@try_catch

macro bool? @try_catch(#v, #expr, fault expected_fault) @builtin

Check if an Optional expression evaluates to a fault. If so, return true if it is the
expected fault, the optional if it is unexpected, or false if there was no fault and
the assign happened.

This can be used in like this:

while (true)
{
char[] data;
// Read until end of file
if (@try_catch(data, load_line(), io::EOF)) break;
.. use data ..
}

In this example we read until we reach an EOF, which is expected. However, if we encounter some other
fault, we rethrow is. Without this macro, the code is instead written like:

while (true)
{
char[]? data;
data = load_line();
if (catch err = data)
{
if (err = io::EOF) break;
return err?
}
.. use data ..
}

Parameters