\documentclass[10pt,a4paper]{article}

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\usepackage{multicol}           % Allows multicols in tables
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%\usepackage{opensans}          % Can't make this work so far. Shame. Would be lovely.
\usepackage[normalem]{ulem}     % For underlining links
% Most of the following are not required for the majority
% of cheat sheets but are needed for some symbol support.
\usepackage{amsmath}            % Symbols
\usepackage{MnSymbol}           % Symbols
\usepackage{wasysym}            % Symbols
%\usepackage[english,german,french,spanish,italian]{babel}              % Languages

% Document Info
\author{cgeeeeh}
\pdfinfo{
  /Title (oop.pdf)
  /Creator (Cheatography)
  /Author (cgeeeeh)
  /Subject (OOP Cheat Sheet)
}

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\newcommand{\SetRowColor}[1]{\noalign{\gdef\RowColorName{#1}}\rowcolor{\RowColorName}} % Shortcut for row colour
\newcommand{\mymulticolumn}[3]{\multicolumn{#1}{>{\columncolor{\RowColorName}}#2}{#3}} % For coloured multi-cols
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% Font and Colours
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\color{TextColor}

% Header and Footer
\pagestyle{fancy}
\fancyhead{} % Set header to blank
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\fancyhead[L]{
\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{C}
    \SetRowColor{DarkBackground}
    \vspace{-7pt}
    {\parbox{\dimexpr\textwidth-2\fboxsep\relax}{\noindent
        \hspace*{-6pt}\includegraphics[width=5.8cm]{/web/www.cheatography.com/public/images/cheatography_logo.pdf}}
    }
\end{tabulary}
\columnbreak
\begin{tabulary}{11cm}{L}
    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{OOP Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{cgeeeeh} via \textcolor{DarkBackground}{\uline{cheatography.com/191000/cs/39808/}}}
\end{tabulary}
\end{multicols}}

\fancyfoot[L]{ \footnotesize
\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{LL}
  \SetRowColor{FootBackground}
  \mymulticolumn{2}{p{5.377cm}}{\bf\textcolor{white}{Cheatographer}}  \\
  \vspace{-2pt}cgeeeeh \\
  \uline{cheatography.com/cgeeeeh} \\
  \end{tabulary}
\vfill
\columnbreak
\begin{tabulary}{5.8cm}{L}
  \SetRowColor{FootBackground}
  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Cheat Sheet}}  \\
   \vspace{-2pt}Not Yet Published.\\
   Updated 7th August, 2023.\\
   Page {\thepage} of \pageref{LastPage}.
\end{tabulary}
\vfill
\columnbreak
\begin{tabulary}{5.8cm}{L}
  \SetRowColor{FootBackground}
  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Sponsor}}  \\
  \SetRowColor{white}
  \vspace{-5pt}
  %\includegraphics[width=48px,height=48px]{dave.jpeg}
  Measure your website readability!\\
  www.readability-score.com
\end{tabulary}
\end{multicols}}




\begin{document}
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% from this page to resize cheat sheet text:
% www.emerson.emory.edu/services/latex/latex_169.html
\footnotesize % Small font.

