Re: [Boost-users] serialization::make_nvp parameters

Subject: Re: [Boost-users] serialization::make_nvp parameters
From: Robert Ramey (ramey_at_[hidden])
Date: 2009-09-08 13:35:06

I would not expect this to work.

const char* const_temp = temp.c_str( );

provides a cont char * - but this pointer is only temporary and becomes 
invalid when the function creating it returns.  Hence the run time error.

Assuming that dynamically assigning a tag name is a good idea (I'll reserver 
judgement on this for now), I don't think that nvp is the right vehicle to 
try to do this.  I would guess that you'd have to make your own "wrapper" 
which makes a copy of the "tag".  The nvp specifically avoids doing this for 
efficiency reasons

Robert Ramey

"Hammond, John (UK New Malden)" <John.Hammond2_at_[hidden]> wrote in 
message 
news:69E82C655BA624438EC192FB2D5B54DB023C76D1_at_GLKMS2100.GREENLNK.NET...
Hello,
I am hoping someone could answer a question I have regarding the 
make_nvp(..) function of the Serialization library.
I am attempting to serialize a number of objects within a loop, and the name 
of the name-value-pair is to be assigned dynamically depending on some 
values taken from within the object that is to be serialized. I am currently 
performing the actions below:
my_obj  = GetMyObj(..);
std::string temp = str( boost::format("x:%1% y:%2%") % _x % _y );
const char* const_temp = temp.c_str( );
ar & boost::serialization::make_nvp(const_temp, my_obj);

This code compiles but will cause an exception on make_nvp. As far as I can 
tell, I am providing the function with the const char* that it requires, so 
am very confused as to why it is not performing as expected.
Any help with this would be greatly appreciated.

John Hammond

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