如何导入自定义Python包并访问markets包内模块？

Let's work through this step by step to get you accessing the Player class properly. The key issue here is that importing the top-level markets package doesn't automatically pull in all its internal modules/classes unless you explicitly set that up. Here's what to check and fix:

1. First, Confirm Your Directory Structure #

Make sure your markets package is organized correctly under ~/python_lib. It should look something like this (adjust based on where Player is actually defined):

~/python_lib/
└── markets/
    ├── __init__.py
    └── [your_module_name].py  # e.g., players.py, where the Player class lives

If Player is nested deeper (like markets/core/players.py), note that path too—we'll need it for imports.

2. Check Your __init__.py Content #

If your __init__.py is empty (or doesn't include imports for Player), importing markets only loads the package itself, not the internal classes. You have two options here:

Option A: Update __init__.py to Expose Player #

Add a line to markets/__init__.py that imports Player from its module. For example, if Player is in players.py:

# markets/__init__.py
from .players import Player

Now, when you run import markets in IPython, you can create a Player instance with:

p = markets.Player()

Option B: Import Directly from the Submodule #

If you don't want to modify __init__.py, just import Player directly from its module. Using the same players.py example:

from markets.players import Player
# Now this works:
p = Player()

Or if you prefer to keep the module namespace:

import markets.players
p = markets.players.Player()

3. Verify the Import Worked #

After importing markets, run dir(markets) in IPython. You should see Player (if you used Option A) or the name of your submodule (like players) listed. If not, double-check:

• That ~/python_lib is indeed in sys.path (you said you verified this, but a quick print(sys.path) won't hurt)
• That there are no other markets packages/modules in your sys.path that might be overriding yours
• That the module containing Player has no syntax errors (try running python ~/python_lib/markets/players.py to check for errors)

4. Common Pitfall to Avoid #

Don't confuse importing the package with importing its contents. A bare import markets only gives you access to what's explicitly defined in __init__.py—it won't magically load all submodules. That's why you weren't getting an error on import markets, but couldn't access Player directly.

内容的提问来源于stack exchange，提问作者James A. Foster