\begin{multicols*}{2}

\begin{tabularx}{8.4cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{class}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{\seqsplit{\#类的名字应该用大写字母} \newline class Employee: \newline   \#给一些定义 \newline   """ define a class for all employee \newline instances in a company """ \newline   \#没啥内容就写pass \newline   pass \newline  \newline \#创建一个实体 \newline variable\_name = Employee()} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{Attributes}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{instance attributes \seqsplit{是每个实体都有自己的} \newline \# Provide attributes and assign values to the instances \newline emp1.firstName = "Maria" \newline emp1.lastName = "Rena" \newline emp1.basicSalary = 12000 \newline emp1.allowance = 5000 \newline  \newline class attributes belong to the class itself, and are thus shared among all instances of the class \newline 如果先声明instant \seqsplit{attribute，再声明class} \seqsplit{attribute。那不会覆盖原来的instant} attribute。 \newline 但如果原来在类里声明了一个类attribute，在后面再修改，那原来的值确实会被覆盖 \newline  \newline obj.\_\_dict\_\_返回【实体】和它的所有方法 \newline class.\_\_dict\_\_返回【类】的所有方法和属性} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{Methods}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{instant method是自定义的 \newline class Employee: \newline   bonusPercent = 0.2 \newline   \# Define an instance method that takes no arguments \newline   def calculateBonus(self): \newline     return self.salary * Employee.bonusPercent \newline  \newline 如何更改bonusPercent的默认值？用类的调用来改 \newline Employee.bonusPercent=0.3 \newline  \newline Constructor \& Destructor Method \seqsplit{是内置的建立和销毁函数} \newline \_\_init\_\_，\_\_del\_\_，\_\_str\_\_} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{\seqsplit{使用默认参数初始化实例}}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{\seqsplit{\#这段代码有条件才执行，如果不执行的话这个实例四个attribute都不会有} \newline def \_\_init\_\_ (self, first = None, last = None, salary = None, allowances = None): \newline   if first!= None and last!= None and salary!= None and allowances!= None: \newline     self.firstName = first \newline     self.lastName = last \newline     self.salary = salary \newline     self.allowances = allowances \newline     print("Object initialized with supplied values")} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{写入和加载obj}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{import \_pickle as cpickle \newline class stock: \newline   def \_\_init\_\_(self, name, lots): \newline   self.name = name \newline   self.lots = lots \newline   def \_\_str\_\_(self): \newline     return f'\{self.name\}=\textgreater{}\{self.lots\}' \newline  \newline \#写入 \newline s1 = stock("Apple",1500) \newline s2 = stock("Google",2000) \newline with open("s1.obj", "wb") as f: \newline cpickle.dump(s1/{[}s1,s2{]}, f) \newline  \newline \#加载 \newline with open("s1.obj", "rb") as f: \newline   s1 = cpickle.load(f) \newline   print(s1) \newline with open("ss.obj", "rb") as f: \newline   data = cpickle.load(f) \newline   for each in data: \newline     print(each)} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{\seqsplit{self.variable和class.variable的区别}}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{class employee: \newline   count=5 \newline   def \_\_init\_\_(self,x): \newline     self.x=x \newline     self.count=self.count+1 \newline     print ("this method is executed") \newline     print (self.count) \newline     print (employee.count) \newline  \newline emp1=employee("John") \newline emp1.count+=1 \newline print(emp1.count) \newline print(employee.count) \newline  \newline 结果是6，5，7，5。self.variable显示的是这个obj自己当前的值，class.variable显示的是他们共用的初始值} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{JSON \seqsplit{data（json，dict和obj可以互相转化）}}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{\seqsplit{\#把obj放进json再取出来} \newline import json \newline from json import JSONEncoder \newline  \newline class stock(object): \newline   def \_\_init\_\_(self, name, lots): \newline     self.name = name \newline     self.lots = lots \newline   def \_\_str\_\_(self): \newline     return f'\{self.name\}=\textgreater{}\{self.lots\}' \newline  \newline class \seqsplit{StockEncoder(JSONEncoder):} \newline   def default(self, o): \newline   return o.