This section is a reference to the debugger interaction predicates. A more use-oriented overview of the debugger is in section 2.9.
If you have installed XPCE, you can use the graphical front-end of the tracer. This front-end is installed using the predicate guitracer/0.
fail). The atom
allrefers to all ports. If the port is preceded by a
sign the trace-point is cleared for the port. If it is preceded by a
the trace-point is set.
The predicate trace/2 activates debug mode (see debug/0). Each time a port (of the 4-port model) is passed that has a trace-point set the goal is printed as with trace/0. Unlike trace/0 however, the execution is continued without asking for further information. Examples:
|Trace all ports of hello with any arity in any module.|
|Trace failures of foo/2 in any module.|
|Stop tracing bar/1.|
The predicate debugging/0 shows all currently defined trace-points.
unify. The special shorthand
allrefers to all ports,
fullrefers to all ports except for the unify port (default).
halfrefers to the
fail. If the unknown flag is set to
warning, unknown/2 reports the value as
' was a prefix operator. Inversions after 5.5.13, explicit brackets are needed. or a list of such options. +<option> sets a style checking option, -<option> clears it and ?(<option>) succeeds or fails according to the current setting. consult/1 and derivatives resets the style checking options to their value before loading the file. If---for example---a file containing long atoms should be loaded the user can start the file with:
Currently available options are:
|on||read_clause/1 (used by consult/1) warns on variables only appearing once in a term (clause) which have a name not starting with an underscore. See section 188.8.131.52 for details on variable handling and warnings.|
|on||read/1 and derivatives will produce an error message on quoted atoms or strings longer than 5 lines.|
|off||Accept dollar as a lower case character, thus avoiding the need for quoting atoms with dollar signs. System maintenance use only.|
|on||Warn if the clauses for a predicate are not together in the same source file.|
|off||Backward compatibility. See the Prolog flag double_quotes (current_prolog_flag/2).|
|off||Warn on atoms and variables holding non-ASCII characters that are not quoted. See also section 184.108.40.206.|