isNil: Difference between revisions

Revision as of 23:38, 17 August 2021

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Description:: Tests whether the variable given by its name is nil or undefined, or whether the given expression evaluates to nil or Nothing.
ⓘ
1.00 This command doesn't exist in Operation Flashpoint but can be emulated (see Example 5).
Groups:: Variables

Syntax:: isNil variableName
Parameters:: variableName: String - name of a missionNamespace variable (e.g "someVar") or a local variable (e.g "_someVar")
Return Value:: Boolean - true if variable is nil

Syntax:

isNil code

Parameters:

code: Code - code to evaluate:

the code will be executed; isNil { player setDamage 1; }; will kill the player
the code will not be allowed to suspend while expression is evaluated, even if the parent scope allows it (see Example 4).

Return Value:

Boolean - true if code returns something other than Nothing

Example 1:: if (isNil "pokus") then { pokus = 0; };
Example 2:: isNil { player getVariable "someVar" };
Example 3:: _myArray = [0, 1]; isNil { _myArray select 0 }; // returns false isNil { _myArray select 1 }; // returns false isNil { _myArray select 2 }; // returns true isNil { _myArray select 3 }; // throws a script error. only length+1 select is allowed
Example 4:: You can do this trick to force execute something in Unscheduled Environment.spawn { systemChat str canSuspend; // chat shows true isNil {hint str canSuspend}; // hint shows false };
Example 5:: Operation Flashpoint workaround:
SQS syntax: _nil = format ["%1", _undefinedVariable] ? (format ["%1", foo] == _nil) : foo = "value" SQF syntax: _nil = format ["%1", _undefinedVariable]; if (format ["%1", foo] == _nil) then { foo = "value"; };

: 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

@@ Line 19: / Line 19: @@
 |descr= Tests whether the variable given by its name is [[nil]] or undefined, or whether the given expression evaluates to [[nil]] or [[Nothing]].
-{{Feature | Informative | {{GVI|ofp|1.00}} This command doesn't exist in {{ofp}} but can be emulated (see '''[[#Examples|Example 5]]''').}}
+{{Feature | Informative | {{GVI|ofp|1.00}} This command doesn't exist in {{ofp}} but can be emulated (see '''{{HashLink|#Example 5}}''').}}
 |s1= [[isNil]] variableName
@@ Line 31: / Line 31: @@
 |p21= code: [[Code]] - code to evaluate:
 * the code '''will''' be executed; {{ic|[[isNil]] { [[player]] [[setDamage]] 1; };}} ''will'' kill the player
-* the code will not be allowed [[canSuspend|to suspend]] while expression is evaluated, even if the parent scope allows it (see '''[[#Examples|Example 4]]''').
+* the code will not be allowed [[canSuspend|to suspend]] while expression is evaluated, even if the parent scope allows it (see '''{{HashLink|#Example 4}}''').
 |r2= [[Boolean]] - [[true]] if code returns something other than [[Nothing]]