try: Difference between revisions

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m (Text replacement - "\[\[Category:[ _]?Scripting[ _]Commands[ _]Arma[ _]2(\|.*)?\]\]" to "{{GameCategory|arma2|Scripting Commands}}")
m (Text replacement - "<sqf>([^↵][^<]*↵[^<]*)<\/sqf>" to "<sqf> $1 </sqf>")
 
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{{Command
{{RV|type=command


|game1= arma1
|game1= arma1
|version1= 1.00
|game2= arma2
|version2= 1.00
|game3= arma2oa
|version3= 1.50
|game4= tkoh
|version4= 1.00


|version1= 1.00
|game5= arma3
|version5= 0.50


|gr1= Program Flow |GROUP1=
|gr1= Program Flow


|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:
|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:
<code>[[try]]
<sqf>
{ {{codecomment|/* block that can throw exception */}} }
try
[[catch]]
{ /* block that can throw exception */ }
{ {{codecomment|/* block that processes the exception. Exception is described in the ''_exception'' variable */}} };</code> |DESCRIPTION=
catch
____________________________________________________________________________________________
{ /* block that processes the exception. Exception is described in the _exception variable */ };
</sqf>


|s1= [[try]] code |SYNTAX=
|s1= [[try]] code


|p1= code: [[Code]] |PARAMETER1=
|p1= code: [[Code]]


|r1= [[Exception handling|Exception Type]] |RETURNVALUE=
|r1= [[Exception handling|Exception Type]]
____________________________________________________________________________________________


| s2= args [[try]] code {{since|arma3|1.53.133045|y}} |SYNTAX2=
|s2= args [[try]] code


|p21= args: [[Anything]] - passed arguments, will be put in ''_this'' variable inside the "code" |PARAMETER21=
|s2since= arma3 1.54


|p22= code: [[Code]] |PARAMETER22=
|p21= args: [[Anything]] - passed arguments, will be put in ''_this'' variable inside the "code"


| r2= [[Exception handling|Exception Type]] |RETURNVALUE2=
|p22= code: [[Code]]


|r2= [[Exception handling|Exception Type]]


|x1= <code>[[try]] {[[throw]] "invalid argument"} [[catch]] {[[hint]] [[str]] _exception};</code> |EXAMPLE1=
|x1= <sqf>try { throw "invalid argument" } catch { hint str _exception };</sqf>


|x2= {{since|arma3|1.53.133045}}: <code>123 [[try]] {[[if]] (_this != 123) [[throw]] "invalid argument"} [[catch]] {[[hint]] [[str]] _exception};</code> |EXAMPLE2=
|x2= <sqf>123 try { if (_this != 123) throw "invalid argument" } catch { hint str _exception };</sqf>


|x3= The correct usage of shorthand alt syntax: <code>[[try]] {
|x3= <sqf>
[[if]] (a > b) [[throw]] "Error: some error"; {{cc|OK}}
try {
{{cc|The command argument is static}}
if (a > b) throw "Error: some error"; // OK
} [[catch]] {
// the command argument is static
[[hint]] [[str]] _exception;
} catch {
hint str _exception;
};
};


[[try]] {
try {
_someFunc = {
_someFunc = {
.....
// ...
};
};
[[if]] (a > b) [[throw]] ([[call]] _someFunc); {{cc|NOT OK}}
if (a > b) throw (call _someFunc); // NOT OK
{{cc|The command argument is dynamic}}
// the command argument is dynamic
{{cc|_someFunc is called first to get the value regardless of (a > b) outcome}}
// _someFunc is called first to get the value regardless of (a > b) outcome
} [[catch]] {
} catch {
[[hint]] [[str]] _exception;
hint str _exception;
};
};


[[try]] {
try {
_someFunc = {
_someFunc = {
.....
// ...
};
};
[[if]] (a > b) [[then]] {[[throw]] ([[call]] _someFunc)}; /// OK
if (a > b) then {throw (call _someFunc)}; // OK
{{cc|The command argument is dynamic}}
// the command argument is dynamic
{{cc|_someFunc is only called when (a > b) is [[true]]}}
// _someFunc is only called when (a > b) is true
} [[catch]] {
} catch {
[[hint]] [[str]] _exception;
hint str _exception;
};</code> |EXAMPLE3=
};
</sqf>


|seealso= [[Exception handling]], [[throw]], [[catch]]
|seealso= [[Exception handling]] [[throw]] [[catch]]
}}
}}


<h3 style="display:none">Notes</h3>
{{Note
<dl class="command_description">
|user= Killzone_Kid
<!-- Note Section BEGIN -->
|timestamp= 20150609205200
 
|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.
<!-- Note Section END -->
}}
</dl>
 
<h3 style="display:none">Bottom Section</h3>
[[Category:Scripting Commands|{{uc:{{PAGENAME}}}}]]
{{GameCategory|arma1|Scripting Commands}}
{{GameCategory|arma2|Scripting Commands}}
{{GameCategory|arma3|Scripting Commands}}
[[Category:Scripting Commands Take On Helicopters|{{uc:{{PAGENAME}}}}]]
 
 
<!-- CONTINUE Notes -->
<dl class="command_description">
<dd class="notedate">Posted on June 9, 2015 - 20:52 (UTC)</dd>
<dt class="note">[[User:Killzone Kid|Killzone Kid]]</dt>
<dd class="note">
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.  
</dd>
</dl>
<!-- DISCONTINUE Notes -->

Latest revision as of 19:43, 3 September 2024

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.