Re: [Engine-devel] [engine-devel] frontend builders proposal

----- Original Message ----- > From: "Tomas Jelinek&quot;&lt;tjelinek(a)redhat.com&gt; > To: engine-devel(a)ovirt.org > Sent: Friday, January 25, 2013 11:55:43 AM > Subject: [Engine-devel] [engine-devel] frontend builders proposal > > Hi All, > > as many of you may know, the way how the frontend and backend models > are built on frontend (uicommonweb project) is not really ideal. > Currently this logic is copy pasted over and over again to different > places where it is needed with minor changes to fulfill the specific > requirements. It is not only aesthetically problematic, but I recall > tons of bugs caused by introducing a new field and forgetting to add > it to every place it is used in GUI. > > Now, as there will be big changes in the VM/Template models > (http://www.ovirt.org/Features/Instance_Types), so the way how the > VM, Template, Pool and also the newly created Instance Types models > are being built has to be touched anyhow, it is a great opportunity > to rethink the way how we do it. > > I have created a simple infrastructure > (http://gerrit.ovirt.org/#/c/10874/) which could be used for it, and > a PoC patch which uses this infrastructure > (http://gerrit.ovirt.org/#/c/11354/). Please note that the PoC is > not really impressive in means of removing duplications, I wanted to > start with the simplest possibility. > > The principles behind the infrastructure: > - have small, well named, easy to understand and reuse builders > - this builders can be chained together or embedded to each other to > build the full resulting object (composite pattern) > - this builders can be asynchronous, and the next builder in the > chain has to be executed only when the current is completely done > > The structure: > - the base is an interface called Builder which has a method > build(source, destination, rest) > - the builder implementing this interface > + will get the source and destination objects > + copies whatever he wants from source to destination > + when done, executes build on the first element of the rest > + this may sound awkward, but this is the way how the async calls > can be "linearized" in a general way, not embedding anonymous > class into anonymous > class into anonymous class... as we do it today. > + for synchronous builders, there is a BaseSyncBuilder which > takes care of this boilerplate calling of next and exposes a > simple method > build(S source, D destination) > + to simplify the creating and running the chain of builders, there > is a BuilderExecutor class (can be created as sync or async) > > So, a simple example - even more simple than the PoC patch :) > > //create the first builder > class FirstLetterBuilder extends BaseSyncBuilder<String, > StringBuilder> { > @Override > protected void build(String source, StringBuilder destination) { > // copy the first letter to the destination > destination.append(source.charAt(0)); > } > } > > //create the second builder > class SecondLetterBuilder extends BaseSyncBuilder<String, > StringBuilder> { > @Override > protected void build(String source, StringBuilder destination) { > // copy the second letter to the destination > destination.append(source.charAt(1)); > } > } > > // usage > ... > // create the destination object > StringBuilder res = new StringBuilder(); > > // configure the executor with the two builders > BuilderExecutor<String, StringBuilder> executor = new > BuilderExecutor<String, StringBuilder>( > new FirstLetterBuilder(), > new SecondLetterBuilder() > ); > > // execute the builder chain ("ab" is the source, res the > destination) > executor.build("ab", res); > > // use the result > ... > > That's it. And the nice part is, that this FirstLetterBuilder and > SecondLetterBuilder can be reused anywhere or combined with any > other builders. > > Any comments on this will be more than welcome! great and really simplifies work and eliminate bugs resulted from copy/past code gave +1 Thanks Eli > Thank you, > Tomas > _______________________________________________ > Engine-devel mailing list > Engine-devel(a)ovirt.org > http://lists.ovirt.org/mailman/listinfo/engine-devel > _______________________________________________ Engine-devel mailing list Engine-devel(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel