[Click] practices for singleton elements

[Eddie Kohler]

Hi Marco, sorry for the delay.

Yes, Router::attachment() can be used to enforce single instances, and for 
example that's how we make sure there's only one FromDevice per device. 
However, the Click practice has been to avoid true singleton elements when 
possible.  For example, a config can have multiple AddressInfo elements; Click 
combines their info, and also keeps AddressInfos local per compound element 
when appropriate.

In the end, just do what's easiest, and then make your element smarter as 
required.

Hope this helps.
Eddie


Marco Canini wrote:
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> Hello,
> 
> what are the current practices for singleton elements?
> is it up to the programmer to enforce a single instance or can click
> take care of guaranteeing a single instance is created?
> is Router.attachment() designed for this? (if not what is it for)
> cheers
> 
> 
> - --
> Marco Canini
> Ph.D. Candidate
> Department of Communication, Computer and System Sciences
> University of Genoa
> Via all'Opera Pia 13
> 16145 Genoa Italy
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