Track program execution.
Debugging commands are essential to find programming errors. They help with inspecting programs and data, to pause a program, to find out why a program takes too much time, and much more. Logo can pause because of several reasons:
PAUSEcommand has been executed
The debugging icons in the Toolbar have the following meaning:
|F3|| ||Halts a program and returns to toplevel.|
|F4|| ||Pauses a program and enters Pause mode.|
Prints a backtrace.
Ends a pause.
CONTINUE ends a pause. A Logo program can pause because is it is stepped (see
STEP), because a breakpoint has been hit, or the
PAUSE command has been executed, or if Logo has hit a runtime error.
NOTE: The abbreviation
CO is usually an abbreviation for the
ALL command. Only during a pause,
CO is redefined to CONTINUE.
Outputs the number of microseconds spent inside a procedure.
EXECTIME outputs a timer value in microseconds. This timer is local to a procedure and starts once the procedure is invoked. EXECTIME is handy to measure execution times of a procedure.
Pauses a procedure.
PAUSE temporarily halts the execution of a procedure. PAUSE makes it possible to check
variables or change the environment during the execution of a procedure. Using the PAUSE
command is equivalent to setting a breakpoint in the editor window. When Logo pauses,
the editor windows are set to read-only, because the procedure environment is “frozen”.
DEFINE are also disabled when Logo pauses. To resume
execution of the procedure, press the GO button or type CO or
CONTINUE. To return
to toplevel, press the STOP button or type
TOPLEVEL. PAUSE may only be used within
TO SQUAREDRAW FORWARD 60 RT 90 PAUSE REPEAT 3 [FD 60 RT 90] END SQUAREDRAW