题目描述

Python专属 笔记

1. enumerate: `for i, a in enumerate(A)`

2. zip: `for a, b in zip(A, B)`

3. list comprehension `[x for x in a]`

4. generator `(x for x in a)`

5. try/except/else/finally: 

6. not use `None` as the return, try `Exception`

7. `nonlocal`, `global`: The nonlocal statement makes it clear when data is being assigned out of closure into another scope. It’s complementary to the global statement, which indicates that a variable’s assignment should go directly into the module scope. Anyway, try to use warp the function to a `Class`

8. Consider Generators Instead of Returning Lists: reduce memory cost and fit for big data `yield`. Can be simply warped to list by `list(generator)`

9. build up `__iter__()` as a generator in class

10. `*args`: optional arguments; fit for a small number of args

11. `assert` 

12. Keyword arguments: default value, position. Default argument values are evaluated only once per module load, which usually happens when a program starts up.

13. Docstrings: describe the function, then the `args` and  `return`

14. Using `None` for default argument values is especially important when the arguments have a dynamic value.

15. **The * symbol in the argument list indicates the end of positional arguments and the beginning of keyword-only arguments.** [之前没考虑过]

16. `@classmethod` & `@staticmethod`

17. `NotImplementedError`

18. Python only supports a single constructor per class, the `__init__` method.

19. Always use the `super` built-in function to initialize parent classes.

20. Use `@property` to define special behavior when attributes are accessed on your

    objects, if necessary.

21. decorator: for allowing one function to modify another function

    at runtime.

22. `logging` package.

23. `pickle.dump() pickle.load()`

24. represent time: `datetime`  duration: `time.time()`

25. `__init__.py` for path initialization: Once `__init__.py` is present, any other Python files in that directory will be available for import using a path relative to the directory.

26. `pdb`