Tuesday 24 June 2008
Specific Data Types Avoid Primitives Confusion
An interesting confusion occured today at work one the interpretation of a method parameter named something like 'widgetPercentage'. One developer took 5% as being 0.05 and the original author expected 5% to 5.0. My first thought is that we are missing a 'Percentage' type to remove this ambiguity. But, this would require a constuctor that took a percentage as a sting like 'Percentage("5%")'. Seems fine, but both an example of my loathing of such strings and the lack of use of strong types. I do 'feel' that a strong type could have avoided the problem here.
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2 comments:
Clarity on construction of an object is interesting area because at first and often as a discussion topic it seems so easy.
I was reading the .NET Framework book recently and they had and interesting point on not passing in booleans to set the state of a class. Instead suggesting enums can be more clear.
http://msdn.microsoft.com/en-us/library/ms229039.aspx
For example
string.Compare("Dave", "dave", true)
This would be better.
string.Compare("Dave", "dave", Compare.CaseSensitive)
So in dragging this back to your example would a named constructor or even an exception in the constructor of the class that through on an unlikely decimal value have been useful?
Hi James,
The thing is that I think it is reasonable for some to consider 0.1 as 10% while others may interpret it as 0.1%. So a constructor taking a decimal or double not (alone) seem useful.
But, your suggestion of an exception would have worked in this case. 0.05 did result in 0.05% which, within the context was unreasonably low. Hmmm ... I want an oportunity to try it out.
Rob
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