Python, import string of Python code as module

Question

In python you can do something like this to import a module using a string filename, and assign its namespace a variable on the local namespace.

x = __import__(str)

I'm wondering if there is a related function that will take take a string of Python code, instead of a path to a file with Python code, and return its namespace as a variable.

For example,

str = "a = 5";
x = importstr(str)
print x.a
#output is 5

I realize that I could write the string to a file, then use __import__ on it, but I'd like to skip the intermediate file if possible.

The reason for this is that I'm experimenting with metaprogramming in python, and it seems like a good solution to what I'm doing.

score 15 · Accepted Answer · answered Sep 01 '10 at 02:02

15

Here's an example of dynamically creating module objects using the imp module

answered Sep 01 '10 at 02:02

Jeremy Brown

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hrm... got my first ever downvote with this answer and I'm not sure why?? – Jeremy Brown Sep 01 '10 at 14:07
@JeremyBrown just the thing I was hunting for. As I up voted it, consider the down vote undone ;) – Anuvrat Parashar Dec 05 '12 at 12:36
9

Please copy the essential answer information from your external links into the answer body. So if and when the remote site ever moves the content or goes down, the solution is not lost. – ThorSummoner Apr 26 '14 at 07:20

score 7 · Answer 2 · answered Feb 11 '15 at 18:31

Unfortunately, the imp module was recently deprecated (I have NO idea why).

Instead, you should do this:

from types import ModuleType
import sys

mod = ModuleType('my_module', 'doc string here')
exec('a = 1', mod.__dict__)
print(mod.a) # prints 1
# add to sys.modules
sys.modules['my_module'] = mod

Or you can use PyExt's RuntimeModule.from_string:

from pyext import RuntimeModule

mod = RuntimeModule.from_string('a = 1')
print(mod.a) # 1

Remi · Answer 3 · 2011-09-25T23:44:46.613

6

Here is how to import a string as a module:

import sys,imp

my_code = 'a = 5'
mymodule = imp.new_module('mymodule')
exec my_code in mymodule.__dict__

so you can now access the module attributes (and functions, classes etc) as:

mymodule.a
>>> 5

To ignore any next attempt to import, add the module to sys:

sys.modules['mymodule'] = mymodule

edited Sep 25 '11 at 23:44

answered Sep 15 '11 at 20:07

Remi

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score 5 · Answer 4 · edited Jun 20 '20 at 09:12

types.ModuleType is not recommended according to Python documentation on module_from_spec():

importlib.util.module_from_spec(spec)

...

This function is preferred over using types.ModuleType to create a new module as spec is used to set as many import-controlled attributes on the module as possible.

Here is what I came up with to load the module from source code.

import importlib.util
spec = importlib.util.spec_from_loader('helper', loader=None)
helper = importlib.util.module_from_spec(spec)
exec('a = 5', helper.__dict__)

print(type(helper)) # prints "<class 'module'>"
helper.a # prints "5"

score 2 · Answer 5 · answered Sep 01 '10 at 02:00

2

Is this something what you're looking for ?

my_namespace = {}
exec "a = 5" in my_namespace
print my_namespace["a"]

answered Sep 01 '10 at 02:00

Tarantula

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i'd prefer not to need to refer to the namespace items using a string – Mike Sep 01 '10 at 02:07

Python, import string of Python code as module

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