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\documentclass[14pt,compress,aspectratio=169]{beamer}
\input{macros.tex}
\title[OOP: Miscellaneous]{Advanced Python}
\subtitle{Object Oriented Programming: miscellaneous}
\author[FOSSEE] {The FOSSEE Group}
\institute[IIT Bombay] {Department of Aerospace Engineering\\IIT Bombay}
\date[] {Mumbai, India}
\begin{document}
\begin{frame}
\titlepage
\end{frame}
\begin{frame}
\frametitle{Recap}
\begin{itemize}
\item Classes for encapsulation
\item Inheritance
\item \py{super,isinstance,issubclass}
\item Containership
\item Class attributes and methods
\vspace*{0.3in}
\item Look at some odds and ends
\end{itemize}
\end{frame}
\begin{frame}[fragile]
\frametitle{More on methods}
\begin{lstlisting}
class A:
def f(self):
print("A.f")
In []: a = A()
In []: a.f()
A.f
In []: A.f(a)
In []: A.f()
\end{lstlisting}
\end{frame}
\begin{frame}[fragile]
\frametitle{More on methods}
\begin{lstlisting}
In []: type(a.f)
Out[]: method
In []: type(A.f)
Out[]: function
\end{lstlisting}
\end{frame}
\begin{frame}[fragile]
\frametitle{Private and public attributes}
\begin{itemize}
\item No explicit support
\item In practice, use \py{_attr} for private attributes/methods
\end{itemize}
\begin{lstlisting}
class A:
def __init__(self, x):
self._x = x
def _private_method(self):
pass
\end{lstlisting}
\end{frame}
\begin{frame}[fragile]
\frametitle{Private and public attributes}
\begin{itemize}
\item Access private methods/attributes inside class
\item Avoid access from outside
\end{itemize}
\begin{lstlisting}
In []: a = A()
In []: a._method() # Bad!
In []: a._x # Bad!
\end{lstlisting}
\end{frame}
\begin{frame}[fragile]
\frametitle{Private and public attributes}
\begin{lstlisting}
class B:
def _f(self):
# OK!
return self._x
def func(self):
# Also OK!
return self._f()
\end{lstlisting}
\end{frame}
\begin{frame}
\frametitle{Abstract classes}
\begin{itemize}
\item Used to specify an ``interface''
\item Not meant to instantiate but subclass
\item Useful to specify behavior
\end{itemize}
\end{frame}
\begin{frame}[fragile]
\frametitle{Abstract classes}
\begin{lstlisting}
class Abstract:
def func(self):
raise NotImplementedError('override')
class Derived(Abstract):
def func(self):
print("Hello world!")
\end{lstlisting}
\begin{itemize}
\item \py{Derived} is a concrete class
\end{itemize}
\end{frame}
\begin{frame}[fragile]
\frametitle{Modern abstract classes}
\begin{lstlisting}
from abc import ABC, abstractmethod
class Abstract(ABC):
@abstractmethod
def func(self):
pass
\end{lstlisting}
\begin{itemize}
\item More elegant and simple
\item Cannot instantiate \py{Abstract}
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{Summary}
\begin{itemize}
\item Understanding methods a bit better
\item Private/public methods/attributes
\item Abstract and concrete classes
\item Using the \py{abc} module
\end{itemize}
\end{frame}
\end{document}
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