Re: How to use Glib::Value?

[Kjell Ahlstedt <kjellahlstedt gmail com>]

Right now we're maintaining two parallel-installable versions of glibmm, 
the stable glibmm-2.4 ABI series with the latest release glibmm 2.58.0 
(git branch glibmm-2-58), and the new and very unstable glibmm-2.60 ABI 
with the latest release 2.59.1 (git branch master).

In the master branch we can change both API and ABI until the first 
stable release of gtk-4 and gtkmm-4.
In the glibmm-2-58 branch the usual restrictions apply: No API or ABI 
must be changed or removed. New API and ABI can be added only when (if) 
we release a glibmm 2.60.x version in the glibmm-2.4 ABI series.

Yes, I know these API and ABI version numbers are confusing. It's just 
the way it is right now in glibmm.
It means that in the master branch you can suggest just about anything 
you like. In the glibmm-2-58 branch we can't do very much, basically fix 
obvious bugs and improve documentation. If there will be a glibmm-2-60 
branch, branched from glibmm-2-58, API and ABI can be added there, but 
not changed or removed.

You're welcome to write one or two MRs if you like. An MR for the master 
branch is probably the easiest one. In the master branch there is no 
requirement that all code that uses glibmm must continue to work without 
modification and without recompilation.

I don't understand the point of renaming the present Glib::Value classes 
to Glib::Value_t and then write new Glib::Value classes that use 
Glib::Value_t. In the master branch Glib::Value_t seems unnecessary. All 
code can be put in modified Glib::Value classes. In glibmm-2-60 it would 
not be allowed, if the new Glib::Value classes break ABI or API, which 
they probably will.

On 2019-03-08 14:35, Pavlo Solntsev via gtkmm-list wrote:
> Thank you for clarification.
>
> This is what I did for my code.
>
> template<class T>
> class Column {
>         Glib::Value<T> data
>
> public:
>         Column(){
>                 data.init(data.get_value_type());
>         }
>         Column(const T &val):Column(){
>                 data.set(val);
>         }
>
>         void set_value(const T &val){
>                 data.set(val);
>         }
>
>         T get_value(void){
>                 return data.get();
>         }
>
> };
>
> Usage is very convenient:
> Column<Glib::ustring> mColumn;
>
> mColumn.get(); // get value
> mColumn.set("New string"); // Set value
>
> This is just a general idea and some parts are missed. Do you think the
> similar code can be incorporated to Glib::Value? For example. If we
> rename the current class Glib::Value to Glib::Value_t and remove from
> the public API, we can define a new class Glib::Value which will
> include Glib::Value_t in the way I showed above. This will remove extra
> step such as call Glib::Value<T>::init(...) method.
>
> Just a suggestion. I can prepare MR if the idea is valuable.
>
> Thanks.