Handle generator exceptions in its consumer

Question

This is a follow-up to Handle an exception thrown in a generator and discusses a more general problem.

I have a function that reads data in different formats. All fo

Answer 1

(I answered the other question linked in the OP but my answer applies to this situation as well)

I have needed to solve this problem a couple of times and came upon this question after a search for what other people have done.

One option- which will probably require refactoring things a little bit- would be to simply create an error handling generator, and throw the exception in the generator (to another error handling generator) rather than raise it.

Here is what the error handling generator function might look like:

def err_handler():
    # a generator for processing errors
    while True:
        try:
            # errors are thrown to this point in function
            yield
        except Exception1:
            handle_exc1()
        except Exception2:
            handle_exc2()
        except Exception3:
            handle_exc3()
        except Exception:
            raise

An additional handler argument is provided to the parsefunc function so it has a place to put the errors:

def parsefunc(stream, handler):
    # the handler argument fixes errors/problems separately
    while not eof(stream):
        try:
            rec = read_record(stream)
            do some stuff
            yield rec
        except Exception as e:
            handler.throw(e)
    handler.close()

Now just use almost the original read function, but now with an error handler:

def read(stream, parsefunc):
    handler = err_handler()
    for record in parsefunc(stream, handler):
        do_stuff(record)

This isn't always going to be the best solution, but it's certainly an option, and relatively easy to understand.