Develop Reference

How to make Python imports dynamic? [duplicate]

How can I import an arbitrary python source file (whose filename could contain any characters, and does not always ends with .py) in Python 3.3+?
I used imp.load_module as follows:
>>> import imp
>>> path = '/tmp/a-b.txt'
>>> with open(path, 'U') as f:
... mod = imp.load_module('a_b', f, path, ('.py', 'U', imp.PY_SOURCE))
...
>>> mod
<module 'a_b' from '/tmp/a-b.txt'>
It still works in Python 3.3, but according to imp.load_module documentation, it is deprecated:
Deprecated since version 3.3: Unneeded as loaders should be used to
load modules and find_module() is deprecated.
and imp module documentation recommends to use importlib:
Note New programs should use importlib rather than this module.
What is the proper way to load an arbitrary python source file in Python 3.3+ without using the deprecated imp.load_module function?

Found a solution from importlib test code.
Using importlib.machinery.SourceFileLoader:
>>> import importlib.machinery
>>> loader = importlib.machinery.SourceFileLoader('a_b', '/tmp/a-b.txt')
>>> mod = loader.load_module()
>>> mod
<module 'a_b' from '/tmp/a-b.txt'>
NOTE: only works in Python 3.3+.
UPDATE Loader.load_module is deprecated since Python 3.4. Use Loader.exec_module instead:
>>> import types
>>> import importlib.machinery
>>> loader = importlib.machinery.SourceFileLoader('a_b', '/tmp/a-b.txt')
>>> mod = types.ModuleType(loader.name)
>>> loader.exec_module(mod)
>>> mod
<module 'a_b'>
>>> import importlib.machinery
>>> import importlib.util
>>> loader = importlib.machinery.SourceFileLoader('a_b', '/tmp/a-b.txt')
>>> spec = importlib.util.spec_from_loader(loader.name, loader)
>>> mod = importlib.util.module_from_spec(spec)
>>> loader.exec_module(mod)
>>> mod
<module 'a_b' from '/tmp/a-b.txt'>

Updated for Python >= 3.8:
Short version:
>>> # https://docs.python.org/3/library/importlib.html#importing-a-source-file-directly
>>> import importlib.util, sys
>>> spec = importlib.util.spec_from_file_location(modname, fname)
>>> module = importlib.util.module_from_spec(spec)
>>> sys.modules[modname] = module
>>> spec.loader.exec_module(module)
Full version:
>>> import importlib.util
>>> import sys
>>> from pathlib import Path
>>> from typing import TYPE_CHECKING
>>>
>>>
>>> if TYPE_CHECKING:
... import types
...
...
>>> def import_source_file(fname: str | Path, modname: str) -> "types.ModuleType":
... """
... Import a Python source file and return the loaded module.
... Args:
... fname: The full path to the source file. It may container characters like `.`
... or `-`.
... modname: The name for the loaded module. It may contain `.` and even characters
... that would normally not be allowed (e.g., `-`).
... Return:
... The imported module
... Raises:
... ImportError: If the file cannot be imported (e.g, if it's not a `.py` file or if
... it does not exist).
... Exception: Any exception that is raised while executing the module (e.g.,
... :exc:`SyntaxError). These are errors made by the author of the module!
... """
... # https://docs.python.org/3/library/importlib.html#importing-a-source-file-directly
... spec = importlib.util.spec_from_file_location(modname, fname)
... if spec is None:
... raise ImportError(f"Could not load spec for module '{modname}' at: {fname}")
... module = importlib.util.module_from_spec(spec)
... sys.modules[modname] = module
... try:
... spec.loader.exec_module(module)
... except FileNotFoundError as e:
... raise ImportError(f"{e.strerror}: {fname}") from e
... return module
...
>>> import_source_file(Path("/tmp/my_mod.py"), "my_mod")
<module 'my_mod' from '/tmp/my_mod.py'>
Original answer for Python 3.5 and 3.6
Shorter version of #falsetru 's solution:
>>> import importlib.util
>>> spec = importlib.util.spec_from_file_location('a_b', '/tmp/a-b.py')
>>> mod = importlib.util.module_from_spec(spec)
>>> spec.loader.exec_module(mod)
>>> mod
<module 'a_b' from '/tmp/a-b.txt'>
I tested it with Python 3.5 and 3.6.
According to the comments, it does not work with arbitrary file extensions.

