python star模块 python model模块

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jiecho 2023-06-16 20:39:02

文章标签 python star模块 python 实例化 Python bc 文章分类 Python 后端开发

前言

python中的模块定义与调用，趁着国庆假期空闲，深入研究研究！

提示：以下是本篇文章正文内容，下面案例可供参考

一、模块是什么？

Python 模块(Module)，是一个 Python 文件，以 .py 结尾，包含了 Python 对象定义和Python语句。
模块让你能够有逻辑地组织你的 Python 代码段。
把相关的代码分配到一个模块里能让你的代码更好用，更易懂。
模块能定义函数，类和变量，模块里也能包含可执行的代码。

二、关于模块的几个知识点

1.模块导入

import module_name
from module_name import def
from module_name import * （其中 *号，导入模块定义的__all__常量中的API），举个例子，如下：
calendar模块定义， calendar.py：

__all__ = ["IllegalMonthError", "IllegalWeekdayError", "setfirstweekday",
           "firstweekday", "isleap", "leapdays", "weekday", "monthrange",
           "monthcalendar", "prmonth", "month", "prcal", "calendar",
           "timegm", "month_name", "month_abbr", "day_name", "day_abbr"]

calendar_demo.py中导入模块，就会导入 __all__中所有方法：

# -*- coding:utf-8 -*-

from calendar import *

print(monthcalendar(2021, 10))

2.模块方法

同样看calendar模块定义，calendar.py：

mdays = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]

def isleap(year):
    """Return True for leap years, False for non-leap years."""
    return year % 4 == 0 and (year % 100 != 0 or year % 400 == 0)
    
def weekday(year, month, day):
    """Return weekday (0-6 ~ Mon-Sun) for year (1970-...), month (1-12),
       day (1-31)."""
    return datetime.date(year, month, day).weekday()

调用calendar模块方法与常量，calendar_demo.py：

# -*- coding:utf-8 -*-

import calendar

mdays = calendar.mdays #读取calendar模块中定义的常量mdays
print(mdays)

d_isleap = calendar.isleap(2021) #判断瑞年
print(d_isleap)

d_weekday =  calendar.weekday(2021, 10, 6) #返回星期几
print(d_weekday)#Return weekday (0-6 ~ Mon-Sun)

3.类普通方法调用

同样看calendar模块定义，calendar.py：

class Calendar(object):
    """
    Base calendar class. This class doesn't do any formatting. It simply
    provides data to subclasses.
    """

    def __init__(self, firstweekday=0):
        self.firstweekday = firstweekday # 0 = Monday, 6 = Sunday
    
    def monthdatescalendar(self, year, month):
        """
        Return a matrix (list of lists) representing a month's calendar.
        Each row represents a week; week entries are datetime.date values.
        """
        dates = list(self.itermonthdates(year, month))
        return [ dates[i:i+7] for i in range(0, len(dates), 7) ]    

class TextCalendar(Calendar):
    """
    Subclass of Calendar that outputs a calendar as a simple plain text
    similar to the UNIX program cal.
    """

调用calendar模块方法与常量，calendar_demo.py：

# -*- coding:utf-8 -*-

import calendar

print("--------------------------------------------------")
calendar_obj = calendar.Calendar(firstweekday=1)
ca = calendar_obj.monthdatescalendar(2021, 10) #返回当月日历
print(ca)

print("*************************************************")
textCalendar_obj = calendar.TextCalendar(firstweekday=0)
ca_text = textCalendar_obj.monthdatescalendar(2021, 10) #返回当月日历
print(ca_text)

4.类方法调用，@classmethod修饰方法

同样看datetime模块定义，datetime.py：

class date:
    """Concrete date type.

    Constructors:

    __new__()
    fromtimestamp()
    today()
    fromordinal()

    Operators:

    __repr__, __str__
    __eq__, __le__, __lt__, __ge__, __gt__, __hash__
    __add__, __radd__, __sub__ (add/radd only with timedelta arg)

    Methods:

    timetuple()
    toordinal()
    weekday()
    isoweekday(), isocalendar(), isoformat()
    ctime()
    strftime()

    Properties (readonly):
    year, month, day
    """
    __slots__ = '_year', '_month', '_day', '_hashcode'

    def __new__(cls, year, month=None, day=None):
        """Constructor.

