Skip to content

Interactive Debugging

As shown in the quickstart section "Error-handling", loman makes it easy to see a traceback for any exceptions that are shown while calculating nodes, and also makes it easy to update calculation functions in-place to fix errors. However, it is often desirable to use Python's interactive debugger at the exact time that an error occurs. To support this, the calculate method takes a parameter raise_exceptions. When it is False (the default), nodes are set to state ERROR when exceptions occur during their calculation. When it is set to True any exceptions are not caught, allowing the user to invoke the interactive debugger

comp = Computation()
comp.add_node('numerator', value=1)
comp.add_node('divisor', value=0)
comp.add_node('result', lambda numerator, divisor: numerator / divisor)
comp.compute('result', raise_exceptions=True)

    ---------------------------------------------------------------------------

    ZeroDivisionError                         Traceback (most recent call last)

    <ipython-input-38-4243c7243fc5> in <module>()
    ----> 1 comp.compute('result', raise_exceptions=True)


    [... skipped ...]


    <ipython-input-36-c0efbf5b74f7> in <lambda>(numerator, divisor)
          3 comp.add_node('numerator', value=1)
          4 comp.add_node('divisor', value=0)
    ----> 5 comp.add_node('result', lambda numerator, divisor: numerator / divisor)


    ZeroDivisionError: division by zero

    %debug

    > <ipython-input-36-c0efbf5b74f7>(5)<lambda>()
          1 from loman import *
          2 comp = Computation()
          3 comp.add_node('numerator', value=1)
          4 comp.add_node('divisor', value=0)
    ----> 5 comp.add_node('result', lambda numerator, divisor: numerator / divisor)

    ipdb> p numerator
    1
    ipdb> p divisor
    0