So what's the preferred Julia syntax to achieve what I meant here: julia> fmt = "%8.1e"; julia> @sprintf(fmt, 3.1415) ERROR: first or second argument must be a format string
On Sunday, April 13, 2014 1:31:57 PM UTC-7, John Myles White wrote: > > As far as the macro is concerned, the splat isn’t executed: it’s just > additional syntax that gets taken in as a whole expression. > > The contrast between how a function with splatting works and how a macro > with splatting works might be helpful: > > julia> function splat(a, b...) > println(a) > println(b) > return > end > splat (generic function with 2 methods) > > julia> splat(1, 2, 3) > 1 > (2,3) > > julia> splat(1, [2, 3]...) > 1 > (2,3) > > julia> macro splat(a, b...) > println(a) > println(b) > :() > end > > julia> @splat(1, 2, 3) > 1 > (2,3) > () > > julia> @splat(1, [2, 3]...) > 1 > (:([2,3]...),) > () > > > — John > > On Apr 13, 2014, at 1:20 PM, Jeff Waller <[email protected] <javascript:>> > wrote: > > > Likewise I am having problems with @sprintf > > > > Is this because @sprinf is macro? The shorthand of expanding a printf > with format the contents of an array is desirable. I would have expected > the ... operator to take an array of length 2 and turn it into 2 arguments. > > > > julia> X=[1 2] > > 1x2 Array{Int64,2}: > > 1 2 > > > > julia> @sprintf("%d%d",1,2) > > "12" > > > > julia> @sprintf("%d%d",X...) > > ERROR: @sprintf: wrong number of arguments > > > > julia> @sprintf("%d%d",(1,2)...) > > ERROR: @sprintf: wrong number of arguments > > > > julia> @sprintf("%d",X...) > > ERROR: error compiling anonymous: unsupported or misplaced > expression ... in function anonymous > > in sprint at io.jl:460 > > in sprint at io.jl:464 > > > > julia> macroexpand(quote @sprintf("%d%d",X...) end) > > :($(Expr(:error, ErrorException("@sprintf: wrong number of > arguments")))) > > > >
