try: Difference between revisions

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m (attempt to improve readability of descripiton example.)
m (Fix SQF)
 
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{{Command|= Comments
{{RV|type=command
____________________________________________________________________________________________


| arma |= Game name
|game1= arma1
|version1= 1.00


|1.00|= Game version
|game2= arma2
____________________________________________________________________________________________
|version2= 1.00


| Defines a try-catch structure. This sets up an [[Exception handling|exception handling]] block. Any thrown exception in a try block is caught in a [[catch]] block. The structured exception block has following form:
|game3= arma2oa
try //begin of try-catch block
|version3= 1.50
  { //block, that can throw exception }
catch
  { //block, that process an exception. Exception is described in _exception variable };  |= Description
____________________________________________________________________________________________


| '''try''' code |= Syntax
|game4= tkoh
|version4= 1.00


|p1= code: [[Code]] |= Parameter 1
|game5= arma3
|version5= 0.50


| [[Nothing]] |= Return value
|gr1= Program Flow
____________________________________________________________________________________________


| [[Exception handling]] |= See also
|descr= Defines a try-catch structure. This sets up an [[Exception handling|exception handling]] block. Any thrown exception in a try block is caught in a [[catch]] block. The structured exception block has the following form:
<sqf>try
{ /* block that can throw exception */ }
catch
{ /* block that processes the exception. Exception is described in the _exception variable */ };</sqf>


}}
|s1= [[try]] code
 
|p1= code: [[Code]]
 
|r1= [[Exception handling|Exception Type]]
 
|s2= args [[try]] code
 
|s2since= arma3 1.54
 
|p21= args: [[Anything]] - passed arguments, will be put in ''_this'' variable inside the "code"
 
|p22= code: [[Code]]
 
|r2= [[Exception handling|Exception Type]]
 
|x1= <sqf>try { throw "invalid argument" } catch { hint str _exception };</sqf>
 
|x2= <sqf>123 try { if (_this != 123) throw "invalid argument" } catch { hint str _exception };</sqf>
 
|x3= <sqf>
try {
if (a > b) throw "Error: some error"; // OK
// the command argument is static
} catch {
hint str _exception;
};
 
try {
_someFunc = {
// ...
};
if (a > b) throw (call _someFunc); // NOT OK
// the command argument is dynamic
// _someFunc is called first to get the value regardless of (a > b) outcome
} catch {
hint str _exception;
};


<h3 style="display:none">Notes</h3>
try {
<dl class="command_description">
_someFunc = {
<!-- Note Section BEGIN -->
// ...
};
if (a > b) then {throw (call _someFunc)}; // OK
// the command argument is dynamic
// _someFunc is only called when (a > b) is true
} catch {
hint str _exception;
};
</sqf>


<!-- Note Section END -->
|seealso= [[Exception handling]] [[throw]] [[catch]]
</dl>
}}


<h3 style="display:none">Bottom Section</h3>
{{Note
[[Category:Scripting Commands|TRY]]
|user= Killzone_Kid
[[Category:Scripting Commands ArmA|TRY]]
|timestamp= 20150609205200
[[Category:ArmA: Control Structures|TRY]]
|text= Do not expect this behave like Javascript try catch and ignore all errors. But it does have one useful behaviour. Normally when a runtime error occurs in SQF (unlike when there is compile error) it continues to execute till the end. But if the script is placed in [[try]] {} scope and [[throw]] is used upon error, the script immediately terminates, exits the [[try]] {} scope and enters [[catch]] {} scope. This way it is possible to process possible exceptions in civilised manner.
[[Category:Command Group: Program Flow|TRY]]
}}

Latest revision as of 17:49, 1 November 2022

Hover & click on the images for description

Description

Description:
Defines a try-catch structure. This sets up an exception handling block. Any thrown exception in a try block is caught in a catch block. The structured exception block has the following form:
try { /* block that can throw exception */ } catch { /* block that processes the exception. Exception is described in the _exception variable */ };
Groups:
Program Flow

Syntax

Syntax:
try code
Parameters:
code: Code
Return Value:
Exception Type

Alternative Syntax

Syntax:
args try code
Parameters:
args: Anything - passed arguments, will be put in _this variable inside the "code"
code: Code
Return Value:
Exception Type

Examples

Example 1:
try { throw "invalid argument" } catch { hint str _exception };
Example 2:
123 try { if (_this != 123) throw "invalid argument" } catch { hint str _exception };
Example 3:
try { if (a > b) throw "Error: some error"; // OK // the command argument is static } catch { hint str _exception; }; try { _someFunc = { // ... }; if (a > b) throw (call _someFunc); // NOT OK // the command argument is dynamic // _someFunc is called first to get the value regardless of (a > b) outcome } catch { hint str _exception; }; try { _someFunc = { // ... }; if (a > b) then {throw (call _someFunc)}; // OK // the command argument is dynamic // _someFunc is only called when (a > b) is true } catch { hint str _exception; };

Additional Information

See also:
Exception handling throw catch

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
Killzone_Kid - c
Posted on Jun 09, 2015 - 20:52 (UTC)
Do not expect this behave like Javascript try catch and ignore all errors. But it does have one useful behaviour. Normally when a runtime error occurs in SQF (unlike when there is compile error) it continues to execute till the end. But if the script is placed in try {} scope and throw is used upon error, the script immediately terminates, exits the try {} scope and enters catch {} scope. This way it is possible to process possible exceptions in civilised manner.