Recursive version of 'reload'

Question

When I'm developing Python code, I usually test it in an ad-hoc way in the interpreter. I'll import some_module, test it, find a bug, fix the bug and save, and then use the built-in reload function to reload(some_module) and test again.

However, suppose that in some_module I have import some_other_module, and while testing some_module I discover a bug in some_other_module and fix it. Now calling reload(some_module) won't recursively re-import some_other_module. I have to either manually reimport the dependency (by doing something like reload(some_module.some_other_module), or import some_other_module; reload(some_other_module), or, if I've changed a whole bunch of dependencies and lost track of what I need to reload, I need to restart the entire interpreter.

What'd be more convenient is if there were some recursive_reload function, and I could just do recursive_reload(some_module) and have Python not only reload some_module, but also recursively reload every module that some_module imports (and every module that each of those modules imports, and so on) so that I could be sure that I wasn't using an old version of any of the other modules upon which some_module depends.

I don't think there's anything built in to Python that behaves like the recursive_reload function I describe here, but is there an easy way to hack such a thing together?

Answer 1

I've run up against the same issue, and you inspired me to actually solve the problem.

from types import ModuleType

try:
    from importlib import reload  # Python 3.4+
except ImportError:
    # Needed for Python 3.0-3.3; harmless in Python 2.7 where imp.reload is just an
    # alias for the builtin reload.
    from imp import reload

def rreload(module):
    """Recursively reload modules."""
    reload(module)
    for attribute_name in dir(module):
        attribute = getattr(module, attribute_name)
        if type(attribute) is ModuleType:
            rreload(attribute)

Or, if you are using IPython, just use dreload or pass --deep-reload on startup.

Answer 2

Wouldn't it be simpler to actually write some test cases and run them every time you are done with modifying your module?

What you are doing is cool (you are in essence using TDD (test driven development) but you are doing it wrong.

Consider that with written unit tests(using the default python unittest module, or better yet nose) you get to have tests that are reusable, stable and help you detect inconsitencies in your code much much faster and better than with testing your module in the interactive environment.

Answer 3

I've run against the same issue and I've built up on @Mattew and @osa answer.

from types import ModuleType
import os, sys
def rreload(module, paths=None, mdict=None):
    """Recursively reload modules."""
    if paths is None:
        paths = ['']
    if mdict is None:
        mdict = {}
    if module not in mdict:
        # modules reloaded from this module
        mdict[module] = [] 
    reload(module)
    for attribute_name in dir(module):
        attribute = getattr(module, attribute_name)
        if type(attribute) is ModuleType:
            if attribute not in mdict[module]:
                if attribute.__name__ not in sys.builtin_module_names:
                    if os.path.dirname(attribute.__file__) in paths:
                        mdict[module].append(attribute)
                        rreload(attribute, paths, mdict)
    reload(module)
    #return mdict

There are three differences:

1. In the general case, reload(module) has to be called at the end of the function as well, as @osa pointed out.
2. With circular import dependencies the code posted earlier would loop forever so I've added a dictionary of lists to keep track of the set of modules loaded by other modules. While circular dependencies are not cool, Python allows them, so this reload function deals with them as well.
3. I've added a list of paths (default is ['']) from which the reloading is allowed. Some modules don't like been reloaded the normal way, (as shown here).

Answer 4

Technically, in each file you could put a reload command, to ensure that it reloads each time it imports

a.py:

def testa():
    print 'hi!'

b.py:

import a
reload(a)
def testb():
    a.testa()

Now, interactively:

import b
b.testb()
#hi!

#<modify a.py>

reload(b)
b.testb()
#hello again!

Answer 5

I found the answer of redsk very useful. I propose a simplified (for the user, not as code) version where the path to the module is automatically gathered and recursion works for an arbitrary number of levels. Everything is self-contained in a single function. Tested on Python 3.4. I guess for python 3.3 one must import reload from imp instead of ... from importlib. It also checks if the __file__ file is present, which might be false if the coder forgets to define an __init__.py file in a submodule. In such case, an exception is raised.

def rreload(module):
    """
    Recursive reload of the specified module and (recursively) the used ones.
    Mandatory! Every submodule must have an __init__.py file
    Usage:
        import mymodule
        rreload(mymodule)

    :param module: the module to load (the module itself, not a string)
    :return: nothing
    """

    import os.path
    import sys

    def rreload_deep_scan(module, rootpath, mdict=None):
        from types import ModuleType
        from importlib import reload

        if mdict is None:
            mdict = {}

        if module not in mdict:
            # modules reloaded from this module
            mdict[module] = []
        # print("RReloading " + str(module))
        reload(module)
        for attribute_name in dir(module):
            attribute = getattr(module, attribute_name)
            # print ("for attr "+attribute_name)
            if type(attribute) is ModuleType:
                # print ("typeok")
                if attribute not in mdict[module]:
                    # print ("not int mdict")
                    if attribute.__name__ not in sys.builtin_module_names:
                        # print ("not a builtin")
                        # If the submodule is a python file, it will have a __file__ attribute
                        if not hasattr(attribute, '__file__'):
                            raise BaseException("Could not find attribute __file__ for module '"+str(attribute)+"'. Maybe a missing __init__.py file?")

                        attribute_path = os.path.dirname(attribute.__file__)

                        if attribute_path.startswith(rootpath):
                            # print ("in path")
                            mdict[module].append(attribute)
                            rreload_deep_scan(attribute, rootpath, mdict)

    rreload_deep_scan(module, rootpath=os.path.dirname(module.__file__))

Answer 6

For Python 3.6+ you can use:

from types import ModuleType
import sys
import importlib

def deep_reload(m: ModuleType):
    name = m.__name__  # get the name that is used in sys.modules
    name_ext = name + '.'  # support finding sub modules or packages

    def compare(loaded: str):
        return (loaded == name) or loaded.startswith(name_ext)

    all_mods = tuple(sys.modules)  # prevent changing iterable while iterating over it
    sub_mods = filter(compare, all_mods)
    for pkg in sorted(sub_mods, key=lambda item: item.count('.'), reverse=True):
        importlib.reload(sys.modules[pkg])  # reload packages, beginning with the most deeply nested

Answer 7

It is a tricky thing to do - I have an working example in this answer: how to find list of modules which depend upon a specific module in python