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Subject: Re: [boost] How do folks test serialization code?
From: Robert Ramey (ramey_at_[hidden])
Date: 2013-08-05 14:01:07

John Maddock wrote:
>>> I've just committed the code so you can try for yourself, but
>>> basically rather than storing a sequence of "limbs" (which may vary
>>> in size from one platform/compiler to another), it stores a sequence
>>> of bytes instead. The bytes are extracted using high level
>>> operations (shifts and bitmasks) so there's no issue with endianness
>>> etc.
>> As I said before - this shouldn't be necessary.
> Consider a 128-bit integer type, internally this could be:
> * Expressed as 8 16-bit integers (intmax_t=32 bits).
> * Expressed as 4 32-bit integers (intmax_t=64 bits).
> * Expressed as a single 128-bit (native) integer.
> How would you serialize from one format to a different one without
> breaking it down into "portably small" chunks?

Of course you have to define the 128 bit integer in terms
of some other types. But THOSE types should already be
portably serializable.

another way to deal with this is to work a at a more primitive
level. By marking the 128 integer type as "primitive" and
defining an output for output/input stream operarate -
text archives should "just work". Of course these
operators will have to be implemented with portability
in mind so the issue is moved to somewhere else. But
then one probably needs to define these operators in
any case so for text archives serialization comes for

for binary and portable binary archives, one might
need to specialize the serialization operators. For binary
archives there's not much if anything to do. For
portable binary archives, one might have to make
a minor specialization. The portable binary archive
includes code for handling endianness of arbitrarily
long integer types. (note that portable binary archive
isn't complete in anycase in that it doesn't handle
floating point types - a good GSOC project if
one wants one.)

So you've got a couple of ways of addressing this.

Robert Ramey

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