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Move the mouse cursor into the break window. Hold the middle button down, and a new menu will pop up, like the one in Figure 10-3.
Figure 10-3. Middle Button Menu in Break window
Five of the selections are particularly important when just starting to use Medley:
BT Back Trace displays the stack in a menu beside the break window. Back
Trace is a very powerful debugging tool. Each function call is placed on the
stack and removed when the execution of that function is complete. Choosing an item on the stack will open another window displaying that item’s local
variables and their bindings. This is an inspector window that offers all the power of the inspector. (For details, see the section on the Inspector, Chapter 17.)
? = Before you use this menu option, display the stack by choosing BT from this menu, and choose a function from it. Now, choose ?=. It will display the
current values of the arguments to the function that has been chosen from the stack.
Move back to the previous break window, or if there is no other break window, back to the top level, the Executive Window.
REVERT Move the point of execution back to a specified function call before the error. The function to revert back to is, by default, the last function call before the break. If, however, a different function call is chosen on the BT menu, revert will go back to the start of this function and open a new break window. The
items on the stack above the new starting place will no longer exist. This is used in the tutorial example (see the Break Package Example section above).
OK Continue execution from the point of the break. This is useful if you have a simple error, i.e., an unbound variable or a nonnumeric argument to an
arithmetic function. Reset the variable in the break window, then select OK. (see the Break Package Example section above).
In addition to being available on the middle button menu of the break window, all of these functions can be typed directly into the window. Only BT behaves differently
when typed. It types the stack into the trace window instead of opening a new window.)