Add way to launch debugger once only

[stuaxo]

Often I'm debugging something that may run several times (it may be some code in a unit test), I want a way to trigger ipdb only on the first time.

At the moment I might do something hacky like this:

def test_some_pytest_test():
    if not hasattr(test_some_pytest_test, "has_run"):
        setattr(test_some_pytest_test, "has_run", True)
        ipdb.set_trace()

But more often I put in a single set_trace(), continue everything with "c" then frantically hit Ctrl-C... (usually "q" doesn't actually quit in unit tests).

So it would be nice to have a proper way of just breaking once, this could be a new API call or maybe passing a parameter to launch_ipdb_on_exception.

[alexandrebarbaruiva]

You can use ipdb.set_trace(cond=first_run), it'll only run when first_run is True

[stuaxo]

Is first_run a variable I keep track of ?

[alexandrebarbaruiva]

@stuaxo you create a variable first_run or whatever you want to name it

[alexandrebarbaruiva]

cond checks if a given value is true to stop on breakpoint