Import Local module over global python

Question

I have a 2 python files. One is trying to import the second. My problem is that the second is named math.py. I can not rename it. When I attempt to call a function that is located inside math.py, I can not because I end up with the global math module. How would I import my local file instead of the global. I am using Python 2.7, and this is(roughly) my import statment:

cstr = "math"
command = __import__(cstr)

Later I try:

command.in_math_py_not_global()

Edit: a more complete example:

def parse(self,string):
    clist = string.split(" ")
    cstr= clist[0]
    args = clist[1:len(clist)]
    rvals = []
    try:
        command = __import__(cstr)
        try:
            rvals.extend(command.main(args))
        except:
            print sys.exc_info()
    except ImportError:
        print "Command not valid"

I just tried creating a test.py with import math, and a math.py in the same directory, and it worked fine. I could call math.foo() in my own math.py with no problem. — Greg Hewgill
– Greg Hewgill, Commented Jul 15, 2012 at 4:10
I get AttributeError("'module' object has no attribute 'main'",) — jbills
– jbills, Commented Jul 15, 2012 at 4:22
Can you provide a small, complete example that shows exactly what you are doing to cause that error? — Greg Hewgill
– Greg Hewgill, Commented Jul 15, 2012 at 4:24
There, I am basicly letting the user input a string, with the first word of that string used as a command. The command is passed on to a module named after the command. In this case I have math with a file called math.py. — jbills
– jbills, Commented Jul 15, 2012 at 4:28

Greg Hewgill · Accepted Answer · 2012-07-15 04:37:02Z

Python processes have a single namespace of loaded modules. If you (or any other module) has already loaded the standard math module for any reason, then trying to load it again with import or __import__() will simply return a reference to the already-loaded module. You should be able to verify this using print id(math) and comparing with print id(command).

Although you've stated that you are unable to change the name of math.py, I suggest you can. You are getting the name of the module to load from the user. You can modify this before actually using the __import__() function to add a prefix. For example:

command = __import__("cmd_" + cstr)

Then, rename math.py to cmd_math.py and you will avoid this conflict.

Thanks, I'll try your second suggestion. The first did not work, I got a name error saying math is not defined.

Acorn · Accepted Answer · 2012-07-15 08:24:09Z

3

You could use relative imports:

from . import math

http://docs.python.org/tutorial/modules.html#intra-package-references

answered Jul 15, 2012 at 8:24

Acorn

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1 Comment

jbills Over a year ago

Thats not good enough for what I need. In any case I have tried that and only gotten package errors.

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