try: Difference between revisions

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m (Text replacement - "<code>([^<]*)\[\[([a-zA-Z][a-zA-Z0-9_]+)\]\]([^<]*) *<\/code>" to "<code>$1$2$3</code>")
m (Text replacement - "<sqf>([^↵][^<]*↵[^<]*)<\/sqf>" to "<sqf> $1 </sqf>")
 
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|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
{ /* block that can throw exception */ }
catch
catch
{ {{codecomment|/* block that processes the exception. Exception is described in the ''_exception'' variable */}} };</code>
{ /* block that processes the exception. Exception is described in the _exception variable */ };
</sqf>


|s1= [[try]] code
|s1= [[try]] code
Line 40: Line 42:
|r2= [[Exception handling|Exception Type]]
|r2= [[Exception handling|Exception Type]]


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


|x2= <code>123 try {if (_this != 123) throw "invalid argument"} catch {hint str _exception};</code>
|x2= <sqf>123 try { if (_this != 123) throw "invalid argument" } catch { hint str _exception };</sqf>


|x3= <code>try {
|x3= <sqf>
try {
if (a > b) throw "Error: some error"; // OK
if (a > b) throw "Error: some error"; // OK
// The command argument is static
// the command argument is static
} catch {
} catch {
hint str _exception;
hint str _exception;
Line 53: Line 56:
try {
try {
_someFunc = {
_someFunc = {
.....
// ...
};
};
if (a > b) [[throw]] ([[call]] _someFunc); // NOT OK
if (a > b) throw (call _someFunc); // NOT OK
// The command argument is dynamic
// the command argument is dynamic
// _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
// The command argument is dynamic
// the command argument is dynamic
// _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>
};
</sqf>


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


 
{{Note
<dl class="command_description">
|user= Killzone_Kid
 
|timestamp= 20150609205200
<dt></dt>
|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.
<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>

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.