Similar to #falsetru but for Python 3.5+ and accounting for what the importlib doc states on using importlib.util.module_from_spec over types.ModuleType:
This function [importlib.util.module_from_spec] 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.
We are able to import any file with importlib alone by modifying the importlib.machinery.SOURCE_SUFFIXES list.
import importlib
importlib.machinery.SOURCE_SUFFIXES.append('') # empty string to allow any file
spec = importlib.util.spec_from_file_location(module_name, file_path)
module = importlib.util.module_from_spec(spec)
spec.loader.exec_module(module)
# if desired: importlib.machinery.SOURCE_SUFFIXES.pop()

importlib helper function
Here is a convenient, ready-to-use helper to replace imp, with an example. The technique is the same as that of https://stackoverflow.com/a/19011259/895245 , this is just providing a more convenient function.
main.py
#!/usr/bin/env python3
import os
import importlib
def import_path(path):
module_name = os.path.basename(path).replace('-', '_')
spec = importlib.util.spec_from_loader(
module_name,
importlib.machinery.SourceFileLoader(module_name, path)
)
module = importlib.util.module_from_spec(spec)
spec.loader.exec_module(module)
sys.modules[module_name] = module
return module
notmain = import_path('not-main')
print(notmain)
print(notmain.x)
not-main
x = 1
Run:
python3 main.py
Output:
<module 'not_main' from 'not-main'>
1
I replace - with _ because my importable Python executables without extension have hyphens as in my-cmd. This is not mandatory, but produces better module names like my_cmd.
This pattern is also mentioned in the docs at: https://docs.python.org/3.7/library/importlib.html#importing-a-source-file-directly
I ended up moving to it because after updating to Python 3.7, import imp prints:
DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses
and I don't know how to turn that off, this was asked at:
The imp module is deprecated
How to ignore deprecation warnings in Python
Tested in Python 3.7.3.

after many failure solutions this one works for me
def _import(func,*args):
import os
from importlib import util
module_name = "my_module"
BASE_DIR = "wanted module directory path"
path = os.path.join(BASE_DIR,module_name)
spec = util.spec_from_file_location(func, path)
mod = util.module_from_spec(spec)
spec.loader.exec_module(mod)
return getattr(mod,func)(*args)
and to call it just write the function name and it's parameters _import("function",*args)

Dynamically import two files into another file in python which those two files are in the dufferent directories [duplicate]

How can I import an arbitrary python source file (whose filename could contain any characters, and does not always ends with .py) in Python 3.3+?
I used imp.load_module as follows:
>>> import imp
>>> path = '/tmp/a-b.txt'
>>> with open(path, 'U') as f:
... mod = imp.load_module('a_b', f, path, ('.py', 'U', imp.PY_SOURCE))
...
>>> mod
<module 'a_b' from '/tmp/a-b.txt'>
It still works in Python 3.3, but according to imp.load_module documentation, it is deprecated:
Deprecated since version 3.3: Unneeded as loaders should be used to
load modules and find_module() is deprecated.
and imp module documentation recommends to use importlib:
Note New programs should use importlib rather than this module.
What is the proper way to load an arbitrary python source file in Python 3.3+ without using the deprecated imp.load_module function?

