Hi Benjamin, Where is the code of the "working example"?
Cheers, Jonathan On Tue, 10 Apr 2018 at 12:04 Benjamin Rokseth <benjamin.roks...@deichman.no> wrote: > Community hackers, > > on hackfest I got introvertly enthusiastic about the concept of a Koha > Core, and > about time I shared some thoughts. > > Background: Deichman (Oslo Public Library) is heavily leaning on bleeding > edge Koha > development (REST, Objects, Auth, NCIP and such) and, like at least some > others, maintain > a lot of local patches to tweak Koha into our users needs. Some are > probably interesting to > Community, others not. Now to keep everything in sync with Community would > be amazing, > but not likely to happen anytime soon. > > Great work has been done on refactoring Koha (new namespace, Koha Objects > and REST api, etc.), > but we'd like to suggest one more - a Koha core. > The idea is simple: borrow from object oriented languages, java, or > actually more ruby, since > we're dealing with a dynamic language, use class/module inheritance and > method overrides. > Perl has the "use parent" concept which simplifies inheritance/subclassing > and allows for > nested overrides. > > As an example we refactored the current circulation in Koha, since this > for us is the core > functionality that we depend on and need to hook our local quirks on top > of. > An attempt to illustrate: > > +------------+ > | Core::Main | > +--^---------+ > | > +--+----------------+ > | Core::Prefs | > | Core::Exceptions | +-----------------------+ > | Core::Circulation <-----+------+---| Deichman::Circulation | > | ... | | | +---^-------------------+ > +-------------------+ | | | > | | | > +------------------+------+ +--------------------------+ > | Core::Circulation::SIP | |Deichman::Circulation::SIP| > +------------------------------------------------------------+ > | use parent qw( > | Deichman::Circulation > +----------------------+ Core::Circulation::SIP > | Core::Circulation::UI| ) > +----------------------+ > | > ~ > > * Core::Main is simply an empty class that act as a parent for any child, > including Core::Circulation. > * Core::Circulation has a constructor that takes koha objects item and > library, optionally patron > and sysprefs overrides. It can have accessors such as checkout, messages > and other things needed for > intra, SIP or whatever. It has methods Checkin, Checkout and Renew, > amongst others. > * then: Deichman::Circulation::SIP in this example is a local override > that inherits from parents > Deichman::Circulation and Core::Circulation::SIP > > now the beauty of this is that Deichman::Circulation::SIP can override > anything (even the constructor) > without touching any of the core code, and perl will traverse the > inheritance tree until it finds the > first matching constructor and method. > > Pros: > - simpler, more readable and more reusable code. > - local adaptations are easy to hande, and reusable for others > - the slight overhead of using blessed objects and inheritance is easily > gained by the fact that any > operation will only need fetching Koha objects once > (item,library,patron etc) instead of refetching > them numerous times spread across methods calls and loops > - way less db calls if done right, faster Koha > - no more C4::Context, hopefully > - systempreferences can be dramatically reduced, since most of them are > about overrides anyways > - can be done incrementally, replacing one functionality at a time > > cons: > - refactoring doesnt make end users happy (but needs to be done in any > case) > - a bit of work to keep templates happy > - requires a basic understanding of oop > > So to sum up: We already have a working example for circulation (though > not in production) > that we can demonstrate. It reimplements basically the entire > C4::Circulation, just some small > parts missing. So it can be done. > > But we'd love to hear second opinions from the community! We know the fear > for breaking changes, but > its neither scary or complicated to implement! > > Benjamin Rokseth > Oslo Public Library > _______________________________________________ > Koha-devel mailing list > Koha-devel@lists.koha-community.org > http://lists.koha-community.org/cgi-bin/mailman/listinfo/koha-devel > website : http://www.koha-community.org/ > git : http://git.koha-community.org/ > bugs : http://bugs.koha-community.org/ >
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