Labs/Ubiquity/Writing Noun Types: Difference between revisions

Ubiquity has a caching feature which allows it to remember the suggestions that a noun type gave for a particular input. The tricky part of this caching is in deciding when to flush the cached results for each noun type. The length of time that a noun types results remain accurate can differ greatly depending on the nature of the noun type. For instance, a noun type based on your open tabs may only remain accurate for a few seconds, while a noun type for known street addresses will probably remain accurate for at least weeks/months, and a noun type that is strictly regex based will be accurate forever. There are two ways for a noun type to declare when it should be flushed: the cacheTime property and and the registerCacheObserver method.

By default, a noun types results will be cached for one day. However, the user can specify a different duration for the cache by adding the cacheTime property to their noun type with some integer value that represents the length of time to keep results cached in seconds. A cacheTime of 0 will result in no caching, while a cacheTime of -1 will result in the results being cached forever.

While the cacheTime property allows noun types to specify a fixed amount of time between flushings of the cache, for some noun types it makes more sense to have the cache flushed on certain events. For example, noun_type_tab flushes it's cache every time a new tab is opened or an old tab is closed. In order to register observers for flushing, simply add the registerCacheObserver property to your noun type. This property should be a function which takes a single argument that is a flush function. You can call this flush function anytime you want to flush the cache of this noun type.