Re: Serialization

From:
"Daniel T." <daniel_t@earthlink.net>
Newsgroups:
comp.lang.c++
Date:
Thu, 04 Nov 2010 20:12:54 -0400
Message-ID:
<daniel_t-6053B4.20125404112010@70-3-168-216.pools.spcsdns.net>
In article <m1tyjxj8w7.fsf@ip1-201.halifax.rwth-aachen.de>,
 Andrea Crotti <andrea.crotti.0@gmail.com> wrote:

I'm doing a very complicated structure for serialize/deserialize
objects, in short I have this abstract class

--8<---------------cut here---------------start------------->8---
#ifndef STREAMABLE_H
#define STREAMABLE_H

#include "Stream.hpp"

template <typename T>
class Serializable
{
public:
    Serializable() {}
    virtual Stream toStream() = 0;
    // used to parse the given stream and create the object
    virtual T parseStream(const Stream&) = 0;
};

#endif /* STREAMABLE_H */
--8<---------------cut here---------------end--------------->8---

and all the objects that want to bea able to create a stream and parse
it have to overload it.

Now 2 problems:
- the definition of the classes is something like
  class PadNodeID : public Serializable<PadNodeID>
  
  so the template parameter is always the class itself, maybe is it
  possible to avoid it?

- the "parseStream" function doesn't really make sense to be called from
  one object, since it's supposed to create one.
  But making it static and virtual doens't work, so how should I declare
  it in such a way that I can do.

--8<---------------cut here---------------start------------->8---
  Type t = Type::parseStream(st);
--8<---------------cut here---------------end--------------->8---

Thanks again,
Andrea


The code you posted above doesn't work. Type::parseStream(const Stream&)
cannot be called without an object.

I suggest you take your cue from the stream library...

class Stream { };
class Type { };

void readFrom(Stream& s, Type& t);
void writeTo(Stream& s, const Type& t);

void fn(Stream& st) {
   Type t;
   readFrom(st, t);
}

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