- All Known Implementing Classes:
IEclipseContext. The result of the function must be derived purely
from the provided arguments and context objects, and must be free from
side-effects other than the function's return value. In particular, the
function must be idempotent - subsequent invocations of the same function
with the same inputs must produce the same result.
A common use for context functions is as a place holder for an object that
has not yet been created. These place holders can be stored as values in an
IEclipseContext, allowing the concrete value they represent to be
computed lazily only when requested.
Context functions can optionally be registered as OSGi services. Context
implementations may use such registered services to seed context instances
with initial values. Registering your context function as a service is a
signal that contexts are free to add an instance of your function to their
context automatically, using the key specified by the
SERVICE_CONTEXT_KEY service property.
Method SummaryModifier and TypeMethodDescriptionEvaluates the function based on the provided arguments and context to produce a consistent result.
SERVICE_NAMEstatic final String SERVICE_NAMEThe OSGi service name for a context function service. This name can be used to obtain instances of the service.
SERVICE_CONTEXT_KEYstatic final String SERVICE_CONTEXT_KEYAn OSGi service property used to indicate the context key this function should be registered in.
computeEvaluates the function based on the provided arguments and context to produce a consistent result.
context- The context in which to perform the value computation.
contextKey- The context key used to find this function; may be
nullsuch as if invoked directly.
- The concrete value. Implementations may return
IInjector.NOT_A_VALUEto cause lookup to continue up the context hierarchy.