If this were Facebook, I would "Like" this :)
On Wednesday, September 23, 2015 at 9:34:27 AM UTC+8, Tim Holy wrote:
>
> At the risk of encouraging emacs users to "fix" the syntax with ctrl-T,
> I'd
> propose the following (apparently complete?) solution:
>
>
> immutable FormatString{S} end
>
> FormatString(str::AbstractString) = FormatString{symbol(str)}
>
> macro f_str(arg)
> :(FormatString{symbol($arg)})
> end
>
> @generated function Base.print{format}(::Type{FormatString{format}},
> args...)
> meta = Expr(:meta, :inline)
> fmt = string(format)
> allargs = [:(args[$d]) for d = 1:length(args)]
> quote
> @printf($fmt, $(allargs...))
> end
> end
>
>
>
> Demo:
> julia> print(f"%.3f", pi)
> 3.142
> julia> function foo(strs)
> for str in strs
> print(FormatString(str), pi)
> end
> end
> foo (generic function with 1 method)
>
> julia> strs = ("%.3f\n", "%.5f\n")
> ("%.3f\n","%.5f\n")
>
> julia> foo(strs)
> 3.142
> 3.14159
>
> julia> @time 1 # just to warm up @time
> 0.000004 seconds (148 allocations: 10.151 KB)
> 1
>
> julia> @time foo(strs)
> 3.142
> 3.14159
> 0.000106 seconds (18 allocations: 704 bytes)
>
>
> Nice that we get to re-use the macro that Stefan worked so hard on!
>
> Best,
> --Tim
>
