@ Jameson (and Tim) good points. Thank you both for correcting me on that.
On Saturday, September 12, 2015 at 6:55:12 AM UTC-7, Jameson wrote: > > Accessing T.parameters is almost always completely wrong. (except for > TupleType: see https://github.com/JuliaLang/julia/pull/11547 for example) > > For example, I've posted on a similar question previously: > https://groups.google.com/d/msg/julia-users/Khe1Eh-K6i0/kxvj3day77AJ > > And I've written some example code of to show an example of solving this > for for one particular common case: > https://groups.google.com/d/msg/julia-users/NRBWq030YRE/OMIyXirmbgsJ > > > I'm not convinced it's more Julian to use such a helper function, since > it will needlessly compile a different method for each distinct set of > parameters. > > It's definitely more Julian to go this route. The helper function would be > inlined anyways, so there's essentially no overhead to this approach. > > > On Fri, Sep 11, 2015 at 4:10 PM Mauro <[email protected] <javascript:>> > wrote: > >> The interface Matt is prototyping for Tuple{}'s >> https://github.com/mbauman/Tuples.jl >> could (should?) be expanded for any type-parameters. (Or does it already >> work?) >> >> On Fri, 2015-09-11 at 21:54, David Gold <[email protected] >> <javascript:>> wrote: >> > I'm not convinced it's more Julian to use such a helper function, since >> it >> > will needlessly compile a different method for each distinct set of >> > parameters. Directly accessing the `parameter` field of the type in >> > question avoids this. >> > >> > On Friday, September 11, 2015 at 12:30:16 PM UTC-7, Josh Langsfeld >> wrote: >> >> >> >> You can access the 'parameters' field of a type instance object. But >> the >> >> standard Julian way to get type parameters is to just define a helper >> >> function: >> >> >> >> typeparams{A,B}(::Type{T{A,B}}) = A,B >> >> >> >> On Friday, September 11, 2015 at 3:20:17 PM UTC-4, Erik Schnetter >> wrote: >> >>> >> >>> Is there a function in Julia that allows accessing the parameters of a >> >>> type? >> >>> >> >>> For example, if I have >> >>> >> >>> type T{A,B} end >> >>> >> >>> then I'd like a way to convert `T{Int, Char}` to `(Int, Char)`. >> >>> >> >>> In other words, is there a way to get at the contents of `DataType` >> >>> objects? >> >>> >> >>> Thanks, >> >>> -erik >> >>> >> >>> -- >> >>> Erik Schnetter <[email protected]> >> >>> http://www.perimeterinstitute.ca/personal/eschnetter/ >> >>> >> >> >> >>
