GNU Smalltalk: Difference between revisions

The following code defines a class named Person. By deriving from Magnitude, it automatically defines all comparison methods except one (<codett>&lt;</codett>). With the addition of that one, <codett>asSortedCollection</codett> can sort by age. Note that we can override the way the object is printed/displayed (the default is to share the programmer-print and user-display representation) by overriding <codett>printOn:</codett>.

An exception is raised with a <codett>halt</codett> call:

An optional message can be added to the exception; there's also <codett>error:</codett> which raises a different kind of exception:

These are actually wrappers for the actual exception raising method, <codett>signal>:

Exceptions are handled by <code>on:do:</codett> blocks.