Today's Smalltalk Daily looks at using Exception Handlers in Smalltalk.

The Examples used in the screencast:

"simple exception handling"
answer := [4/0]
		on: ZeroDivide
		do: [:ex | ex returnWith: 0].

"a simple exception"
aString := 'This is a String'.
aString at: 3 put: $f.

"now do a retry"
[aString at: 3 put: $f]
	on: NoModificationError
	do: [:ex | aString beMutable.
		ex retry].
^aString

"Handle more than one"
content := [HttpClient new get: 'http://www.cincomsmalltalk.com']
		on: HttpException, OSErrorHolder peerFaultSignal, OSErrorHolder transferFaultSignal, OSErrorHolder operationStartedSignal
		do: [:ex | ex returnWith: nil].

"create the set of exceptions"
toHandle := ExceptionSet new.
toHandle 
	add: HttpException;
	add: OSErrorHolder peerFaultSignal;
	add: OSErrorHolder transferFaultSignal;
	add: OSErrorHolder operationStartedSignal.
^toHandle

To watch, click on the viewer below:

If you have trouble viewing that directly, you can click here to download the video directly

You can also watch it on YouTube:

Technorati Tags: exception handler, error handler, smalltalk