Writing Classes to File

[icee]

In article <e3p2me$oee$1 at digitaldaemon.com>, Jeremy says...
>
>In article <Pine.LNX.4.64.0605082013370.2422 at bellevue.puremagic.com>, Brad
>Roberts says...
>>
>>On Mon, 8 May 2006, Jeremy wrote:
>>
>>> In article <e3o0d4$1tdc$1 at digitaldaemon.com>, Sean Kelly says...
>>> >
>>> >Jeremy wrote:
>>> >> Is there a way I can just write a whole class to a file?
>>> >> 
>>> >> For example, why can't I do:
>>> >> 
>>> >> file.writeExact(someClass, someClass.sizeof);
>>> >> 
>>> >> This seems to just write 4 bytes, which must be the pointer.
>>> >> 
>>> >> The compiler complains when I do this:
>>> >> 
>>> >> file.writeExact(*someClass, (*someClass).sizeof);
>>> >> 
>>> >> Saying that '*' is only used infront of pointers -- but aren't class always
>>> >> represented with pointers?
>>> >
>>> >They are, but I think they don't have the same semantics as pointers 
>>> >insofar as the type is concerned.  This is what inspired me to make the 
>>> >"isizeof" proposal a few weeks ago, as there's currently no way to get a 
>>> >class' size at compile-time.  However, you can get it a run-time via:
>>> >
>>> >someClass.classinfo.init.length
>>> >
>>> >
>>> >Sean
>>> 
>>> Interesting... so could this be done:
>>> 
>>> file.writeExact(someClass, someClass.classinfo.init.length);
>>> 
>>> to write the entire class to a file? (I'd like to do some zlib compression on it
>>> too :-D )
>>
>>Even with this, direct writing of a class like this will only work in the 
>>simplest of cases.  It won't dive into sub structures, for example, 
>>char[]'s.  Object serialization for the general case is a lot more 
>>complicated.
>>
>>Later,
>>Brad
>
>Hrm... So after I write the class, I should also write the char[]'s seperately
>with another write function. This shouldn't be too much of a problem... my class
>consists mostly of floats/ints/doubles
>
>


offset  contents  
0  pointer to vtable  
4  monitor  
8...  non-static members  

from the D abi def.

so you also write and read pointer to vtbl, is this safe enough? especially when
exchanging between different program?