Found a solution from importlib test code.
Using importlib.machinery.SourceFileLoader:
>>> import importlib.machinery
>>> loader = importlib.machinery.SourceFileLoader('a_b', '/tmp/a-b.txt')
>>> mod = loader.load_module()
>>> mod
<module 'a_b' from '/tmp/a-b.txt'>
NOTE: only works in Python 3.3+.
UPDATE Loader.load_module is deprecated since Python 3.4. Use Loader.exec_module instead:
>>> import types
>>> import importlib.machinery
>>> loader = importlib.machinery.SourceFileLoader('a_b', '/tmp/a-b.txt')
>>> mod = types.ModuleType(loader.name)
>>> loader.exec_module(mod)
>>> mod
<module 'a_b'>
>>> import importlib.machinery
>>> import importlib.util
>>> loader = importlib.machinery.SourceFileLoader('a_b', '/tmp/a-b.txt')
>>> spec = importlib.util.spec_from_loader(loader.name, loader)
>>> mod = importlib.util.module_from_spec(spec)
>>> loader.exec_module(mod)
>>> mod
<module 'a_b' from '/tmp/a-b.txt'>

Updated for Python >= 3.8:
Short version:
>>> # https://docs.python.org/3/library/importlib.html#importing-a-source-file-directly
>>> import importlib.util, sys
>>> spec = importlib.util.spec_from_file_location(modname, fname)
>>> module = importlib.util.module_from_spec(spec)
>>> sys.modules[modname] = module
>>> spec.loader.exec_module(module)
Full version:
>>> import importlib.util
>>> import sys
>>> from pathlib import Path
>>> from typing import TYPE_CHECKING
>>>
>>>
>>> if TYPE_CHECKING:
... import types
...
...
>>> def import_source_file(fname: str | Path, modname: str) -> "types.ModuleType":
... """
... Import a Python source file and return the loaded module.
... Args:
... fname: The full path to the source file. It may container characters like `.`
... or `-`.
... modname: The name for the loaded module. It may contain `.` and even characters
... that would normally not be allowed (e.g., `-`).
... Return:
... The imported module
... Raises:
... ImportError: If the file cannot be imported (e.g, if it's not a `.py` file or if
... it does not exist).
... Exception: Any exception that is raised while executing the module (e.g.,
... :exc:`SyntaxError). These are errors made by the author of the module!
... """
... # https://docs.python.org/3/library/importlib.html#importing-a-source-file-directly
... spec = importlib.util.spec_from_file_location(modname, fname)
... if spec is None:
... raise ImportError(f"Could not load spec for module '{modname}' at: {fname}")
... module = importlib.util.module_from_spec(spec)
... sys.modules[modname] = module
... try:
... spec.loader.exec_module(module)
... except FileNotFoundError as e:
... raise ImportError(f"{e.strerror}: {fname}") from e
... return module
...
>>> import_source_file(Path("/tmp/my_mod.py"), "my_mod")
<module 'my_mod' from '/tmp/my_mod.py'>
Original answer for Python 3.5 and 3.6
Shorter version of #falsetru 's solution:
>>> import importlib.util
>>> spec = importlib.util.spec_from_file_location('a_b', '/tmp/a-b.py')
>>> mod = importlib.util.module_from_spec(spec)
>>> spec.loader.exec_module(mod)
>>> mod
<module 'a_b' from '/tmp/a-b.txt'>
I tested it with Python 3.5 and 3.6.
According to the comments, it does not work with arbitrary file extensions.

Similar to #falsetru but for Python 3.5+ and accounting for what the importlib doc states on using importlib.util.module_from_spec over types.ModuleType:
This function [importlib.util.module_from_spec] 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.
We are able to import any file with importlib alone by modifying the importlib.machinery.SOURCE_SUFFIXES list.
import importlib
importlib.machinery.SOURCE_SUFFIXES.append('') # empty string to allow any file
spec = importlib.util.spec_from_file_location(module_name, file_path)
module = importlib.util.module_from_spec(spec)
spec.loader.exec_module(module)
# if desired: importlib.machinery.SOURCE_SUFFIXES.pop()

