Function Names
catch, catch ifSynopsis
catch/catch if (expression, condition expression) { statements } [ else { statements } ]Description
In case throw() has been called, all furhter code statements will be skipped until one of these functions are encountered.
catch will always give recover "frisbee" value issued with the throw() function, whereas
catch if will only catch the value if the "frisbee" value compared with the comparison expression returns true. Otherwise, the frisbee
continues flying, i.e. the code further below will be skipped, including the 'else' block if added.
Call as: procedure
Restrictions
Indirect parameter passing is disabled
OS differences
None
Parameter count
1 (catch), 2 (catch if)
Parameters
| No. | Type | Description |
|---|---|---|
| 1 code |
variable :string |
frisbee value caught The frisbee value issued with the throw() function call will be recovered here. |
| 2 code |
comparison expression :string |
Values to compare with Applicable to catch if: Catching the value and continuing normal execution will only happen if the thrown "frisbee"
value matches with the comparison expression.
This parameter is a piece of code typically found on the right-hand side of a comparison with '=' or '<>'. Single values,
ranges (e.g. 3..5), multiple values separated by commas are supported. For text comparison, wildcards are supported if the
string is of type softquoted string.
|
Examples
define procedure( foo, {{ value, numeral }} )
{
if (value[]== 1) return; // No throw with value 1
echo("Throw: ", value[] );
throw( value[] );
echo("This text does not appear");
}
for (i[] = 1, i[] <= 3, i[]++)
{
echo(new line, "Round ", i[],":");
foo( i[] );
catch if( x[], <>2 )
{
echo("'catch if': Successful catch: ", x[] );
}
else
{
echo("'catch if': Nothing thrown" );
}
catch ( x[] )
{
echo("'catch' : Successful catch: ", x[] );
}
else
{
echo("'catch' : Nothing thrown" );
}
}Output
Round 1:
'catch if': Nothing thrown
'catch' : Nothing thrown
Round 2:
Throw: 2
'catch' : Successful catch: 2
Round 3:
Throw: 3
'catch if': Successful catch: 3
'catch' : Nothing thrown