如何用Context Manager实现支持嵌套的Indenter类以生成指定缩进输出？

To implement the nested indentation behavior you need, create a context manager that tracks the current indentation level—increasing it when entering a with block and decreasing it when exiting. Here's the working code:

class Indenter:
    def __init__(self):
        self.level = -1  # Start at -1 so first enter sets level to 0
    
    def __enter__(self):
        self.level += 1
        return self
    
    def __exit__(self, exc_type, exc_val, exc_tb):
        self.level -= 1
    
    def print(self, text):
        print('   ' * self.level + text)

How It Works: #

• Indentation Tracking: The level instance variable keeps track of nested depth. Starting at -1 ensures the top-level with block sets the level to 0 (no indentation for the first print).
• Context Manager Methods:
  • __enter__: Increments the level every time a with block is entered, and returns the instance itself to allow nested use of the same indent object.
  • __exit__: Decrements the level when exiting a with block, reverting to the previous indentation depth.
• Print Method: Prepends 3 * level spaces to the input text, creating the nested indentation effect matching your desired output.

Test Output: #

Running your provided code with this Indenter class will produce:

Hi
   Talk is Cheap!
      Show me the Code...
Torvalds

内容的提问来源于stack exchange，提问作者Mohammad Ali Soltan Hosseini