Python __init__中self属性可打印但无法正常使用问题求助

Hey Roger, let's work through this frustrating issue—nothing's worse than code that worked perfectly one day and breaks the next without you touching it. Let's break down possible causes and fixes based on the code snippet you shared:

First, let's start with the obvious red flags in your code and then move to the "suddenly broken" angle:

1. Fix the Typo in Your Initialization #

Looking at the end of your __init__ method, you have self.update_canva...—that's a partial, misspelled call to update_canvas() (you're missing the final s and parentheses). If you never actually trigger this method on initialization, your widget won't render the text you set, even if self.text prints correctly. That's probably the first thing to fix:

# Replace the partial line with:
self.update_canvas()

2. Check for Parent Class Conflicts #

Your BorderWidgetWithLabel inherits from BorderWidget—it’s possible the parent class is interfering with your self.text attribute:

• Does BorderWidget also define a text attribute in its own __init__? If it does, it might be overwriting your value after you call super().__init__().
• Try reordering your code to capture the text parameter before calling the parent initializer:

  class BorderWidgetWithLabel(BorderWidget):
      def __init__(self, **kwargs):
          # Grab text first before parent class processes kwargs
          self.text = kwargs.pop('text', ' ')
          super(BorderWidgetWithLabel, self).__init__(**kwargs)
          print(self.text)  # Should still print correctly
          # Rest of your code...
          self.update_canvas()
  

This ensures your text value isn’t clobbered by any logic in the parent class.

3. Verify update_canvas Uses self.text Correctly #

You said self.text prints but doesn’t work—double-check your update_canvas method:

• Are you accidentally using a local text variable instead of self.text?
• Is there a typo in how you reference self.text (e.g., self.txt instead of self.text)?
• Add a print(self.text) at the start of update_canvas to confirm the value is still accessible when the method runs.

4. Rule Out Environment Changes #

Since you didn’t modify the code but it stopped working, the issue might be external:

• Did your dependency versions update? For example, if this is a Kivy widget (common with bind(pos/size) and canvas logic), a recent Kivy update could have changed how parent widgets handle attributes like text.
• Try rolling back to the version of your dependencies that was working when the code ran smoothly.
• If BorderWidget is a custom class you or your team maintains, check if someone else modified its code recently.

Start with the typo fix first—that’s the most straightforward culprit. If that doesn’t resolve it, work through the parent class and environment checks. Sometimes "suddenly broken" code is just a tiny overlooked detail or a silent dependency update.

内容的提问来源于stack exchange，提问作者Roger