Exception handling: Difference between revisions

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In Armed Assault exception handling is an implemented system of special scripting commands ([[try]], [[catch]] and [[throw]]), which allows your scripts to create and to react to exceptions.
In {{arma1}} exception handling is an implemented system of special scripting commands ([[try]], [[catch]] and [[throw]]), which allows your scripts to create and to react to exceptions.


Standard construction is:
Standard construction is:
<sqf>
try
{
// code block that can throw exception
if (_name == "") then
{
throw "no name";
}
else
{
titleText [format ["Good morning, Captain %1.", _name], "PLAIN DOWN"];
sleep 1;
titleText [_name, "PLAIN DOWN"];
};
}
catch
{
// code block that processes an exception
if (_exception == "no name") then
{
hint "Name was not entered";
titleText ["And the name isn't", "PLAIN DOWN"];
};
};
</sqf>


try {
{{Feature|important|{{Name|arma}} scripting commands do '''not''' create SQF exceptions by themselves if they encounter an illegal situation, they throw a compilation exception (i.e. the here-described exception handling cannot be used for error trapping).
    //block, that can throw exception
    if (_name == "") then {
        throw "no name"
    } else {
        TitleText [format["Good morning, Captain %1.", _name], "PLAIN DOWN"]
        ~1
        TitleText [_name, "PLAIN DOWN"]
    }
}<br>
catch {
    //block, that processes an exception
    if (_exception == "no name") then {
        echo "Name wasn't entred"
        TitleText ["And the name isn't", "PLAIN DOWN"]
    }
}


'''Note:''' ArmA scripting commands do '''not''' create an exception by themselves if they encounter an illegal situation (i.e. you can't use the here described exception handling for error trapping.)
The following would therefore '''not''' create a catchable exception:
<sqf>
try
{
a = 1 / 0; // SQF error happens here already
}
catch
{
hint "illegal operation"; // useless
};
</sqf>
}}


The following would therefore '''not''' create a catchable exception:
<code>try {a=1/0;} catch {hint "illegal operation";}</code>


 
[[Category: Scripting Topics]]
[[Category: Scripting Topics|Exception Handling]]

Latest revision as of 00:14, 22 July 2022

In Armed Assault exception handling is an implemented system of special scripting commands (try, catch and throw), which allows your scripts to create and to react to exceptions.

Standard construction is:

try { // code block that can throw exception if (_name == "") then { throw "no name"; } else { titleText [format ["Good morning, Captain %1.", _name], "PLAIN DOWN"]; sleep 1; titleText [_name, "PLAIN DOWN"]; }; } catch { // code block that processes an exception if (_exception == "no name") then { hint "Name was not entered"; titleText ["And the name isn't", "PLAIN DOWN"]; }; };

Arma scripting commands do not create SQF exceptions by themselves if they encounter an illegal situation, they throw a compilation exception (i.e. the here-described exception handling cannot be used for error trapping).

The following would therefore not create a catchable exception:

try { a = 1 / 0; // SQF error happens here already } catch { hint "illegal operation"; // useless };