Thanks a lot for the hint and for the useful code hack.
Let me elaborate a bit about multiple @printf in order to avoid
misunderstanding and explain the use case:
I was translating from Fortran
```Fortran
write(50,1001) mptr,level,mx
1001 format(i5,' grid_number',/,
& i5,' AMR_level',/,
& i5,' mx')
```
The 1st variant of translation with a big format string:
```julia
@printf(unit50,
"%5d grid_number\n%5d
AMR_level\n%5d mx\n",
mptr,level,mx)
```
i.e. is not very pretty-looking as the format string is too big.
In C it can be written as
```C
printf(unit50,
"%5d grid_number\n"
"%5d AMR_level\n"
"%5d mx\n",
mptr,level,mx);
```
due to consecutive tokens pasting.
Finally I gave up and just wrote:
```julia
@printf(unit50,"%5d grid_number\n",mptr)
@printf(unit50,"%5d AMR_level\n",level)
@printf(unit50,"%5d mx\n",mx)
```
Thanks,
Alexander
On Monday, February 3, 2014 7:39:04 AM UTC+4, Jake Bolewski wrote:
>
> I don't think you can do this as a macro, you want to use a function
> instead wrapping multiple @printf's as you stated.
>
> the behavior you are asking for is to partially evaluate the string
> function at compile time (hack)
>
> macro myprintf(args...)
> if length(args) == 0
> error("@myprintf: called with zero arguments")
> end
> if isa(args[1], String) || (isa(args[1], IO) && isa(args[1], String))
> :(@printf($(args...)))
> else
> local io, func, fargs
> if isa(args[1], Expr)
> io = :(Base.STDOUT)
> func = args[1].args[1]
> fargs = args[1].args[2:end]
> elseif (isa(args[1], IO) && isa(args[2], Expr))
> io = args[1].args[1]
> func = args[1].args[2]
> fargs = args[1].args[3:end]
> else
> error("better message here")
> end
> for i in 1:length(fargs)
> if isa(fargs[i], Symbol)
> fargs[i] = getfield(current_module(), fargs[i])
> end
> end
> fmt_string = apply(getfield(Base, func), fargs...)
> :(@printf($io, $fmt_string, $(args[2:end]...)))
> end
> end
>
> however this does not work at all with local scope.
>
> julia> a = "This is "
> "This is "
>
> julia> b = "a test: %d"
> "a test: %d"
>
> julia> @myprintf(string(a, b), 10)
> This is a test: 10
> julia> let a = "test1 ", b = "test2 %d"
> @myprintf(string(a, b), 10)
> end
> This is a test: 10
> julia>
>
>
> Best,
> Jake
>
> On Sunday, February 2, 2014 6:53:04 PM UTC-5, John Myles White wrote:
>>
>> Hi Alexander,
>>
>> I’m not aware of a way to do this, but would also like to know how to do
>> it.
>>
>> — John
>>
>> On Feb 2, 2014, at 5:52 AM, Alexander Samoilov <
>> [email protected]> wrote:
>>
>> > Hello,
>> >
>> > I have a format string - a "%Fmt" literal for @printf() and it is too
>> large, so would like to concatenate it from chunks,
>> > say using string("chunk 1 ", " chunk 2 ", " chunk 3 ")
>> >
>> > @printf() disallow to do it as requires a string literal, but string()
>> is a function and the produced string variable cannot be checked vs.
>> @printf() args.
>> >
>> > julia> @printf(string("abc ", " def ", " ggg "))
>> > ERROR: first or second argument must be a format string
>> >
>> > Looks this is intentionally to have an opportunity to check format
>> string vs. parameters (at least check number of args).
>> >
>> > BTW, C allows gluing of a few consecutive strings, e.g. "abc " " def "
>> " ggg " into one string literal, though it doesn't look very aesthetic.
>> >
>> > Is it possible for Julia to construct a format string somehow and feed
>> it to @printf() or this is impossible in principle
>> > and several invocations of @printf() should be used as workaround?
>> >
>> > Thanks,
>> > Alexander
>>
>>
