serialization library

[Bill Baxter]

Walter Bright wrote:
> Bill Baxter wrote:
>> How do you fix it?  Very simple really.  Just store the file as a 
>> series of chunks with fixed length headers, and each header contains 
>> the length of the data in that chunk.  If you get a chunk header with 
>> a tag you don't understand, just ignore it.  A particular chunk can 
>> have sub-chunks too.
> 
> Evolution of a file format:
> 
> 1.0: Just spew the struct contents out into a file using something like 
> fwrite().
> 
> 2.0: Oops! Need to update 1.0 and retain backwards compatibility. 
> Solution: 2.0 files put out 'illegal' values into the 1.0 format to 
> signal it's a 2.0 file.
> 
> 3.0: Doh! Find another set of illegal 2.0 values. This time, get smarter 
> and have another field with a version number in it.
> 
> 4.0: Get smart and implement your suggestion, so you can have both 
> backwards and *forwards* compatibility.
> 
> Think I'm joking? Just look at a few! Everyone learns this the hard way.

I guess I'm no exception.  ;-)  I've been through the 4 step program a 
few times myself.

> Me, if practical, I like file formats to be in ascii so I can examine 
> them easily to see if they're working right.

That is one thing I do like about boost::serialization.  With basically 
one line of code I can switch between xml serialization and binary 
serialization.  Only thing I didn't like was I couldn't figure out how 
to keep some things binary.

--bb