importlib helper function
Here is a convenient, ready-to-use helper to replace imp, with an example. The technique is the same as that of https://stackoverflow.com/a/19011259/895245 , this is just providing a more convenient function.
main.py
#!/usr/bin/env python3
import os
import importlib
def import_path(path):
module_name = os.path.basename(path).replace('-', '_')
spec = importlib.util.spec_from_loader(
module_name,
importlib.machinery.SourceFileLoader(module_name, path)
)
module = importlib.util.module_from_spec(spec)
spec.loader.exec_module(module)
sys.modules[module_name] = module
return module
notmain = import_path('not-main')
print(notmain)
print(notmain.x)
not-main
x = 1
Run:
python3 main.py
Output:
<module 'not_main' from 'not-main'>
1
I replace - with _ because my importable Python executables without extension have hyphens as in my-cmd. This is not mandatory, but produces better module names like my_cmd.
This pattern is also mentioned in the docs at: https://docs.python.org/3.7/library/importlib.html#importing-a-source-file-directly
I ended up moving to it because after updating to Python 3.7, import imp prints:
DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses
and I don't know how to turn that off, this was asked at:
The imp module is deprecated
How to ignore deprecation warnings in Python
Tested in Python 3.7.3.

after many failure solutions this one works for me
def _import(func,*args):
import os
from importlib import util
module_name = "my_module"
BASE_DIR = "wanted module directory path"
path = os.path.join(BASE_DIR,module_name)
spec = util.spec_from_file_location(func, path)
mod = util.module_from_spec(spec)
spec.loader.exec_module(mod)
return getattr(mod,func)(*args)
and to call it just write the function name and it's parameters _import("function",*args)

How can you import packages in a python for loop? [duplicate]

I'm writing a Python application that takes a command as an argument, for example:
$ python myapp.py command1
I want the application to be extensible, that is, to be able to add new modules that implement new commands without having to change the main application source. The tree looks something like:
myapp/
__init__.py
commands/
__init__.py
command1.py
command2.py
foo.py
bar.py
So I want the application to find the available command modules at runtime and execute the appropriate one.
Python defines an __import__() function, which takes a string for a module name:
__import__(name, globals=None, locals=None, fromlist=(), level=0)
The function imports the module name, potentially using the given globals and locals to determine how to interpret the name in a package context. The fromlist gives the names of objects or submodules that should be imported from the module given by name.
Source: https://docs.python.org/3/library/functions.html#__import__
So currently I have something like:
command = sys.argv[1]
try:
command_module = __import__("myapp.commands.%s" % command, fromlist=["myapp.commands"])
except ImportError:
# Display error message
command_module.run()
This works just fine, I'm just wondering if there is possibly a more idiomatic way to accomplish what we are doing with this code.
Note that I specifically don't want to get in to using eggs or extension points. This is not an open-source project and I don't expect there to be "plugins". The point is to simplify the main application code and remove the need to modify it each time a new command module is added.
See also: How do I import a module given the full path?

With Python older than 2.7/3.1, that's pretty much how you do it.
For newer versions, see importlib.import_module for Python 2 and Python 3.
Or using __import__ you can import a list of modules by doing this:
>>> moduleNames = ['sys', 'os', 're', 'unittest']
>>> moduleNames
['sys', 'os', 're', 'unittest']
>>> modules = map(__import__, moduleNames)
Ripped straight from Dive Into Python.

The recommended way for Python 2.7 and 3.1 and later is to use importlib module:
importlib.import_module(name, package=None)
Import a module. The name argument specifies what module to import in absolute or relative terms (e.g. either pkg.mod or ..mod). If the name is specified in relative terms, then the package argument must be set to the name of the package which is to act as the anchor for resolving the package name (e.g. import_module('..mod', 'pkg.subpkg') will import pkg.mod).
e.g.
my_module = importlib.import_module('os.path')

Note: imp is deprecated since Python 3.4 in favor of importlib
As mentioned the imp module provides you loading functions:
imp.load_source(name, path)
imp.load_compiled(name, path)
I've used these before to perform something similar.
In my case I defined a specific class with defined methods that were required.
Once I loaded the module I would check if the class was in the module, and then create an instance of that class, something like this:
import imp
import os
def load_from_file(filepath):
class_inst = None
expected_class = 'MyClass'
mod_name,file_ext = os.path.splitext(os.path.split(filepath)[-1])
if file_ext.lower() == '.py':
py_mod = imp.load_source(mod_name, filepath)
elif file_ext.lower() == '.pyc':
py_mod = imp.load_compiled(mod_name, filepath)
if hasattr(py_mod, expected_class):
class_inst = getattr(py_mod, expected_class)()
return class_inst

