Dynamic loading of python modules

Question

In python how do you dynamically add modules to a package while your program is running.

I want to be able to add modules to the package directory from an outside pr

Answer 1

Bastien already answered the question, anyway you may find useful this function I use to load all the modules from a subfolder in a dictionary:

def loadModules():
    res = {}
    import os
    # check subfolders
    lst = os.listdir("services")
    dir = []
    for d in lst:
        s = os.path.abspath("services") + os.sep + d
        if os.path.isdir(s) and os.path.exists(s + os.sep + "__init__.py"):
            dir.append(d)
    # load the modules
    for d in dir:
        res[d] = __import__("services." + d, fromlist = ["*"])
    return res

This other one is to instantiate an object by a class defined in one of the modules loaded by the first function:

def getClassByName(module, className):
    if not module:
        if className.startswith("services."):
            className = className.split("services.")[1]
        l = className.split(".")
        m = __services__[l[0]]
        return getClassByName(m, ".".join(l[1:]))
    elif "." in className:
        l = className.split(".")
        m = getattr(module, l[0])
        return getClassByName(m, ".".join(l[1:]))
    else:
        return getattr(module, className)

A simple way to use those functions is this:

mods = loadModules()
cls = getClassByName(mods["MyModule"], "submodule.filepy.Class")
obj = cls()

Obviously you can replace all the "services" subfolder references with parameters.