[Boost-users] Re: Tuples and stringstream

From: CodeLogic (codelogic_at_[hidden])
Date: 2005-04-11 11:57:58

> You can't create a tuple of stringstreams because basic_ios, which is a base
> class of stringstream, is non copyable. You should be able to create a tuple of
> references to stringstreams, though.

I see, my intention is to create tuples consisting of strings (strings 
or stringstream is immaterial for me, I used stringstream since they 
support io streams and I thought they would be more compatible when 
streaming tuples) and basically have the capability of streaming it in 
and out of a file.

>>fstream fin(filename.c_str(), ios_base::in);
>>tuple<stringstream, stringstream, stringstream, stringstream> test;
>>fin>>test;
> 
> 
> It's not clear what you're trying to do do here. If I saw this code in
> isolation, I'd guess you were trying to deserialize a tuple containing three
> strings.

This is my attempt of streaming a tuple from a file into the data 
struct. Maybe my code is incorrect :) ?

> Do you mean you want to store and retrieve a tuple<sting, string, string,
> string, ...>? You can't use operator>> for this, since it will use whitespace as
> a separator, in addition to being sensitive to istream field widths.

If the whitespace factor is the only drawback, I can work around it by 
replacing whitespaces (which I actually doubt I will have in my strings) 
with some other character like an '_'. If there are no whitespaces 
should this work as expected?

> You might try Boost.Serialization, although since I haven't used this library
> yet I don't know whether there is support for serializing tuples or whether you
> have to do it yourself. A simpler way would simply be to write the string to a
> file separated by a character which you know won't appear in any of the strings,
> if there is such a character.

 From what I read in the tuples documentation, tuples supports streaming 
out of the box:

http://www.boost.org/libs/tuple/doc/tuple_users_guide.html#streaming

I figured as long as I use fields that themselves supports streams (like 
stringstream), it should work fine.

But however, in the end, what I need is the ability to save tuples 
(consisting of strings and assuming there are no white spaces within 
each string) into a file and reload it when necessary.

Thanks a lot for your response !

CodeLogic.