- All Known Implementing Classes:
public interface IContextFunctionA context function encapsulates evaluation of some code within an
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
All Methods Static Methods Instance Methods Abstract Methods Modifier and Type Method Description
compute(IEclipseContext context, String contextKey)Evaluates the function based on the provided arguments and context to produce a consistent result.
getRootContext(IEclipseContext context)Recursively looks up the root
IEclipseContextin the context hierarchy.
static final String SERVICE_NAMEThe OSGi service name for a context function service. This name can be used to obtain instances of the service.
Object compute(IEclipseContext context, String contextKey)Evaluates 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.