 2] call { (_this select 0) + (_this select 1); }; hint str _sum; // displays 3
Example 4:
123 call compile "hint str _this;";
Example 5:
_result = 123 call compile preprocessFileLineNumbers "myFile.sqf";
Example 6:
private _hashMapObj = createHashMapObject [[ ["MyMethod", { systemChat ("MyMethod has been called with the following arguments: " + str _this); }] ]]; _hashMapObj call ["MyMethod", ["Hello there", player, 123]]; // hints 'MyMethod has been called with the following arguments: ["Hello there", player, 123]'

Additional Information

See also:
spawn execVM canSuspend compile compileScript preprocessFile remoteExec remoteExecCall

Notes

Report bugs on the Feedback Tracker and/or discuss them on the Arma Discord or on the Forums.
Only post proven facts here! Add Note
Leopard20 - c
Posted on Nov 05, 2021 - 10:52 (UTC)
Contrary to a widespread misconception in the community, call doesn't necessarily execute the code in the Unscheduled Environment. Call simply means: "execute the code here", just like how you execute a code using then (if (true) then _code) or do. Therefore it does not change the environment:
call executed in environment: Resulting environment of the code:
Scheduled Scheduled
Unscheduled Unscheduled

This means that doing something like this (which is misused very often):

private _handle = _params spawn MY_fnc_Function; waitUntil { scriptDone _handle };

is not needed, because a lot of performance would be wasted compared to simply doing this:

_params call MY_fnc_Function;

which does the exact same thing as the previous code, except no new "scheduler thread" is created and the function executes seamlessly, plus the added performance benefit as mentioned before.
If it is necessary to execute a code in the Unscheduled Environment, one can use isNil instead:

isNil {_params call MY_fnc_Function}; // MY_fnc_Function is always executed unscheduled, regardless of the current environment

or if there are no parameters, one can simply do this:

isNil MY_fnc_Function