Python:函数

1 基础

函数的参数传递有以下几个规则：

1. Arguments are passed by automatically assigning objects to local variable names.
2. Assigning to argument names inside a function does not affect the caller.
3. Changing a mutable object argument in a function may impact the caller.
4. Immutable arguments are effectively passed “by value.”
5. Mutable arguments are effectively passed “by pointer.”

2 设计函数

函数的设计及使用有以下几条建议：

• Coupling: use arguments for inputs and return for outputs.
• Coupling: use global variables only when truly necessary.
• Coupling: don’t change mutable arguments unless the caller expects it.
• Cohesion: each function should have a single, unified purpose.
• Size: each function should be relatively small.
• Coupling: avoid changing variables in another module file directly.