Re: [boost] [serialization] Passing literals to oarchive

Subject: Re: [boost] [serialization] Passing literals to oarchive
From: Bjorn Reese (breese_at_[hidden])
Date: 2015-03-30 08:41:40

On 03/29/2015 05:35 PM, Robert Ramey wrote:
> Bjorn Reese wrote
>> On 03/27/2015 05:49 PM, Robert Ramey wrote:
>>
>>> In this case the problem is different.  A parameter value placed on the
>>> stack cannot be passed by "const T & t".  This syntax assumes and
>>> enforces
>>
>> Why not?
>
> It generates a compile time error when you pass an rvalue.

I am not sure I follow you. Are you saying that the following does not
compile?

   template <typename T> void foo(const T& t) {}

   int main()
   {
     foo(42);
     int x = 42;
     foo(x);
     return 0;
   }

> Since I wrote this, I've been considering it.  I looked at your patch.
> I would likely condition it on the type being a tracked or untracked
> type rather than being on a primitive type.

That is perfectly fine with me.

> the reason I would think that it's not a common case is the following:

The unit-tests for my own output archives checks that the encoding is
correct by feeding literal values into the archive. If I could pass
literal values to an oarchive, then it would look like this:

   archive << 1 << 0x0100 << 0x010000 << 0x0100000000LL;

followed by a check to verify that the archive has generated to correct
output.

However, currently I have to specify temporary variables (with odd
names) for the literal values, which leads to code like this:

   int alpha = 1;
   int bravo = 0x0100;
   int charlie = 0x010000;
   long long delta = 0x0100000000LL;
   archive << alpha << bravo << charlie << delta;

I have plenty of the above workarounds in my unit-tests.

> ar >> ?;  // what do we do with the result we're retrieving?

That is not what I am asking for, but you compare and skip the literal
values like iostream does.