Using importlib
Importing a source file
Here is a slightly adapted example from the documentation:
import sys
import importlib.util
file_path = 'pluginX.py'
module_name = 'pluginX'
spec = importlib.util.spec_from_file_location(module_name, file_path)
module = importlib.util.module_from_spec(spec)
spec.loader.exec_module(module)
# Verify contents of the module:
print(dir(module))
From here, module will be a module object representing the pluginX module (the same thing that would be assigned to pluginX by doing import pluginX). Thus, to call e.g. a hello function (with no parameters) defined in pluginX, use module.hello().
To get the effect "importing" functionality from the module instead, store it in the in-memory cache of loaded modules, and then do the corresponding from import:
sys.modules[module_name] = module
from pluginX import hello
hello()
Importing a package
To import a package instead, calling import_module is sufficient. Suppose there is a package folder pluginX in the current working directory; then just do
import importlib
pkg = importlib.import_module('pluginX')
# check if it's all there..
print(dir(pkg))

Use the imp module, or the more direct __import__() function.

You can use exec:
exec("import myapp.commands.%s" % command)

If you want it in your locals:
>>> mod = 'sys'
>>> locals()['my_module'] = __import__(mod)
>>> my_module.version
'2.6.6 (r266:84297, Aug 24 2010, 18:46:32) [MSC v.1500 32 bit (Intel)]'
same would work with globals()

Similar as #monkut 's solution but reusable and error tolerant described here http://stamat.wordpress.com/dynamic-module-import-in-python/:
import os
import imp
def importFromURI(uri, absl):
mod = None
if not absl:
uri = os.path.normpath(os.path.join(os.path.dirname(__file__), uri))
path, fname = os.path.split(uri)
mname, ext = os.path.splitext(fname)
if os.path.exists(os.path.join(path,mname)+'.pyc'):
try:
return imp.load_compiled(mname, uri)
except:
pass
if os.path.exists(os.path.join(path,mname)+'.py'):
try:
return imp.load_source(mname, uri)
except:
pass
return mod

The below piece worked for me:
>>>import imp;
>>>fp, pathname, description = imp.find_module("/home/test_module");
>>>test_module = imp.load_module("test_module", fp, pathname, description);
>>>print test_module.print_hello();
if you want to import in shell-script:
python -c '<above entire code in one line>'

The following worked for me:
import sys, glob
sys.path.append('/home/marc/python/importtest/modus')
fl = glob.glob('modus/*.py')
modulist = []
adapters=[]
for i in range(len(fl)):
fl[i] = fl[i].split('/')[1]
fl[i] = fl[i][0:(len(fl[i])-3)]
modulist.append(getattr(__import__(fl[i]),fl[i]))
adapters.append(modulist[i]())
It loads modules from the folder 'modus'. The modules have a single class with the same name as the module name. E.g. the file modus/modu1.py contains:
class modu1():
def __init__(self):
self.x=1
print self.x
The result is a list of dynamically loaded classes "adapters".

python: how to import a generated module [duplicate]

