Re: dconf

[Ryan Lortie <desrt desrt ca>]

Hi Ronald

Ronald S. Bultje wrote:
>                                            what is GVariant, how does
> it relate to GValue, will it deprecate GValue and if so, why is it not
> possible to just fix GValue instead? It's not in your email which I am
> responding to, and it's not in the email which announces the existence
> of GVariant either.

GVariant and GValue have two very different goals.

A GValue is designed to hold values that will be passed around inside of 
a single process.  Things inside of GValues have GTypes.  They can 
contain pointers.  They are not generally serialisable and therefore 
cannot, in the general case, be sent between processes.  The GType 
system is shallow in the sense that only the toplevel type is given. 
For example, you can have G_TYPE_HASH_TABLE, but not "hash table that 
maps strings to pairs of strings and integers".

A GVariant is exactly equal to what can be sent over DBus -- and in the 
most direct way.  It is exactly the data as it will be sent: no 
additional encoding required.  A GVariant has a completely specified 
type.  You don't just say "array", but you specify the entire type in 
the same way that you specify DBus "signatures": an array of pairs of 
strings and integers would be "a(si)".  A GVariant (being by definition 
something that can be sent over the bus) can not contain pointers.

GVariant can not possibly replace GValue for most of the things that we 
currently use it for so there is no intention that GValue will be 
deprecated by it.  They solve two different problems.

Thanks for the question :)

Cheers