Is Python a

5. Package imports. Import your file from a package. Create a subdirectory calledmypkg nested in a directory on your module import search path, move themymod.py module file you created in exercise 1 or 3 into the new directory, andtry to import it with a package import of the form import mypkg.mymod.You’ll need to add an _ _init_ _.py file in the directory your module was movedto make this go, but it should work on all major Python platforms (that’s part ofthe reason Python uses “.” as a path separator). The package directory you createcan be simply a subdirectory of the one you’re working in; if it is, it will befound via the home directory component of the search path, and you won’t haveto configure your path. Add some code to your _ _init_ _.py, and see if it runs oneach import.6. Reloads. Experiment with module reloads: perform the tests in Chapter 19’schanger.py example, changing the called function’s message, and/or behaviorrepeatedly, without stopping the Python interpreter. Depending on your system,you might be able to edit changer in another window, or suspend the Pythoninterpreter, and edit in the same window (on Unix, a Ctrl-Z key combinationusually suspends the current process, and an fg command later resumes it).7. Circular imports. * In the section on recursive import gotchas, importing recur1raised an error. But, if you restart Python, and import recur2 interactively, theerror doesn’t occur—test and see this for yourself. Why do you think it works toimport recur2, but not recur1? (Hint: Python stores new modules in the built-insys.modules table (a dictionary) before running their code; later imports fetch themodule from this table first, whether the module is “complete” yet or not.) Now,try running recur1 as a top-level script file: python recur1.py. Do you get thesame error that occurs when recur1 is imported interactively? Why? (Hint: whenmodules are run as programs, they aren’t imported, so this case has the sameeffect as importing recur2 interactively; recur2 is the first module imported.)What happens when you run recur2 as a script?* Note that circular imports are extremely rare in practice. In fact, this author has never coded or come acrossa circular import in a decade of Python coding. On the other hand, if you can understand why they are apotential problem, you know a lot about Python’s import semantics.Part V Exercises | 447