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This article mainly explains "what are the new functions of Python 3.8". The explanation in this article is simple and clear, easy to learn and understand. Please follow the ideas of Xiaobian and go deep into it slowly to study and learn "what are the new functions of Python 3.8" together!

1. New Module: Reading Metadata Calendar

The metadata of third-party packages can be read using the new importlib.metadata module. Version numbers can be obtained in script packages.

2. Dictionary inversion: sort

Dictionaries can now be iterated in reverse insertion sort with resented ( ).

3. Continue - finally

Because of Python implementation issues, it was previously illegal to add a continue statement to the Finally clause. That problem no longer exists.

for i inrange(2): try: print(i) finally: print('A sentence. ') continue print('This never shows. ') # Python >SyntaxError: 'continue'not supported inside 'finally' clause # Python 3.8 >>0 A sentence. 1 A sentence.

4. Indicates parameter type: makes code more powerful

Python functions accept only two arguments.

Position Parameters: Pass parameters according to the position of the parameters defined by the function.

Keyword Parameters: Use keywords to specify parameters.

In the following example, the values of parameters a and b can be determined by position parameters or keyword parameters, which is very flexible.

def my_func(a, b=1): return a+bmy_func(5,2) # both positional arguments my_func(a=5,b=2) # both keyword arguments

The new version of Python, distinguished by the syntax/and *, provides a way to specify acceptance of positional or keyword arguments. Note: Syntax * does not appear in Python 3.8.

In the example below, the first two parameters a and b accept only positional parameters, the middle parameters c and d accept positional or keyword parameters, and the last parameters e and f accept only keyword parameters.

defmy_func(a, b, /, c, d, *, e, f): return a+b+c+d+e+f my_func(1,2,3,4,5,6) # invalid as e and f are keyword-only my_func(a=1,b=2,3,4,e=5,f=6) # invalid as a and b are position-only my_func(1,2,c=3,4,e=5,f=6) # returns 21 my_unc(1,2,c=3,d=4,e=5,f=6) # returns 21

Why sacrifice flexibility? If parameter names are arbitrary and useless, keyword parameters should be excluded. If you expect parameter names in a function to change, specifying parameter types can prevent code from crashing and make your code more powerful.

5. Assignment Expressions: Improve Code Readability

Assignment expressions, also known as walrus operators, are new operators with the syntax:= that assign parts of larger expressions to variables. This is undoubtedly the most talked about new feature in Python 3.8.

Let's look at an example: the assignment expression b := a**2 assigns the square of a, which is 36, to b, and checks whether b is greater than 0.

a =6 # The following statement # assigns the value a ** 2 to variable b, # and then check if b > 0 is true if (b := a **2) >0: print(f'The square of {a} is {b}. ') # The square of 6 is 36.

Sometimes assignment expressions can make code simpler and more readable. Be careful not to abuse assignment expressions, however, because in some cases it can make code harder to understand.

# DON'T DO THIS! a = 5 d = [b := a+1, a := b-1, a := a*2]

Assignment expressions are also available in other (older) programming languages, and programmers who wish to switch to Python will be able to use this new feature. Get a grip on assignment expressions before they flood the place.

6. F String 2.0: Tools for debugging

Python f string changed the rules of the game. F string is a syntax for formatting strings, concise and readable. By using the syntax f'{expr}' and enclosing the expression in curly braces, you can insert an expression into a string.

After Python updates, the equal sign "=" can be used as a format qualifier in the f string f'{expr=}' syntax. The output string is variable name = variable value, as follows:

# DON'T DO THIS! a = 5 d = [b := a+1, a := b-1, a := a*2]

For documentation or debugging purposes, it is often necessary to specify variable values. The F string makes debugging easy.

Of course, before you can dive into Python 3.8 programming, you need to master Python basics (essential).

These are Python's 6 new features that every Python novice can benefit from.

Thank you for reading, the above is "Python 3.8 new features what" content, after the study of this article, I believe that we have a deeper understanding of Python 3.8 new features what this problem, the specific use of the situation also needs to be verified by practice. Here is, Xiaobian will push more articles related to knowledge points for everyone, welcome to pay attention!

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