[Newbies] Newbie: Error Checking in Dynamically typed Language

Mathieu mathk.sue at gmail.com
Sun Dec 10 14:16:07 UTC 2006


It's seem to me that is not really a dynamical typed problem but more a design problem.
If you want to specifiy to the user witch object you expected you should well name them. And make
unit test so your customer can understand(and you can also remember why).


stephane ducasse a écrit :
> Hi
> normally you will not do explicit check.
> We only test when this is really important.
>> Hi all,
>> This is my first time working with a dynamically typed environment and
>> my first instinct is to error check all arguments.
> No good instinct for dynamically typed :)
>> For example suppose I want to create an object to represent an octet
>> in an IP address (a number between 0 and 256) I would do something
>> like this:
>> Object subclass: #Octet
>>    instanceVariables: 'octetValue'
>>    ......
>> initialize
>>    super initialize.
>>    octetValue := 0.
>> setOctetValue: numBtw0And256
>>    octetValue = numBtw0And256        <-------Here's where I have a
>> problem
>> How do I know the numBtw0And256 is actually an integer between 0 and
>> 256 and not 'cat' or '3.14'?
>> Since I came from statically typed languages I feel like I writing a
>> whole bunch of error  checking code along the lines of ifIsInteger:
>> ... etc which doesn't seem to be in the spirit of Squeak.
>> What am I doing wrong?
> Just write your code and tests!
> Initialize well your state.
> Do only check if you absolutely want in your constructor?
>> Thanks
>> Deech

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