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Python - Context Managers
摘要：with statement Here is the syntax of the with statement: with expression as var: statements The expression should be a context manager object, or it s
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Python - Built-in Exceptions: Python Exceptions Class Hierarchy
摘要：Figure 20.4: Built-in exceptions The class BaseException is the base class of all the built-in exception classes. From BaseException, four classes nam
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Python - Strategies to handle exceptions in your code
摘要：There are two approaches that can be followed when we want to deal with exceptions that occur due to unusual events: LBYL - Look Before You Leap EAFP
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Python - operator module
摘要：>>> list(map(lambda x, y: x * y, [1,2,3,4], [5,6,7,8])) [5, 12, 21, 32] Here we have called the map function and sent a lambda expression as first arg
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Python - Functional programming
摘要：Functional programming is a programming paradigm in which most of the work in a program is done using pure functions. A pure function is a function wi
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Python - Creating jump tables using lambda functions
摘要：We can place lambda function inside list and dictionary literals. This way we can use lambda expressions to create jump tables. >>> L = [lambda s: s.s
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Python - Lambda expressions as closures
摘要：A closure is a nested function that can access free variables from an enclosing function even after it has finished its execution. We know that, like
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Python - Class Decorators
摘要：We have used functions to decorate functions and to decorate classes. Now, we will see how to define a class as a decorator. At the start of this chap
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Python - Decorating classes
摘要：When we talk about decorating classes, we can either decorate individual methods or we can create a decorator to decorate the whole class. class MyCla
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Python - Decorators
摘要：A decorator is a callable that takes a callable as input and returns a callable. This is the general definition of a decorator. The callable in this d
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Python - Generators
摘要：The task of implementing iterators can be simplified by using generators. We have seen how to create custom iterators using the object-oriented way, i
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Python - itertools Module
摘要：The itertools module contains special functions to create iterators for efficient looping. It has three broad categories of iterators - infinite itera
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Python - Making your class Iterable
摘要：If we want objects of this class to be used in iteration contexts, then they should support the iteration protocol. To make this class iterable, we ca
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Python - Creating your own Iterator
摘要：In our first example, we will create iterable objects, which, when iterated over, will give out cubes of numbers, and these objects will support multi
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Python - Iterator vs Iterable
摘要：There are many built-in functions and methods that return iterables and iterators. Here are a few examples: range() returns an iterable dict.keys() re
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Python - Composition
摘要：class Engine: def __init__(self,power): self.power = power def start(self): self.draw_current() self.spin() self.ignite() def draw_current(self): prin
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Python - Abstract Base classes
摘要：We have seen that if we have to define a group of classes that have similar features and show common behavior, we can define a base class and then inh
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Python - Polymorphism
摘要：The three main features of object-oriented programming are - encapsulation, inheritance and polymorphism. We have seen the first two, now let us see w
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Python - Method Resolution Order (MRO)
摘要：The order in which Python searches for attributes in base classes is called method resolution order(MRO). It gives a linearized path for an inheritanc
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Python - String representation of an instance object
摘要：The magic methods __str__ and __repr__ are used for converting an instance object into a string. The method __str__ is invoked when an instance object
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Python - Properties
摘要：Creating Managed Attributes using properties Properties can be used to create data attributes with special functionality. If you want some extra funct
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Python - Static Methods
摘要：Sometimes we have to write methods that are related to the class but do not need any access to instance or class data for performing their work. These
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Python - Creating alternative initializers using class Methods
摘要：Class methods allow us to define alternative initializers (also known as factory methods) in a class. These methods help us create instance objects fr
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Python - Change current working directory
摘要：os.getcwd() Returns the path of the current working directory os.chdir(path) Changes our current working directory
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Python - Redirecting output of print to a file
摘要：The print function can also be used to write to a file. The output of print, that is by default, sent to the screen can be redirected to an open file.
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Python - File opening modes and buffering
摘要：'r' - read mode(default) 'w' - write mode 'a' - append mode 'x' - exclusive creation We know that the mode 'r' opens an existing file for reading only
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Python - Reloading a module
摘要：Each module is loaded into memory only once during an interpreter session or during a program run, regardless of the number of times it is imported in
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Python - Function Annotations
摘要：def func(s:str, i:int, j:int) -> str: return s[i:j] The parameter s is supposed to be a string, so we place a colon after the parameter name and then
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Python - Arguments and Parameters
摘要：Parameters in Function Definition A. def func(name): Match by position or by name B. def func(name=value): Default argument C. def func(*args): Collec
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Python - Values returned by "and", "or" and "not" operators
摘要：Unlike some other languages, in Python, the logical operators "and" and "or" do not return Boolean values True or False; they actually return the last
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Python - Using a list with functions from the random module
摘要：To select a random item from the list or shuffle the list, you can use the choice and shuffle functions from the random module of the standard library
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LibreOffice Writer - How to insert a check/tick mark and circled numbers
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