To start up the debugger, either press the 'Watcher' button, or select the 'Watcher' item from the 'Watcher' menu.

or

You should now see the window below:

In order to run the debugger, all you need is to run some code as you normally would, once the debugger is open. But the debugger will only step through code that has been loaded into your editor window, so in order to see the debugger at work, you need to run a function that is defined and loaded in your editor. For example, in your editor, type:

You would then invoke the function by typing 'hello()' in the command window, press enter, and viola! You should see this in the debugger window:

Congratulations, you have used the debugger for the first time!

Okay, that was nice, but a debugger is not really useful until you can see the values of some variables, so lets add some variables to the program. We are going to use the sumlist program, the code looks like:

    def sumlist(list):
        sum = 0
        for item in list:
            sum = sum + item
        return sum


This program has three variables: sum, item, and list. We will watch item and sum. To do this, either press the 'add var' button on the debugger or 'add variable...' from the debugger menu.

When the dialog appear asking for a variable name, type in the name of the variable to watch. So in this case, type 'item', and click OK. You should now see a new column 'var:item' in the table:

Next, do the same for the variable 'sum'. If you want to take a variable off of the table later, just click 'remove var' or 'remove variable...' from the debugger menu. A dialog will appear that lets you choose the variable to remove and then click OK.

Now, that you have added two variables for the debugger to watch, let's run it! Type this in the command window (remember to load your program first):

    sumlist([4,5,2,1])


Rows should be added to the execution table one by one. Wait for execution to stop. (You can also change the speed it's going by moving the slider) When it's finished, you should see this:

As an exercise, please follow each line through the code and understand how each result was gotten.