Hi Jeff, Note that DatastoreServiceConfig exposes a withDefaults() method. FetchOptions has one too but it's package protected. We didn't expose it because FetchOptions isn't required for many low level datastore calls and we didn't see why users would want to create one if they didn't plan to adjust the offset, the limit, the prefetch size, etc. We didn't consider your use case though, and it makes perfect sense. Unless there's some other aspect of the Builder pattern that is getting in your way that you have explained, I think we could easily address your concern if we exposed FetchOptions.withDefaults(). Is that right?
Thanks, Max On Thu, Apr 1, 2010 at 3:07 AM, Jeff Schnitzer <[email protected]> wrote: > This is a genuine, heartfelt plea: The Builder pattern > (DatastoreServiceConfig, FetchOptions) makes code extra annoying when > layering an API on top of the low-level API. > > Let's say you are writing some code by hand that creates a > FetchOptions with a limit and an offset: > > FetchOptions opts = FetchOptions.Builder.withLimit(100).offset(20); > > Pretty straightforward when typing it out by hand, but the lack of > orthogonality between withLimit() and limit() is a PITA when you're > trying to automate the creation of a builder. The problem is, you > can't start with a "blank" FetchOptions. The result is we end up > writing lots of code like this: > > if (limit != null) > { > if (opts == null) > opts = FetchOptions.Builder.withLimit(limit); > else > opts = opts.limit(limit); > } > > This wouldn't be necessary if FetchOptions.Builder had a "create()" > method that would produce a blank FetchOptions. Or if FetchOptions > had a public constructor. Or if FetchOptions was an interface or even > a nonfinal class. > > I notice that DatastoreServiceConfig is following in the path of > FetchOptions. My initial reaction was Noooooo! :-) > > Thanks for listening, > Jeff > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine for Java" group. > To post to this group, send email to > [email protected]. > To unsubscribe from this group, send email to > [email protected]<google-appengine-java%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/google-appengine-java?hl=en. > > -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
