Some New Features in Python 3.9

In this Python article we want to learn about Some New Features in Python 3.9, as you

know Python 3.9 was released in 5th October 2020, and there has been some new

improvements on python language, from two new method of merge and update on dictionary

class, introduction of new string methods and zoneinfo library up to a number of new features

have been added. also a new stable and high-performing parser has been introduced in

python 3.9. in this lesson we want to introduce some New Features in Python 3.9 with

examples.

Dictionary Merge & Update Operators

Merge ( | ) and update ( |= ) operators have been added to the built-in dict class.

Those complement the existing dict.update and {**d1, **d2} methods of

merging dictionaries, now let’s create a simple example.

In here i have two dictionaries and i want to merge and update these two dictionaries,

now first let’s do this without Python 3.9 operators.

dict1 = {'name':'Parwiz', 'last_name':'Forogh'}

dict2 = {'email':'par@gmail.com'}

dict3 = {**dict1 , **dict2}
print(dict3)

dict1.update(dict2)
print(dict1)

dict1 = {'name':'Parwiz', 'last_name':'Forogh'}

dict2 = {'email':'par@gmail.com'}

dict3 = {**dict1 , **dict2}

print(dict3)

dict1.update(dict2)

print(dict1)

If you run the code, you can see that the dictionaries are merged and updated.

Now let’s do this using Python 3.9 new operators of Merge (|) and update (|=).

dict1 = {'name':'Parwiz', 'last_name':'Forogh'}

dict2 = {'email':'par@gmail.com'}


#merge operator
dict3 = dict1|dict2
print(dict3)

#update operator
dict1 |= dict2
print(dict1)

dict1 = {'name':'Parwiz', 'last_name':'Forogh'}

dict2 = {'email':'par@gmail.com'}

#merge operator

dict3 = dict1|dict2

print(dict3)

#update operator

dict1 |= dict2

print(dict1)

And if you run the code we will receive the same result.

String Methods for Removing Prefix and Suffix

Two new string methods for removing prefixes and suffixes have been added.

print("Geekscoders ".removeprefix("Gee"))
print("Geekscoders".removesuffix("ers"))

1 2	print("Geekscoders ".removeprefix("Gee")) print("Geekscoders".removesuffix("ers"))

Run the code and this is the result.

Type Hinting Generics in Standard Collections

In type annotations you can now use built-in collection types such as list and dict

as generic types instead of importing the corresponding capitalized types (e.g. List or Dict)

from typing.

Let’s first create an example before Python 3.9.

from typing import List

def greet_all(names: List[str]):
    for name in names:
        print("Hello", name)


greet_all(['GeeksCoders'])

from typing import List

def greet_all(names: List[str]):

for name in names:

print("Hello", name)

greet_all(['GeeksCoders'])

You can see in the above example we have imported List from typing, if we don’t do this

we will receive error in our code.

So now let’s create our same example with Python 3.9.

def greet_all(names: list[str]):
    for name in names:
        print("Hello", name)


greet_all(['Geekscoders'])

def greet_all(names: list[str]):

for name in names:

print("Hello", name)

greet_all(['Geekscoders'])

You can see that in Python 3.9 we don’t need to import the List from typing.

Run the code and this is the result.

ZoneInfo Module

The zoneinfo module brings support for the IANA time zone database to the standard

library. It adds zoneinfo.ZoneInfo, a concrete datetime.tzinfo implementation

backed by the system’s time zone data. if you are using Mac or Linux you can use the

zoneinfo directly, but if you are using window you to install a third party library that is

called tzdata.

pip install tzdata

1	pip install tzdata

And this is the code.

from zoneinfo import ZoneInfo
from datetime import datetime
dt = datetime(2020, 11, 18, 12, tzinfo=ZoneInfo("America/Los_Angeles"))
print(dt)
print(dt.tzinfo)
print(dt.tzname())