try_call

Safely call a function that may fail (i.e. that may throw an exception).

Accepts nullary unit-typed function references, i.e. references to functions of type () -> unit.

Exceptions thrown during the call are caught and logged with a stack trace.

Changes to the database that occur during the call are rolled back when an exception is thrown.

Examples:

function fails(): unit {
    list<integer>()[1]; // out of bounds
}
function succeeds(): unit {}
try_call(fails(*)) // logs an out of bounds exception message and returns false
try_call(succeeds(*)) // logs nothing, returns true

Parameters

Safely call a function that may fail (i.e. that may throw an exception).

Accepts nullary function references, i.e. references to functions of type () -> T, and returns T?, i.e. the return value of the reference function, or null.

Exceptions thrown during the call are caught and logged with a stack trace.

Changes to the database that occur during the call are rolled back when an exception is thrown.

Examples:

function fails(): integer {
    return list<integer>()[1]; // out of bounds
}
function succeeds(): unit { return 0; }
try_call(fails(*)) // logs an out of bounds exception message and returns null
try_call(succeeds(*)) // logs nothing, returns 0

Parameters

Safely call a function that may fail (i.e. that may throw an exception).

Accepts nullary function references, i.e. references to functions of type () -> T, and a default value to return if the call fails.

Exceptions thrown during the call are caught and logged with a stack trace.

Changes to the database that occur during the call are rolled back when an exception is thrown.

Examples:

function fails(): integer {
    return list<integer>()[1]; // out of bounds
}
function succeeds(): unit { return 0; }
try_call(fails(*), 17) // logs an out of bounds exception message and returns 17
try_call(succeeds(*), 17) // logs nothing, returns 0

Parameters