debug_messages

By default, debug and debug(Group) messages are only printed when the debug flag is turned on. These messages are also suppressed when compiling code with the optimize flag turned on. This tool supports selective enabling of debug and debug(Group) messages in normal and debug modes.

API documentation

This tool API documentation is available at:

../../docs/library_index.html#debug-messages

For general information on debugging, open in a web browser the following link and consult the debugging section of the User Manual:

../../manuals/userman/debugging.html

Loading

This tool can be loaded using the query:

| ?- logtalk_load(debug_messages(loader)).

Usage

The tool provides two sets of predicates. The first set allows enabling and disabling of all debug and debug(Group) messages for a given component. The second set allows enabling and disabling of debug(Group) messages for a given group and component for fine-grained control.

Upon loading the tool, all debug messages are skipped. The user is then expected to use the tool API to selectively enable the messages that will be printed. As an example, consider the following object, part of a xyz component:

:- object(foo).

    :- public([bar/0, baz/0]).
    :- uses(logtalk, [print_message/3]).

    bar :-
        print_message(debug(bar), xyz, @'bar/0 called').

    baz :-
        print_message(debug(baz), xyz, @'baz/0 called').

:- end_object.

Assuming the object foo is compiled and loaded in normal or debug mode, after also loading this tool, bar/0 and baz/0 messages will not print any debug messages:

| ?- {debug_messages(loader), foo}.
...
yes

| ?- foo::(bar, baz).
yes

We can then enable all debug messages for the xyz component:

| ?- debug_messages::enable(xyx).
yes

| ?- foo::(bar, baz).
bar/0 called
baz/0 called
yes

Or we can selectively enable only debug messages for a specific group:

| ?- debug_messages::disable(xyx).
yes

| ?- debug_messages::enable(xyx, bar).
yes

| ?- foo::(bar, baz).
bar/0 called
yes

Other notes

All source files are indented using tabs (a common setting is a tab width equivalent to 4 spaces).