please have a look at https://github.com/JuliaLang/julia/pull/6122 which looks like the way to go (once merged)
Cheers Tobi Am Montag, 8. Dezember 2014 20:18:18 UTC+1 schrieb Josh Langsfeld: > > On Monday, December 8, 2014 12:15:23 PM UTC-5, Utkarsh Upadhyay wrote: >> >> I have just tried playing with Julia and I find myself often copying >> `immutable` objects while changing just one field: >> >> function setX(pt::Point, x::Float64) >> # Only changing the `x` field >> return Point(x, pt.y, pt.z, pt.color, pt.collision, pt.foo, pt.bar); >> end >> >> Is there is any syntactical sugar to avoid having to write out all the >> other fields which are not changing (e.g. pt.y, pt.z, etc.) while creating >> a new object? >> Apart from making the function much easier to understand, this will also >> make it much less of a hassle to change fields on the type. >> >> Thanks. >> > > I played with it some more and this seems to work: > > defn = setdiff(names(Point), [:x]) > @eval Point(x, $([:(pt.$n) for n in defn]...)) > > Of course, this will only work for the x parameter which comes first in > the field list. I'm not sure how you might extend it to arguments in the > middle of the list, but maybe you can figure it out. >
