First, I believe I’ve seen this question discussed here before, but I cannot find it. My apologies if you do find it.
I’m starting a new project, and trying to figure out why IsResolved and/or ResolvedOn make more sense to me than Resolved. Obviously, when something is named “CompanyName” (for example), I’m fairly confident I’ll test it as a string. However, when I see “Resolved”, and I know the object it describes may not have a valid value for a resolution date, it bothers me that I have to inspect the type to determine how to test it: for undefined/null/etc. (as a date), or as a boolean value.
Is it reasonable to claim that Is and On typically do more than declare the variable type; they declare the intent? Or perhaps simply that it makes the code clearer for some other reason I’m not quite able to codify?
Arguing the other side, if I look at the type of Resolved, and see that it is a boolean, I will have my answer. Perhaps this is no different than knowing that I’ll need to inspect a “Feasibility” variable to determine if it is an int, enum, or something else. (Although perhaps just that means “Feasbility” would be a sub-optimal name also.) And regardless, in the case of “ResolvedOn”, I still have to inspect whether it is nullable to determine if I additionally need to inspect an “IsResolved” value. What is the point of the verbosity, encoding a second time in the variable name that which can be deduced from the type?
Please give me a hand understanding why Is[Property] and [Property]On make sense to me, although Hungarian in general does not. Or, explain why an exception like this wouldn’t make sense?
Note: I primarily work with SQL, C#, and JavaScript.
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First of all, most of the allergic reactions to Hungarian notation stems from the fact that consistent application tends to result in very unnatural looking names. Occasional uses of prefixes or suffixes that suggest a certain type should not be considered to be Hungarian notation unless the name looks very forced.
What you are doing by using “IsResolved” or “ResolvedOn” instead of “Resolved” is disambiguating what information is conveyed by the name (i.e. what is represented by a class or object of that name, what does a thus-named function return).
To take a few more examples:
- Company
- CompanyName
- Resolved
- IsResolved
- ResolvedOn
When reading code, “Resolved” would be the only one where I don’t have an idea what it would represent and I would need to look it up. Context makes a difference and I am not claiming I am always correct, but “Resolved” is the only name in that list where I would not be able to tell at a glance if it looks to be used correctly.
4
I’d say that neither of your examples actually involve hungarian notation, which is why you find them acceptable. blnResolved or dtResolved would be using hungarian notation. IsResolved and ResolvedOn are simply descriptive names. You could make IsResolved into HasBeenResolved if you like, but it’s considerably longer and will not convey any additional information.
That said, don’t let your dislike for hungarian notation get in the way of good names, DateResolved or ResolvedOnDate are again, just descriptive names. It just so happens that it includes what on some systems are an approximation of the data type — note that for TSQL 2000 it isn’t the exact data type as it doesn’t have a date datatype.
I’d say that Resolved is a boolean, as well as IsResolved. ResolvedOn could be a date.
However, one simply cannot depend on notation or name of a variable to determine its type, especially if one is going through someone else’s code. Imagine variables named in different language (we had an exchange student from Mexico, and she named all of her variables in Spanish). Also, there is a variable CompanyCode, for example. Can you tell whether it’s a string or an int?
2
I believe the reason you think Is[Xxxxxxx] makes sense to you is due to your proficiency with SQL. Microsoft SQL has several IsXxxxxxxxx functions that makes life very easy for its users.
Your exposure to Microsoft SQL’s IsXxxxxxxx type programming has shaped your thought process and you tend to lean toward using it outside of SQL. Why, because it does make sense. You probably question why other languages do not have similar built-in functions and you also probalby look to build similar IsXxxxxx functions when they are missing from the other languages you use.
I’m only speculating but your [Xxxxxxxx]On is probably just a natural progression of a similar thought to simplify properties that can either be On or Off.
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