Re: [Boost-users] Max Boost Fusion tuple parameters

13 Jun 2013

      On 06/12/13 04:54, Igor R wrote:
...
...
I probably jumped to the conclusion that "template argument number"
meant "number of template instantiations".  Sorry for that mistake.
I guess "template argument number" means the maximum arity of any
template.  IOW, if "template argument number" was 5, then any
template taking over 5 arguments would cause the MSVC10/11
compiler to diagnose an error.  IOW:
tuple
would be OK, but:
tuple
would cause MSV10/11 to issue a compiler error.
Is that right?
Yes, right.
...
Also, I also read somewhere that MSVC had not yet implemented
variadic templates:
Variadic templates are implemented in the updated MSVC 11 toolchain
("Microsoft Visual C++ Compiler Nov 2012 CTP").
http://www.microsoft.com/en-us/download/details.aspx?id=35515
Thanks for the link.

Now with variadic templates, can a tuple with > 64 elements be
created?  IOW, would the following:

  template struct tuple;
  tuple*pt=0;

compile?

FWIW, I used Christopher's variadic fusion library to compile
a 300 element tuple.  It took a while, but it compiled.
Also, timing results showing the compile time vs tuple size
with gcc4.8 are:

TUPLE_SIZE= 10
1.97 0.19 2.14
TUPLE_SIZE= 50
2.45 0.16 2.59
TUPLE_SIZE= 100
3.49 0.32 3.90
TUPLE_SIZE= 200
7.90 0.57 8.85
TUPLE_SIZE= 300
15.93 0.96 17.09

The timing results were produce on ubuntu with:

TIME.cmd=time --format '%U %S %e'

I think this gives:
   user-time system-time elapsed-time

It also appears that when TUPLE_SIZE >=100,
compile time goes up linearly.

The code compiled was:

  typedef slim::vector
  < int_value< 0 >
  , int_value< 1 >
  , int_value< 2 >
  , int_value< 3 >
.
.
.
...
tuple_t;
int run(tuple_t const&a_tuple)
{
  int sum=0;
  sum+=slim::at_c< 0 >(a_tuple).value;
  sum+=slim::at_c< 1 >(a_tuple).value;
  sum+=slim::at_c< 2 >(a_tuple).value;
  sum+=slim::at_c< 3 >(a_tuple).value;
.
.
.
  sum+=slim::at_c< 49 >(a_tuple).value;
  return sum;
}

and was generated by the attached python file
with TUPLE_SIZE as the argument.

-regards,
Larry

Re: [Boost-users] Max Boost Fusion tuple parameters

Larry Evans