I'm writing a Python application that takes a command as an argument, for example:
$ python myapp.py command1
I want the application to be extensible, that is, to be able to add new modules that implement new commands without having to change the main application source. The tree looks something like:
myapp/
__init__.py
commands/
__init__.py
command1.py
command2.py
foo.py
bar.py
So I want the application to find the available command modules at runtime and execute the appropriate one.
Python defines an __import__() function, which takes a string for a module name:
__import__(name, globals=None, locals=None, fromlist=(), level=0)
The function imports the module name, potentially using the given globals and locals to determine how to interpret the name in a package context. The fromlist gives the names of objects or submodules that should be imported from the module given by name.
Source: https://docs.python.org/3/library/functions.html#__import__
So currently I have something like:
command = sys.argv[1]
try:
command_module = __import__("myapp.commands.%s" % command, fromlist=["myapp.commands"])
except ImportError:
# Display error message
command_module.run()
This works just fine, I'm just wondering if there is possibly a more idiomatic way to accomplish what we are doing with this code.
Note that I specifically don't want to get in to using eggs or extension points. This is not an open-source project and I don't expect there to be "plugins". The point is to simplify the main application code and remove the need to modify it each time a new command module is added.
See also: How do I import a module given the full path?

With Python older than 2.7/3.1, that's pretty much how you do it.
For newer versions, see importlib.import_module for Python 2 and Python 3.
Or using __import__ you can import a list of modules by doing this:
>>> moduleNames = ['sys', 'os', 're', 'unittest']
>>> moduleNames
['sys', 'os', 're', 'unittest']
>>> modules = map(__import__, moduleNames)
Ripped straight from Dive Into Python.

The recommended way for Python 2.7 and 3.1 and later is to use importlib module:
importlib.import_module(name, package=None)
Import a module. The name argument specifies what module to import in absolute or relative terms (e.g. either pkg.mod or ..mod). If the name is specified in relative terms, then the package argument must be set to the name of the package which is to act as the anchor for resolving the package name (e.g. import_module('..mod', 'pkg.subpkg') will import pkg.mod).
e.g.
my_module = importlib.import_module('os.path')

Note: imp is deprecated since Python 3.4 in favor of importlib
As mentioned the imp module provides you loading functions:
imp.load_source(name, path)
imp.load_compiled(name, path)
I've used these before to perform something similar.
In my case I defined a specific class with defined methods that were required.
Once I loaded the module I would check if the class was in the module, and then create an instance of that class, something like this:
import imp
import os
def load_from_file(filepath):
class_inst = None
expected_class = 'MyClass'
mod_name,file_ext = os.path.splitext(os.path.split(filepath)[-1])
if file_ext.lower() == '.py':
py_mod = imp.load_source(mod_name, filepath)
elif file_ext.lower() == '.pyc':
py_mod = imp.load_compiled(mod_name, filepath)
if hasattr(py_mod, expected_class):
class_inst = getattr(py_mod, expected_class)()
return class_inst

Using importlib
Importing a source file
Here is a slightly adapted example from the documentation:
import sys
import importlib.util
file_path = 'pluginX.py'
module_name = 'pluginX'
spec = importlib.util.spec_from_file_location(module_name, file_path)
module = importlib.util.module_from_spec(spec)
spec.loader.exec_module(module)
# Verify contents of the module:
print(dir(module))
From here, module will be a module object representing the pluginX module (the same thing that would be assigned to pluginX by doing import pluginX). Thus, to call e.g. a hello function (with no parameters) defined in pluginX, use module.hello().
To get the effect "importing" functionality from the module instead, store it in the in-memory cache of loaded modules, and then do the corresponding from import:
sys.modules[module_name] = module
from pluginX import hello
hello()
Importing a package
To import a package instead, calling import_module is sufficient. Suppose there is a package folder pluginX in the current working directory; then just do
import importlib
pkg = importlib.import_module('pluginX')
# check if it's all there..
print(dir(pkg))

Use the imp module, or the more direct __import__() function.