\_\_dict\_\_ \newline  \newline s1 = stock("Apple",1500) \newline  \newline \# encode Object it \newline s1Json = json.dumps(s1, cls=StockEncoder, indent=4) \newline ''' \newline json.loads() method can be used to parse a valid JSON string and convert it into a Python Dictionary. \newline ''' \newline resultDict = json.loads(s1Json) \newline s1Obj = stock({\bf{resultDict) \newline  \newline \#json data写入/存储 \newline with \seqsplit{open("stockPrettyPrint.json"}, "w") as write\_file: \newline   json.dump(s1, write\_file,cls=StockEncoder, indent=4) \newline with \seqsplit{open("stockPrettyPrint.json"}, "r") as read\_file: \newline   s = json.load(read\_file) \newline   PrettyJson = json.dumps(s, indent=4, separators=(',', ': '), sort\_keys=True) \newline  \newline \#Json, Dictionary, object \newline import json \newline from json import JSONEncoder \newline  \newline class stock(object): \newline   def \_\_init\_\_(self, name, lots): \newline     self.name = name \newline     self.lots = lots \newline   def \_\_str\_\_(self): \newline     return f'\{self.name\}=\textgreater{}\{self.lots\}' \newline  \newline class \seqsplit{StockEncoder(JSONEncoder):} \newline   def default(self, o): \newline     return o.\_\_dict\_\_ \newline   def StockDecoder(obj): \newline     if '\_\_type\_\_' in obj and obj{[}'\_\_type\_\_'{]} =='stock': \newline       return stock(obj{[}'name'{]}, obj{[}'lots'{]}) \newline     return obj \newline  \newline s2Obj = json.loads('\{"\_\_type\_\_": "stock", "lots":2000, "name": "Google"\}', \seqsplit{object\_hook=StockDecoder)} \newline  \newline with \seqsplit{open("stockPrettyPrint.json"}, "w") as write\_file: \newline   json.dump({[}s2Obj{]}, write\_file,cls=StockEncoder, indent=4)) \newline with \seqsplit{open("stockPrettyPrint.json"}, "r") as read\_file: \newline   print("Read JSON file") \newline   s = json.load(read\_file) \newline   for each in s: \newline     each = stock(}}each) \newline     print(each)} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{JSON \seqsplit{data（json，dict和obj是可以互转）}}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{\seqsplit{\#把obj放进json再取出来} \newline import json \newline from json import JSONEncoder \newline  \newline class stock(object): \newline   def \_\_init\_\_(self, name, lots): \newline     self.name = name \newline     self.lots = lots \newline   def \_\_str\_\_(self): \newline     return f'\{self.name\}=\textgreater{}\{self.lots\}' \newline  \newline class \seqsplit{StockEncoder(JSONEncoder):} \newline   def default(self, o): \newline   return o.\_\_dict\_\_ \newline  \newline s1 = stock("Apple",1500) \newline  \newline \# encode Object it \newline s1Json = json.dumps(s1, cls=StockEncoder, indent=4) \newline ''' \newline json.loads() method can be used to parse a valid JSON string and convert it into a Python Dictionary. \newline ''' \newline resultDict = json.loads(s1Json) \newline s1Obj = stock({\bf{resultDict) \newline  \newline \#json data写入/存储 \newline with \seqsplit{open("stockPrettyPrint.json"}, "w") as write\_file: \newline   json.dump(s1, write\_file,cls=StockEncoder, indent=4) \newline with \seqsplit{open("stockPrettyPrint.json"}, "r") as read\_file: \newline   s = json.load(read\_file) \newline   PrettyJson = json.dumps(s, indent=4, separators=(',', ': '), sort\_keys=True) \newline  \newline \#Json, Dictionary, object \newline import json \newline from json import JSONEncoder \newline  \newline class stock(object): \newline   def \_\_init\_\_(self, name, lots): \newline     self.name = name \newline     self.lots = lots \newline   def \_\_str\_\_(self): \newline     return f'\{self.name\}=\textgreater{}\{self.lots\}' \newline  \newline class \seqsplit{StockEncoder(JSONEncoder):} \newline   def default(self, o): \newline     return o.\_\_dict\_\_ \newline   def StockDecoder(obj): \newline     if '\_\_type\_\_' in obj and obj{[}'\_\_type\_\_'{]} =='stock': \newline       return stock(obj{[}'name'{]}, obj{[}'lots'{]}) \newline     return obj \newline  \newline s2Obj = json.loads('\{"\_\_type\_\_": "stock", "lots":2000, "name": "Google"\}', \seqsplit{object\_hook=StockDecoder)} \newline  \newline with \seqsplit{open("stockPrettyPrint.json"}, "w") as write\_file: \newline   json.dump({[}s2Obj{]}, write\_file,cls=StockEncoder, indent=4)) \newline with \seqsplit{open("stockPrettyPrint.json"}, "r") as read\_file: \newline   print("Read JSON file") \newline   s = json.load(read\_file) \newline   for each in s: \newline     each = stock(}}each) \newline     print(each)} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}


% That's all folks
\end{multicols*}

\end{document}