+1. A lot of smalltalk things seem to be this way. Has a default (sometimes throw error, sometimes return nil), but allows the client to override the default easily.
From: "Ramon Leon" ramon.leon@allresnet.com Reply-To: The general-purpose Squeak developers listsqueak-dev@lists.squeakfoundation.org To: "'The general-purpose Squeak developers list'"squeak-dev@lists.squeakfoundation.org Subject: RE: Way of indicating an error Date: Mon, 26 Feb 2007 09:09:58 -0700
Hi,
if a method should compute and return a value. If this method detects an error in its process what is the best way to indicate it:
- returning nil instead of the computed value
- raise a specific error
Bye
-- Damien Cassou
I like how detect works. If you don't pass a handler, raise an error
^#(John Doe) detect: [:each | each = 'Ramon'] => Error: Object is not in the collection
If you want to handle the error, don't catch it, make another method that takes the handler as an arg so the api is cleaner, so the client doesn't have to catch it.
^#(John Doe) detect: [:each | each = 'Ramon'] ifNone:['']
Then you can return nil via the handler if you like, or just handle the error some other way like returning an empty string, or don't pass a handler and let the exception propagate.
Ramon Leon http://onsmalltalk.com
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