Is something as simple as do the T, K and V parameterised types make sense versus mnemonics in Generics a hot item to talk about? You bet, people cannot seem to get enough of it.The crux of the issue here is do T, K, V, etc in examples like List<T>, IDictionary<K,V> make sense versus something like List<Item>, IDictionary<Key, Value>. Apparently both sides make seemingly valid arguments and from what I gather, its also a hot discussion topic within Microsoft. There have been examples that point out that c# is supposed to be easy to understand and not messy as shown in this example. But in the long discussion here are the main points in favour of descriptive names:
- You can tell at a glance what each type parameter is used for.
- As with method parameters, so with type parameters: descriptive names are useful and helpful and mean you have to memorise less.
- To dispel the mistaken notion that a type parameter is simply a placeholder that doesn’t “mean anything”.
- Saying of List<T>: “it’s a list of some type T” may work, but other similar situations don’t work (e.g. Point<T>)
- Even List<T> isn’t as simple as people think it is; “T” is never really OK.
- T, V, K etc. may (just) be OK for native English speakers, but is not OK for those whose first language is not English.
- If you choose the first letter of each word as your type parameter name (e.g. K, V), what if two or more words start with the same letter ?
- Using descriptive names reduces the incidence of name clashing where two or more “T”s mix in the same lexical space.
- You don’t have to look up what “T” means virtually every single time you come back to use a generic class, and you don’t have to bear it mind while you’re using the class (and why should you ?).
- The case for using of single letters gets worse as more type parameters are added to generic classes in the future.
- Using “T” leads you to then use “U” (as in the Converter delegate). “T” may stand for Type, but “U” doesn’t stand for anything. So the single-letter convention is inconsistent as well as unhelpful.
- The brain isn’t overloaded having to remember what “T” and “U” stand for in more complex situations where generic types are mixed (e.g. in List<T>’s ConvertAll method).
I personally don’t particularly care, though given a choice, I prefer the <T,K,V> but that is probably because what I am use to seeing. We of course will know the outcome of this when Whidbey ships. 🙂
