When I am developing packages, I often come across the following problem. struct Step{T} end func(::Step{1}, x) = do something... func(::Step{2}, x) = do some different things... I am not sure should I use singleton types Type{Step{1}} and Type{Step{2}}, instead of singletons Step{1} and Step{2} …

Often the context suggests a preferred method: eg if the type is a container but is meaningful for some method without its contents (eg convert), or the contents are not relevant for some kind of information (Base.IteratorSize), or no value is available at some point (eg you are just creating an ins…

[image] Tamas_Papp: When in doubt, I would go for instances, not types. I agree, you never know when you want to add options to the type in the form of fields

[image] Tamas_Papp: Often the context suggests a preferred method: eg if the type is a container but is meaningful for some method without its contents (eg convert ), or the contents are not relevant for some kind of information ( Base.IteratorSize ), or no value is available at some point (eg y…

Yes, I suggested these as examples where using types makes more sense.

FWIW the style guide in the manual recommends using instances: https://docs.julialang.org/en/v1/manual/style-guide/#Avoid-confusion-about-whether-something-is-an-instance-or-a-type-1

Should I dispatch on singleton types or their instances?

General Usage

rdeits August 30, 2019, 12:30pm 6

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Should I dispatch on singleton types or their instances?

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