• "Tanel =?UTF-8?B?VGFnYXbDpGxpIg==?= <tanel58 hotmail.com> (7/7) Jul 13 2015 Does the standard library have a way to create a forward link
• Baz (20/27) Jul 14 2015 I have done a data binding system using properties in my D

"Tanel =?UTF-8?B?VGFnYXbDpGxpIg==?= <tanel58 hotmail.com> writes:

Does the standard library have a way to create a forward link 
between two variables of the same type?
One variable is the source and the other is the sink.
When the source variable is changed, the sink variable is too.
Changing the sink variable has no effect on the source variable.

I have already implemented it using std.signals and class 
templates(https://github.com/TheBlu/lockd/blob/master/source/engine.d), but is
there a better way, either in the standard library or a third party library?

"Baz" <bb.temp gmx.com> writes:

On Monday, 13 July 2015 at 22:07:11 UTC, Tanel Tagaväli wrote:
 Does the standard library have a way to create a forward link 
 between two variables of the same type?
 One variable is the source and the other is the sink.
 When the source variable is changed, the sink variable is too.
 Changing the sink variable has no effect on the source variable.

 I have already implemented it using std.signals and class 
 templates(https://github.com/TheBlu/lockd/blob/master/source/engine.d), but is
there a better way, either in the standard library or a third party library?

I have done a data binding system using properties in my D 
learning library.

(https://github.com/BBasile/iz/blob/master/import/iz/properties.d#L610)

The problem encountered with data binding is that there must be a 
signal.
So the most obvious way to do that is always more or less based 
on the observer pattern.

But there are other solutions:
- check a list of pointer in a thread or in a timer. (foreach 
target in targets...if target != source... ; Thread.sleep();)
- check a list of pointer when a particular message is found 
within a message queue.
(if messages.peek == msg.synchronize_bindings then foreach target 
in targets...)
- similarly, check the target "on idle", for example on windows 
when no message is dispatched then an idleEvent can be defined. 
This solution works fine with GUI programs.

A very D-ish way to do that would be to use UDA annotations to 
build the list of targets.