As mentioned in the other thread,
https://groups.google.com/d/msg/julia-users/hBbEGEopi0A/OX4ZEhFnBgAJ and
https://groups.google.com/d/msg/julia-users/hBbEGEopi0A/fKQcqDEVBgAJ, there
are concerns about generating new code for every single formatting string
used. I guess generally this won’t be much of an issue, but it could be.
Maybe write a package and see how much interest there is first?
— Mike
On Sunday, 27 September 2015 13:02:25 UTC+2, Daniel Carrera wrote:
>
> Hello,
>
> I made a trivial change to a some clever code by Tim Holy, and used it to
> make printf() and sprintf() function with the familiar syntax that we know
> from C/C++ (requires Julia 0.4):
>
>
> immutable FormatString{S} end
>
> FormatString(str::AbstractString) = FormatString{symbol(str)}
>
> @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, $(allargs...))
> end
> end
> @generated function Base.sprint{format}(::Type{FormatString{format}},
> args...)
> meta = Expr(:meta, :inline)
> fmt = string(format)
> allargs = [:(args[$d]) for d = 1:length(args)]
> quote
> @sprintf($fmt, $(allargs...))
> end
> end
>
> function printf(s::AbstractString, args...)
> print(FormatString(s), args...)
> end
> function sprintf(s::AbstractString, args...)
> print(FormatString(s), args...)
> end
>
>
> Could (or should) something like this be included in Julia by default? The
> first time you call printf() sprintf() with a new format string, the
> function call is slower than the @printf and @sprintf macros, but
> subsequent calls are just as fast:
>
> julia> @time @printf("%7d %7.2f", 220/7, 22/7)
> 31 3.14 0.024334 seconds (20.68 k allocations: 912.738 KB)
>
> julia> @time @printf("%7d %7.2f", 220/7, 22/7)
> 31 3.14 0.000102 seconds (30 allocations: 1.094 KB)
>
> julia>
>
> julia> fmt = "%6d %7.2f"
> "%6d %7.2f"
>
> julia> @time printf(fmt, 220/7, 22/7)
> 31 3.14 0.036154 seconds (36.81 k allocations: 1.675 MB)
>
> julia> @time printf(fmt, 220/7, 22/7)
> 31 3.14 0.000095 seconds (37 allocations: 1.250 KB)
>
>
>
> Daniel.
>
