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Exception handling
From Axaptapedia
When execution a string of code, there is a risk that something may go wrong. Exception handling lets you handle system errors by your own code.
Contents
Try and Catch[edit]
If you are able to predict a block of code, where an exception will occur under certain circumstances, you can use the try command:
<xpp> try {
// Block of code that may fail
} catch (exception::error) {
// Do something about this error
} </xpp>
Retry[edit]
If you enter Retry in the catch block the try block is executes once more, but be carefull as this can result in a never-ending loop.
Catch enums[edit]
| Enum (exception::) | Description |
|---|---|
| Info | |
| Warning | |
| Deadlock | |
| Error | |
| Internal | |
| Break | |
| DDEerror | |
| Sequence | |
| Numeric | |
| CLRError | |
| CodeAccessSecurity | |
| UpdateConflict | |
| UpdateConflictNotRecovered |
Example[edit]
<xpp> static void TryCatchTest(Args _args) {
Map m = new Map(types::Integer, types::String); str s; int i; ;
m.insert(0,"Zero"); m.insert(1, "First"); m.insert(2, "Second"); m.insert(4, "Fourth");
for (i=0;i<4;i++)
{
try
{
s = m.lookup(i);
print s;
}
catch (exception::Error)
{
i++; // Try to solve the problem (This IS just an example!)
retry; // retry the statement.
}
}
pause;
} </xpp>
