Hey all, There seems to be a lot of confusion over what the design of the Switcher code wise is supposed to look like.
For months now, I've been toying around with a fix to bug 1060887, which basically is a wart in our build process, which causes several files to be re-generated for "testing" purposes. This causes build times to be much longer than they should be, and makes the switcher code very fragile because it is easy to break the script. I spoke with Stephen about a preferred design for the major classes such as the switcher. I was informed it should look something like this: NVI for the class that other classes talk to -> Which takes a function object that creates -> -> An object which implements the virtual interface of that class -> The non-virtual API calls delegate to the implementation instance among virtual calls to get to the implementation. However, this review went in the other day that changed that somewhat: http://bazaar.launchpad.net/~unity-team/unity/trunk/revision/3079 The result is that now the NVI class (eg switcher::Controller) has logic built in, and some of the methods are now nonvirtual. I understand the desire to simplify the design somewhat, but it actually makes it less testable in the long run. It is very important for work down the road on bug 1060887 that all the switcher controller and view methods be virtual, so that they can be replaced with mocks or stubs at runtime later. Having the tests depend on the behaviour of the external class not-under-test is very bad because it creates coupling between the behaviour of the external class and the test itself. The test setup/teardown/verification conditions need to be updated every time the external class not under test is updated in a way that might affect the test. An annoying side-effect of all of this is that I need to rewrite several bits of code later in my pipeline of changes to accommodate revision 3079. I'd like some clarification on what the preferred switcher design is actually meant to be. Do we want to strictly have the NVI classes delegate to their implementations? Or are we accepting business logic inside of our NVI classes where those functions are not virtual. Best Regards, Sam -- Sam Spilsbury -- Mailing list: https://launchpad.net/~unity-dev Post to : [email protected] Unsubscribe : https://launchpad.net/~unity-dev More help : https://help.launchpad.net/ListHelp
