diff options
Diffstat (limited to 'erts/doc')
| -rw-r--r-- | erts/doc/src/erlang.xml | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml index d6fe585c8d..fde04504c8 100644 --- a/erts/doc/src/erlang.xml +++ b/erts/doc/src/erlang.xml @@ -2613,6 +2613,48 @@ os_prompt% </pre> </func> <func> + <name name="match_spec_test" arity="3"/> + <fsummary>Test that a match specification works</fsummary> + <desc> + <p> + This function is a utility to test a match_spec used in calls to + <seealso marker="stdlib:ets#select/2">ets:select/2</seealso> and + <seealso marker="#trace_pattern/3">erlang:trace_pattern/3</seealso>. + The function both tests MatchSpec for "syntactic" correctness and + runs the match_spec against the object. If the match_spec contains + errors, the tuple {error, Errors} is returned where Errors is a list + of natural language descriptions of what was wrong with the match_spec. + </p> + <p> + If the <c><anno>Type</anno></c> is <c>table</c> the object to match + against should be a tuple. The function then returns + {ok,Result,[],Warnings} where Result is what would have been the + result in a real ets:select/2 call or false if the match_spec does + not match the object tuple. + </p> + + <p> + If <c><anno>Type</anno></c> is <c>trace</c> the object to match + against should be a list. The function returns + {ok, Result, Flags, Warnings} where Result is <c>true</c> if a trace + message should be emitted, <c>false</c> if a trace message should not + be emitted or the message term to be appended to the trace message. + Flags is a list containing all the trace flags that will be enabled, + at the moment this is only <c>return_trace</c>. + </p> + + <p> + This is a useful debugging and test tool, especially when writing complicated + match specifications. + </p> + <p> + See also + <seealso marker="stdlib:ets#test_ms/2">ets:test_ms/2</seealso>. + </p> + </desc> + </func> + + <func> <name name="max" arity="2"/> <fsummary>Returns the largest of two terms.</fsummary> <desc> |