AbstractMyType or just MyType for abstract types?

smldis · August 6, 2017, 11:33am

Hello,
For the naming of an abstract type (MyType), should I use AbstractMyType or just MyType for abstract types?

Base is using the former, some packages are using the latter. I remember someone telling that once it was not possible to have MyType as abstract type name and MyType() as constructor or callable type.

A side note, if abstract types would be highlighted somehow in the editors some of the disadvantages would disappear.

Is there someone with a clear perspective on this subject?

mauro3 · August 6, 2017, 11:59am

I don’t think there is a rule, and it will depend on your case. I think if you work mostly with the concrete types then having a AbstractMyType is good and vice-versa.

Not always, e.g. Associative is an abstract type.

Also of note is the rename FloatingPoint → AbstractFloat, which may give you some hints with your decisions:

github.com/JuliaLang/julia

Rename abstract numeric types like FloatingPoint and Complex?

opened 01:40PM - 26 Aug 14 UTC

closed 01:18PM - 29 Apr 16 UTC

jiahao

decision breaking

We've seen empirical evidence that new users sometimes use abstract numeric type…s like `FloatingPoint` or `Complex` in lieu of concrete types like `Float64` and `Complex128`. The result is that users end up with slow code or even wrong code due to operations over variables with types like `Array{Complex,2}` or `Vector{FloatingPoint}`. (For example: [this comment](https://github.com/JuliaLang/julia/issues/4796#issuecomment-28459235) in #4796) The unintentional use of abstract numeric types seems especially prevalent with `FloatingPoint` or `Complex` which share common prefixes with concrete types. Other abstract numeric types like `Signed` or `Real` do not seem prone to accidental misuse to the same extent. Suggestions for new names? I'd propose something like `FloatingPointAbstract` or `AbstractFloatingPoint` to emphasize the abstract nature of the type. And perhaps something like `ComplexCartesian` instead of `Complex` to emphasize the canonical (real, imaginary) representation and to distinguish it from polar forms or other more esoteric representations.

juliohm · August 8, 2017, 5:27am

I am also questioning myself about this convention sometimes. Currently I am adopting the Abstract prefix to make this abstraction very explicit throughout the codebase and to help with auto-completion on my text editor.

However, as @mauro3 mentioned, if you are manipulating these abstract types all the time as your primary package types, then removing the prefix may save you some typing.

It is a matter of taste