Study Group: 巾凡哥出品 品質保證 python 01
import this The Zen of Python, by Tim Peters
Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.
Special cases aren’t special enough to break the rules.
Although practicality beats purity.
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity, refuse the temptation to guess.
There should be one– and preferably only one –obvious way to do it.
Although that way may not be obvious at first unless you’re Dutch.
Now is better than never.
Although never is often better than right now.
If the implementation is hard to explain, it’s a bad idea.
If the implementation is easy to explain, it may be a good idea.
Namespaces are one honking great idea – let’s do more of those!
我最愛的 python
Introductin
- python 2.7 vs. python 3.x
- python 3.0 在 2008發佈
- python 3 上功能有部分無法向下兼容，但也因不向下兼容，python 3的程式碼 才不會太過肥⼤
- 其餘還有諸多差異，可直接參考網路上比較
- python 2.x 維護到 2020年，但⽬前仍有許多運⾏在 python 2.x的系統與程式
- 課程中主要使⽤ python 3.x
Online IDE
Style Guide
-
module_name, package_name, ClassName, method_name, ExceptionName, function_name, GLOBAL_CONSTANT_NAME, global_var_name, instance_var_name, function_parameter_name, local_var_name.
Simple Types: Integer, String, Float, Boolean
x = 10
y = '10'
z = 10.0
a = True
print(type(x), type(y), type(z), type(a))
# <class 'int'> <class 'str'> <class 'float'> <class 'bool'>
Which code line throws the exception?
x = 10
y = '10'
z=20.0
z=20.0
^
IndentationError: unexpected indent
List type
list = [1, 1.0, '1', [1,2,3, [4,5,6]]
help 幫助你看!
>>> list.help()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: type object 'list' has no attribute 'help'
>>> help(print)
Help on built-in function print in module builtins:
print(...)
print(value, ..., sep=' ', end='\n', file=sys.stdout, flush=False)
Prints the values to a stream, or to sys.stdout by default.
Optional keyword arguments:
file: a file-like object (stream); defaults to the current sys.stdout.
sep: string inserted between values, default a space.
end: string appended after the last value, default a newline.
flush: whether to forcibly flush the stream.
>>> help(list)
Help on class list in module builtins:
class list(object)
| list(iterable=(), /)
|
| Built-in mutable sequence.
|
| If no argument is given, the constructor creates a new empty list.
| The argument must be an iterable if specified.
|
| Methods defined here:
|
| __add__(self, value, /)
| Return self+value.
|
| __contains__(self, key, /)
| Return key in self.
|
| __delitem__(self, key, /)
| Delete self[key].
|
| __eq__(self, value, /)
| Return self==value.
|
| __ge__(self, value, /)
| Return self>=value.
|
| __getattribute__(self, name, /)
| Return getattr(self, name).
|
| __getitem__(...)
| x.__getitem__(y) <==> x[y]
|
| __gt__(self, value, /)
| Return self>value.
|
| __iadd__(self, value, /)
| Implement self+=value.
|
| __imul__(self, value, /)
| Implement self*=value.
|
| __init__(self, /, *args, **kwargs)
| Initialize self. See help(type(self)) for accurate signature.
|
| __iter__(self, /)
| Implement iter(self).
|
| __le__(self, value, /)
| Return self<=value.
|
| __len__(self, /)
| Return len(self).
|
| __lt__(self, value, /)
| Return self<value.
|
| __mul__(self, value, /)
| Return self*value.
|
| __ne__(self, value, /)
| Return self!=value.
|
| __repr__(self, /)
| Return repr(self).
|
| __reversed__(self, /)
| Return a reverse iterator over the list.
|
| __rmul__(self, value, /)
| Return value*self.
|
| __setitem__(self, key, value, /)
| Set self[key] to value.
|
| __sizeof__(self, /)
| Return the size of the list in memory, in bytes.
|
| append(self, object, /)
| Append object to the end of the list.
|
| clear(self, /)
| Remove all items from list.
|
| copy(self, /)
| Return a shallow copy of the list.
|
| count(self, value, /)
| Return number of occurrences of value.
|
| extend(self, iterable, /)
| Extend list by appending elements from the iterable.
|
| index(self, value, start=0, stop=9223372036854775807, /)
| Return first index of value.
|
| Raises ValueError if the value is not present.
|
| insert(self, index, object, /)
| Insert object before index.
|
| pop(self, index=-1, /)
| Remove and return item at index (default last).
|
| Raises IndexError if list is empty or index is out of range.
|
| remove(self, value, /)
| Remove first occurrence of value.
|
| Raises ValueError if the value is not present.
|
| reverse(self, /)
| Reverse *IN PLACE*.
|
| sort(self, /, *, key=None, reverse=False)
| Stable sort *IN PLACE*.
|
| ----------------------------------------------------------------------
| Static methods defined here:
|
| __new__(*args, **kwargs) from builtins.type
| Create and return a new object. See help(type) for accurate signature.
|
| ----------------------------------------------------------------------
| Data and other attributes defined here:
|
| __hash__ = None
dir([object]) 回傳參數所有 sttribute
list = [1, 2, 3]
attrs = dir(list)
print( attrs ) # <= show all attributes of the list
# list = [1, 2, 3]
# attrs = dir(list)
# print( attrs ) # <= show all attributes of the list
- dir( builtins ): 所有 built-in functions
快樂蛇蛇命名!!!
| Pattern | Example | Meaning |
|---|---|---|
| Single Leading Underscore | _var | aming convention indicating a name is meant for internal use. Generally not enforced by the Python interpreter (except in wildcard imports) and meant as a hint to the programmer only. |
| Single Trailing Underscore | var_ | Used by convention to avoid naming conflicts with Python keywords. |
| Double Leading Underscore | __var | Triggers name mangling when used in a class context. Enforced by the Python interpreter. |
| Double Leading and Trailing Underscore | __ var __ | Indicates special methods defined by the Python language. Avoid this naming scheme for your own attributes. |
| Single Underscore | _ | Sometimes used as a name for temporary or insignificant variables (“don’t care”). Also: The result of the last expression in a Python REPL. |
name mangling
class Person:
def __init__(self, name):
self.__name = name
self._name = name
class Woman(Person):
def __init__(self, name):
Person.__init__(self, name)
self.__name = name
if __name__ == "__main__":
jack = Person("Jack")
print(jack)
print(dir(jack))
print(jack._name)
print(jack._Person__name)
print("==============")
tina = Woman('tina')
print(dir(tina))
# <__main__.Person object at 0x000001C06E087BE0>
#'_Person__name', '__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', #'__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', '_name']
#Jack
#Jack
#==============
#['_Person__name', '_Woman__name', '__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', #'__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', '_name']
#
繼承好玩
class Person:
def __init__(self, name):
self.__name = name
self._name = name
def speak(self):
print("person: hahaha")
class Woman(Person):
def __init__(self, name):
Person.__init__(self, name)
self.__name = name
def speak(self):
print("====== from woman ========")
Person.speak(self)
print("woman: yayay")
class LittleWoman(Woman):
def __init__(self, name):
Woman.__init__(self, name)
self.__name = name
def speak(self):
Person.speak(self)
Woman.speak(self)
print("little woman: yayay")
if __name__ == "__main__":
little_woman = LittleWoman("Jack")
print(little_woman.speak())
# person: hahaha
# ====== from woman ========
# person: hahaha
# woman: yayay
# little woman: yayay