The current implementation provides no support for an interactive debugger, although a future version will. Nevertheless, S-Lang has several features that aid the programmer in tracking down problems, including function call tracebacks and the tracing of function calls. However, the biggest debugging aid stems from the fact that the language is interpreted permitting one to easily add debugging statements to the code.
To enable debugging information, add the lines
_debug_info = 1;
_traceback = 1;
_debug_info variable to
1 causes line number information to be compiled into the
functions when the file is loaded. The _traceback variable
controls whether or not traceback information should be generated.
If it is set to 1, the values of local variables will be
dumped when the traceback is generated. Setting this variable
to -1 will cause only function names to be reported in the
traceback.
Here is an example of a traceback report:
S-Lang Traceback: error
S-Lang Traceback: verror
S-Lang Traceback: (Error occurred on line 65)
S-Lang Traceback: search_generic_search
Local Variables:
$0: Type: String_Type, Value: "Search forward:"
$1: Type: Integer_Type, Value: 1
$2: Type: Ref_Type, Value: _function_return_1
$3: Type: String_Type, Value: "abcdefg"
$4: Type: Integer_Type, Value: 1
S-Lang Traceback: (Error occurred on line 72)
S-Lang Traceback: search_forward
72,
the search_forward function called the
search_generic_search function. On line 65 it called the
verror function, which called error. The
search_generic_search function contains 5 local variables
and are represented symbolically as $0 through $4.