Re: [boost] [1.44] Beta progress?

Subject: Re: [boost] [1.44] Beta progress?
From: Robert Ramey (ramey_at_[hidden])
Date: 2010-07-27 15:15:42

Matthias Troyer wrote:

>> If you say that really need to know about each type I'm not
>> going to dispute it.  But I will say I'm not seeing it.
>>
>> I sort of expect to see something like:
>>
>> class mpi_oprimitive ... {
>>    mpioutputfunction m_out;
>>    template<typename T, std::size_t s>
>>    mpi_out{
>>        // uh-oh programming error - no mpi size
>>        BOOST_STATIC_ASSERT(0 == s);
>>    }
>>
>>    mpiout_int<int, 2>(int t){
>>        mpi_out(MPI_SHORT_INT(t)));
>>    }
>>    mpiout_int<int, 4>(int t){
>>        mpi_out(MPI_LONG_INT(t)));
>>    }
>>    ...?
>>    void save(int t){
>>        mpiout_int(t, sizeof(t));
>>    }
>>    void save(short int t){
>>        mpiout_int(t, sizeof(t));
>>    }
>>    void save(long int t){
>>        mpiout_int(t, sizeof(t));
>>    }
>>    ..?
>>
>>    mpiout_uint<int, 2>(unsigned int t){
>>        mpi_out(MPI_SHORT_INT(t)));
>>    }
>>    mpiout_uint<int, 4>(unsigned int t){
>>        mpi_out(MPI_LONG_INT(t)));
>>    }
>>    ...?
>>    void save(unsigned int t){
>>        mpiout_uint(t, sizeof(t));
>>    }
>>    void save(const unsigned short int t){
>>        mpiout_uint(t, sizeof(t));
>>    }
>>    void save(const unsigned long int t){
>>        mpiout_int(t, sizeof(t));
>>    }
>>    ..?
>>    }
>>    ...
>>
>> I'm not even suggesting this, I'm just explaining
>> why adding "more" to the documentation or
>> spec or whatever would have occurred to me.
>
> Unfortunately it is not as easy since an arbitrary number of
> datatypes can be created by the user, e.g. for pairs, structs,
> arrays, ... . Hence there is not a limited list of types but a
> general template, and thus no automatic conversion takes place.

Ahh but these aren't handled in the mpi_?primitive class but
rather in the mpi_archive class - assuming it were to follow
the pattern in text and binary archives.

here's what I envisioned when I factored the code in my
archives.

class text_archives
    template
    save_override(
        invoke code in oserialize
            if it's a primitive - redirect (eventually) to text_primitive
            if its an array - invoke array code
            if its an enum - invoke enum code
            if it's a pointer - invoke pionter code
            else
                invoke serialize code - this would handle all the types you 
mentin above - pairs, structs. etc.
...

That is ONLY types marked primitive and C++ primitives have to be considered 
here.
Since the types in questions are marked primitive and convertible to 
primitive, I believe
that ONLY C++ integer types have to be considered in the mpi_?primitive 
classes.

Looking at text_primitive and binary_primitive you can see this.  A couple
of types needed special handling.  The can be filtered out in either
the archive class or the primitive class.  But most types need no special
treatment.  A couple do - bool is rendered as a character, char is rendered
as a small binary number.  But mostly this gets handled transparently.
It also handles most of the hassle with different sizes for built-in types.

Robert Ramey

>
> Matthias
>
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