Thanks a lot!
On Wed, Jan 6, 2016 at 2:00 PM, Milan Bouchet-Valat <nalimi...@club.fr>
wrote:
> Le mercredi 06 janvier 2016 à 13:48 +0100, Michael Krabbe Borregaard a
> écrit :
> > Interesting. I come from R, and one of the main advantages I feel
> > Julia has is that I do not have to do any in-function testing of what
> > types of arguments the user has passed into the function, generating
> > error messages etc. In Julia, all of this is handled automatically if
> > I specify a function argument.
> Yes, that's a feature that I really appreciate too! When it is obvious
> that one is expecting e.g. a Number or an AbstractString, there's no
> reason not to restrict the type (both for correctness and
> documentation).
>
> > I would think the ideal way of doing it would be to specify a
> > function argument with a broad type (e.g. Number) that is meaningful
> > for all the operations in the function, and prevents the user from
> > e.g. passing in a string and getting a weird error message, or a bool
> > and getting something spurious. Unfortunately, most of my functions
> > do not take simple types, they take Vectors, and a Vector{Int} does
> > not inherit from a Vector{Number}! - meaning that the whole idea of
> > inheritance is a bit lost for me. I guess I can do foo{T <:
> > Number}(a::Vector{T}) but that goes very far from the easy non
> > -specifying format that you support.
> >
> > In short, I am really confused about how to use types well in Julia
> > functions - and I did read the style guide. Can you guide me a bit
> > more towards a good approach?
> You're hitting a property called type invariance. See
> http://docs.julialang.org/en/release-0.4/manual/types/#parametric-compo
> site-types
>
> There's nothing wrong with writing foo{T<:Number}(a::Vector{T}).
> That's the recommended way, though that it's a bit verbose (maybe a
> shorter syntax will be added at some point).
>
>
> Regards
>
>
> > Thanks
> >
> > On Wed, Jan 6, 2016 at 1:27 PM, James Gilbert <jgrgilb...@gmail.com>
> > wrote:
> > > You'd think, reading this forum, that the preferred style is to
> > > specify the type of function arguments. I think that's what feels
> > > right for people with experience in other languages. Specifying
> > > argument types doesn't necessarily improve speed, and harms the
> > > reusability of code.
> > >
>
