在Python 3中延迟加载文件的推荐方法是什么?
我已经通过Python 2代码中的copy-past构建了这个函数
def get_command(self, ctx, cmd_name):
ns = {}
fn = os.path.join(cmd_folder, 'cmd_{}.py'.format(cmd_name))
with open(fn) as f:
code = compile(f.read(), str(fn), 'exec')
eval(code, ns, ns)
return ns['cli']
但我不确定这是不是正确的方法。它使用compile
和eval
修改
使用import
之后:
def get_command(self, ctx, cmd_name):
cmd_mod = import_module('{}.cmd_{}'.format(cmd_folder, cmd_name))
这是结果:
File "aws_iam_cli/cli.py", line 23, in get_command
cmd_mod = import_module('{}.cmd_{}'.format(cmd_folder, cmd_name))
File "/Users/salvatoremazzarino/awsiam/venv/lib/python3.6/importlib/__init__.py", line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 994, in _gcd_import
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "<frozen importlib._bootstrap>", line 941, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap>", line 994, in _gcd_import
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "<frozen importlib._bootstrap>", line 953, in _find_and_load_unlocked
ModuleNotFoundError: No module named '/Users/salvatoremazzarino/awsiam/aws_iam_cli/commands'
编辑#2:
def get_command(self, ctx, cmd_name):
mod = import_module('aws_iam_cli.commands.cmd_{}'
.format(cmd_name))
return mod.cli
和错误:
File "/Users/salvatoremazzarino/awsiam/venv/lib/python3.6/importlib/__init__.py", line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 994, in _gcd_import
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "<frozen importlib._bootstrap>", line 941, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap>", line 994, in _gcd_import
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "<frozen importlib._bootstrap>", line 941, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap>", line 994, in _gcd_import
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "<frozen importlib._bootstrap>", line 953, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'aws_iam_cli'
这是目录树:
├── aws_iam_cli
│ ├── __init__.py
│ ├── cli.py
│ ├── commands
│ │ ├── __init__.py
│ │ ├── __pycache__
│ │ └── cmd_dump.py
│ └── provider
│ ├── __init__.py
│ ├── policy.py
│ └── role.py
内部命令我有一个模块,我在该模块内部调用:
from aws_iam_cli.provider.role import fetch_roles
答案 0 :(得分:2)
您可以使用importlib.import_module在运行时动态加载模块。例如:
from importlib import import_module
# load module
pckg_name = 'commands' # I assume all your commands are in this pckg
cmd_mod = import_module('{}.cmd_{}'.format(pckg_name, cmd_name))
# run command (I'm assuming the module contains a function with the 'cmd_name')
cmd_mod.cmd_name()
我认为这种方法会更清洁,更安全,并且应该与你正在做的事情一起工作。