Debugging a py file

Debugging a py file#

Task 2.1 Set breakpoints and start debugging#

  1. Open debug_example.py and click left of a line number to add a red breakpoint (e.g., on total = 0).

  2. Start debugging: press F5 or click the green ‘Run and Debug’ button while debug_example.py is active.

  3. When execution pauses:

    • Inspect variables in the ‘Variables’ view.

    • Use the ‘Debug Console’ to evaluate expressions (e.g., v).

    • Use the ‘Call Stack’ to see how you got here.

Task 2.2 Step through code#

  1. Click ‘Step Over’ (F10) multiple times: This runs the current line; if it calls a function, executes it without entering and stops at the next line in the same function. Observe how v changes and where the exception occurs.

  2. Test the other stepping commands:

  • ‘Continue’ (F5), runs until the next breakpoint, exception or program end.

  • ‘Step Into’ (F11): Enters the called function and pauses at its first line so you can debug inside it.

  • ‘Step Out’ (Shift+F11)

Task 2.3 Break on exceptions and conditional breakpoints#

  1. In the ‘Breakpoints’ view on the bottom left corner, enable breaking on exceptions (‘Raised Exceptions’ / ‘Uncaught Exceptions’).

  2. Right-click the breakpoint (in the gutter or in the Breakpoints view) → ‘Add conditional breakpoint’ and enter a condition to check the division by zero:

    • If the breakpoint is inside compute_ratio(), use b == 0 (local parameter in that function).

    • If you prefer to stop at the call site, place a breakpoint on total += compute_ratio(10, v) and set condition v == 0, then use F11 (Step Into). Note: If there is already a breakpoint, right-click and use ‘Edit Breakpoint…’.

  3. Press F5. Execution pauses when b is 0. With exception breakpoints enabled, it also pauses on ZeroDivisionError even without a conditional.

Task 2.4 Adapt#

  1. Adapt the code to handle division by zero gracefully, e.g., return 0 instead of raising an exception. While debugging, you can inspect the Variables, which allows you to confirm confirm a == 10, b == 0 at some point. In the Debug Console (in the bottom toolbar) you can debug expressions safely: try a / (b or 1) to probe safely.

  2. Whenever you’re happy with the code, stop debugging (Shift+F5), implement your changes and run the script normally (F5 or Run → Run Without Debugging) to see the output.

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