You can use exec:
exec("import myapp.commands.%s" % command)

If you want it in your locals:
>>> mod = 'sys'
>>> locals()['my_module'] = __import__(mod)
>>> my_module.version
'2.6.6 (r266:84297, Aug 24 2010, 18:46:32) [MSC v.1500 32 bit (Intel)]'
same would work with globals()

Similar as #monkut 's solution but reusable and error tolerant described here http://stamat.wordpress.com/dynamic-module-import-in-python/:
import os
import imp
def importFromURI(uri, absl):
mod = None
if not absl:
uri = os.path.normpath(os.path.join(os.path.dirname(__file__), uri))
path, fname = os.path.split(uri)
mname, ext = os.path.splitext(fname)
if os.path.exists(os.path.join(path,mname)+'.pyc'):
try:
return imp.load_compiled(mname, uri)
except:
pass
if os.path.exists(os.path.join(path,mname)+'.py'):
try:
return imp.load_source(mname, uri)
except:
pass
return mod

The below piece worked for me:
>>>import imp;
>>>fp, pathname, description = imp.find_module("/home/test_module");
>>>test_module = imp.load_module("test_module", fp, pathname, description);
>>>print test_module.print_hello();
if you want to import in shell-script:
python -c '<above entire code in one line>'

The following worked for me:
import sys, glob
sys.path.append('/home/marc/python/importtest/modus')
fl = glob.glob('modus/*.py')
modulist = []
adapters=[]
for i in range(len(fl)):
fl[i] = fl[i].split('/')[1]
fl[i] = fl[i][0:(len(fl[i])-3)]
modulist.append(getattr(__import__(fl[i]),fl[i]))
adapters.append(modulist[i]())
It loads modules from the folder 'modus'. The modules have a single class with the same name as the module name. E.g. the file modus/modu1.py contains:
class modu1():
def __init__(self):
self.x=1
print self.x
The result is a list of dynamically loaded classes "adapters".

Import arbitrary python source file. (Python 3.3+)

How can I import an arbitrary python source file (whose filename could contain any characters, and does not always ends with .py) in Python 3.3+?
I used imp.load_module as follows:
>>> import imp
>>> path = '/tmp/a-b.txt'
>>> with open(path, 'U') as f:
... mod = imp.load_module('a_b', f, path, ('.py', 'U', imp.PY_SOURCE))
...
>>> mod
<module 'a_b' from '/tmp/a-b.txt'>
It still works in Python 3.3, but according to imp.load_module documentation, it is deprecated:
Deprecated since version 3.3: Unneeded as loaders should be used to
load modules and find_module() is deprecated.
and imp module documentation recommends to use importlib:
Note New programs should use importlib rather than this module.
What is the proper way to load an arbitrary python source file in Python 3.3+ without using the deprecated imp.load_module function?

Found a solution from importlib test code.
Using importlib.machinery.SourceFileLoader:
>>> import importlib.machinery
>>> loader = importlib.machinery.SourceFileLoader('a_b', '/tmp/a-b.txt')
>>> mod = loader.load_module()
>>> mod
<module 'a_b' from '/tmp/a-b.txt'>
NOTE: only works in Python 3.3+.
UPDATE Loader.load_module is deprecated since Python 3.4. Use Loader.exec_module instead:
>>> import types
>>> import importlib.machinery
>>> loader = importlib.machinery.SourceFileLoader('a_b', '/tmp/a-b.txt')
>>> mod = types.ModuleType(loader.name)
>>> loader.exec_module(mod)
>>> mod
<module 'a_b'>
>>> import importlib.machinery
>>> import importlib.util
>>> loader = importlib.machinery.SourceFileLoader('a_b', '/tmp/a-b.txt')
>>> spec = importlib.util.spec_from_loader(loader.name, loader)
>>> mod = importlib.util.module_from_spec(spec)
>>> loader.exec_module(mod)
>>> mod
<module 'a_b' from '/tmp/a-b.txt'>

