Python __import__() Function
Python3 Built-in Functions__import__()It is a built-in function in Python used for dynamically importing modules.
__import__()YesimportIt is the underlying implementation of the import statement, allowing modules to be dynamically imported at runtime. It is very useful for scenarios such as plugin systems and lazy loading.
Word Definitions： __import__ 是 Python 的内置导入函数。
Basic Syntax and Parameters
Syntax Format
__import__(name, globals=None, locals=None, fromlist=(), level=0)
Parameter Description
- Parameter name：
- Type: String
- Description: The name of the module to import.
- Parameter fromlist(Optional):
- Type: Tuple
- Description: A list of submodules or attributes to import from the module.
Function Description
- Return Value: Returns the imported module object.
Examples
Example 1: Basic Usage
Example
# Dynamically import module
os = __import__('os')
print(os.getcwd()) # Output: current working directory
# Import submodule
requests = __import__('collections', fromlist=['Counter'])
print(requests.Counter) # Output: <class 'collections.Counter'>
os = __import__('os')
print(os.getcwd()) # Output: current working directory
# Import submodule
requests = __import__('collections', fromlist=['Counter'])
print(requests.Counter) # Output: <class 'collections.Counter'>
Output:
Ways to import modules.
Example 2: Dynamic Import
Example
# Import module based on string
module_name = "json"
mod = __import__(module_name)
print(mod.dumps({"key": "value"})) # Output: {"key": "value"}
# Dynamically import multiple modules
modules = ['math', 'random', 'datetime']
for name in modules:
mod = __import__(name)
print(f"{name}: {mod.__name__}")
# Lazy import (on-demand loading)
def get_module(mod_name):
return __import__(mod_name)
math_mod = get_module('math')
print(math_mod.sqrt(16)) # Output: 4.0
module_name = "json"
mod = __import__(module_name)
print(mod.dumps({"key": "value"})) # Output: {"key": "value"}
# Dynamically import multiple modules
modules = ['math', 'random', 'datetime']
for name in modules:
mod = __import__(name)
print(f"{name}: {mod.__name__}")
# Lazy import (on-demand loading)
def get_module(mod_name):
return __import__(mod_name)
math_mod = get_module('math')
print(math_mod.sqrt(16)) # Output: 4.0
Output:
Dynamic import has various uses in practical applications.
__import__()It is the core of Python's dynamic import mechanism.
Other Extensions