        Arguments:

        year, month, day (required, base 1)
        """
        if month is None and isinstance(year, bytes) and len(year) == 4 and \
                1 <= year[2] <= 12:
            # Pickle support
            self = object.__new__(cls)
            self.__setstate(year)
            self._hashcode = -1
            return self
        year, month, day = _check_date_fields(year, month, day)
        self = object.__new__(cls)
        self._year = year
        self._month = month
        self._day = day
        self._hashcode = -1
        return self

    # Additional constructors
	
    @classmethod
    def fromtimestamp(cls, t):
        "Construct a date from a POSIX timestamp (like time.time())."
        y, m, d, hh, mm, ss, weekday, jday, dst = _time.localtime(t)
        return cls(y, m, d)

    @classmethod
    def today(cls):
        "Construct a date from time.time()."
        t = _time.time()
        return cls.fromtimestamp(t)

调用datetime模块中date类中方法，datetime_date_demo.py：

# -*- coding:utf-8 -*-

from datetime import date

d_new = date(2021, 10, 6) #根据date类中 __new__方法，实例化一个date对象
print(d_new)

#调用@classmethod（类方法），不用实例化对象，可直接调用方法
d_fromtimestamp = date.fromtimestamp(1000) #以UniX元年开始，转换时间戳为对应日期
print(d_fromtimestamp)

d_today = date.today() #返回今天日期
print(d_today)

5.模块中实例化的类方法调用

同样看calendar模块定义，calendar.py：

__all__ = ["IllegalMonthError", "IllegalWeekdayError", "setfirstweekday",
           "firstweekday", "isleap", "leapdays", "weekday", "monthrange",
           "monthcalendar", "prmonth", "month", "prcal", "calendar",
           "timegm", "month_name", "month_abbr", "day_name", "day_abbr"]
           
class Calendar(object):
    """
    Base calendar class. This class doesn't do any formatting. It simply
    provides data to subclasses.
    """

    def __init__(self, firstweekday=0):
        self.firstweekday = firstweekday # 0 = Monday, 6 = Sunday       
    
    def monthdatescalendar(self, year, month):
        """
        Return a matrix (list of lists) representing a month's calendar.
        Each row represents a week; week entries are datetime.date values.
        """
        dates = list(self.itermonthdates(year, month))
        return [ dates[i:i+7] for i in range(0, len(dates), 7) ]  
        
class TextCalendar(Calendar):
    """
    Subclass of Calendar that outputs a calendar as a simple plain text
    similar to the UNIX program cal.
    """

# Support for old module level interface
c = TextCalendar()
monthcalendar = c.monthdayscalendar

调用calendar模块中方法，calendar_demo.py：

# -*- coding:utf-8 -*-

import calendar

#普通调用方法：先实例化，再调用类方法
ca_text_obj = calendar.TextCalendar(firstweekday=0)
ca_text = ca_text_obj.monthdayscalendar(2021, 10)
print(ca_text)

#既然在模块中已经实例化，直接使用如下方式调用
ca_text_instantiate = calendar.monthcalendar(2021, 10)
print(ca_text_instantiate)

特别注意如上定义方式：直接在模块中实例化类，将类赋值给一个属性，并将该属性放在__all__中导入，当然如上还有类的集成等

6.模块中@property方法

同样看datetime模块定义，datetime.py：

class date:
    """Concrete date type.

    Constructors:

    __new__()
    fromtimestamp()
    today()
    fromordinal()

    Operators:

    __repr__, __str__
    __eq__, __le__, __lt__, __ge__, __gt__, __hash__
    __add__, __radd__, __sub__ (add/radd only with timedelta arg)

    Methods:

    timetuple()
    toordinal()
    weekday()
    isoweekday(), isocalendar(), isoformat()
    ctime()
    strftime()

    Properties (readonly):
    year, month, day
    """
    __slots__ = '_year', '_month', '_day', '_hashcode'

    def __new__(cls, year, month=None, day=None):
        """Constructor.

        Arguments:

        year, month, day (required, base 1)
        """
        if month is None and isinstance(year, bytes) and len(year) == 4 and \
                1 <= year[2] <= 12:
            # Pickle support
            self = object.__new__(cls)
            self.__setstate(year)
            self._hashcode = -1
            return self
        year, month, day = _check_date_fields(year, month, day)
        self = object.__new__(cls)
        self._year = year
        self._month = month
        self._day = day
        self._hashcode = -1
        return self
   
    # Read-only field accessors
    @property
    def year(self):
        """year (1-9999)"""
        return self._year

    @property
    def month(self):
        """month (1-12)"""
        return self._month

    @property
    def day(self):

调用datetime模块中方法，datetime_date_demo.py：

# -*- coding:utf-8 -*-

import datetime

d_new = datetime.date.today() #实例化一个date
print(d_new)

#私有访问器
d_new_year = d_new.year #方法通过属性方式访问， 返回当前日期年份
print(d_new_year)

d_new_month = d_new.month #方法通过属性方式访问， 返回当前日期月份
print(d_new_month)

d_new_day = d_new.day #方法通过属性方式访问， 返回当前日期日
print(d_new_day)