Updated for Python >= 3.8:
Short version:
>>> # https://docs.python.org/3/library/importlib.html#importing-a-source-file-directly
>>> import importlib.util, sys
>>> spec = importlib.util.spec_from_file_location(modname, fname)
>>> module = importlib.util.module_from_spec(spec)
>>> sys.modules[modname] = module
>>> spec.loader.exec_module(module)
Full version:
>>> import importlib.util
>>> import sys
>>> from pathlib import Path
>>> from typing import TYPE_CHECKING
>>>
>>>
>>> if TYPE_CHECKING:
... import types
...
...
>>> def import_source_file(fname: str | Path, modname: str) -> "types.ModuleType":
... """
... Import a Python source file and return the loaded module.
... Args:
... fname: The full path to the source file. It may container characters like `.`
... or `-`.
... modname: The name for the loaded module. It may contain `.` and even characters
... that would normally not be allowed (e.g., `-`).
... Return:
... The imported module
... Raises:
... ImportError: If the file cannot be imported (e.g, if it's not a `.py` file or if
... it does not exist).
... Exception: Any exception that is raised while executing the module (e.g.,
... :exc:`SyntaxError). These are errors made by the author of the module!
... """
... # https://docs.python.org/3/library/importlib.html#importing-a-source-file-directly
... spec = importlib.util.spec_from_file_location(modname, fname)
... if spec is None:
... raise ImportError(f"Could not load spec for module '{modname}' at: {fname}")
... module = importlib.util.module_from_spec(spec)
... sys.modules[modname] = module
... try:
... spec.loader.exec_module(module)
... except FileNotFoundError as e:
... raise ImportError(f"{e.strerror}: {fname}") from e
... return module
...
>>> import_source_file(Path("/tmp/my_mod.py"), "my_mod")
<module 'my_mod' from '/tmp/my_mod.py'>
Original answer for Python 3.5 and 3.6
Shorter version of #falsetru 's solution:
>>> import importlib.util
>>> spec = importlib.util.spec_from_file_location('a_b', '/tmp/a-b.py')
>>> mod = importlib.util.module_from_spec(spec)
>>> spec.loader.exec_module(mod)
>>> mod
<module 'a_b' from '/tmp/a-b.txt'>
I tested it with Python 3.5 and 3.6.
According to the comments, it does not work with arbitrary file extensions.

Similar to #falsetru but for Python 3.5+ and accounting for what the importlib doc states on using importlib.util.module_from_spec over types.ModuleType:
This function [importlib.util.module_from_spec] 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.
We are able to import any file with importlib alone by modifying the importlib.machinery.SOURCE_SUFFIXES list.
import importlib
importlib.machinery.SOURCE_SUFFIXES.append('') # empty string to allow any file
spec = importlib.util.spec_from_file_location(module_name, file_path)
module = importlib.util.module_from_spec(spec)
spec.loader.exec_module(module)
# if desired: importlib.machinery.SOURCE_SUFFIXES.pop()

importlib helper function
Here is a convenient, ready-to-use helper to replace imp, with an example. The technique is the same as that of https://stackoverflow.com/a/19011259/895245 , this is just providing a more convenient function.
main.py
#!/usr/bin/env python3
import os
import importlib
def import_path(path):
module_name = os.path.basename(path).replace('-', '_')
spec = importlib.util.spec_from_loader(
module_name,
importlib.machinery.SourceFileLoader(module_name, path)
)
module = importlib.util.module_from_spec(spec)
spec.loader.exec_module(module)
sys.modules[module_name] = module
return module
notmain = import_path('not-main')
print(notmain)
print(notmain.x)
not-main
x = 1
Run:
python3 main.py
Output:
<module 'not_main' from 'not-main'>
1
I replace - with _ because my importable Python executables without extension have hyphens as in my-cmd. This is not mandatory, but produces better module names like my_cmd.
This pattern is also mentioned in the docs at: https://docs.python.org/3.7/library/importlib.html#importing-a-source-file-directly
I ended up moving to it because after updating to Python 3.7, import imp prints:
DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses
and I don't know how to turn that off, this was asked at:
The imp module is deprecated
How to ignore deprecation warnings in Python
Tested in Python 3.7.3.

after many failure solutions this one works for me
def _import(func,*args):
import os
from importlib import util
module_name = "my_module"
BASE_DIR = "wanted module directory path"
path = os.path.join(BASE_DIR,module_name)
spec = util.spec_from_file_location(func, path)
mod = util.module_from_spec(spec)
spec.loader.exec_module(mod)
return getattr(mod,func)(*args)
and to call it just write the function name and it's parameters _import("function",*args)