Contexts are the groups into which rules are partitioned. The context
default-context
always exists. Contexts are defined by:
<context> ::=
(defcontext <context-name>
[:strategy <CRS>]
[:auto-return t | nil]
[:meta <meta-actions>])
[:documentation <doc-string>])
where
<context-name>
is a symbol,
<CRS>
is a conflict resolution strategy defaulting to
(priority recency order)
(see below). If
:auto-return
is set to
t
(the default) then when the context has no more rules to fire, control passes to the next context on the agenda, but if it is
nil
an error occurs (a rule in the context should have issued a
(return)
instruction explicitly). The
:meta
option is necessary only if the default behavior of the context is to be modified and is explained in Meta Rule Protocol. If
:documentation
is given, then
doc-string
should be a string and the value can be retrieved by calling the function
documentation
with doc-type
context
.
KnowledgeWorks and Prolog User Guide (Macintosh version) - 6 Dec 2011