Python 3.9 is expected to be released on Monday 5th October 2020.
At the time of writing this article, the first candidate was recently released on 11 August.
Now, were anxiously waiting for the second release candidate which will probably be available from 14 September.
So, you might be wondering whats new in Python 3.9.
There are some significant changes that will dictate the way Python programs work.
Similarly, merge|and update|=Union Operators are added to thedict.
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So, lets take a closer look at all the upcoming features and improvements of Python 3.9.
Basically in LL(1), the Python developers had used several hacks to avoid its limitations.
In turn, it affects the flexibility of adding new language features.
The major difference between PEG and a context-free-grammar based parsers (e.g.
LL(1)) is that in PEG the choice operator is ordered.
On the other hand, PEG will venture to check whether the first alternative (e.g.
A) succeeds or not.
It will continue to the next alternative only whenAdoesnt succeed.
In simple words, PEG will check the alternatives in the order in which they are written.
Basically, its main purpose was to provide support for UTC.
In true sense, the local time zone is still not available.
In Python 3.9, theyre going to add support for the IANA time zone database.
Most of the time, this database is also referred to as tz or the Olson database.
So, dont get confused with these terms.
All of the IANA time zone functionality is packed inside thezoneinfomodule.
This database is very popular and widely distributed in Unix-like operating systems.
But, remember that Windows uses a completely different method for handling the time zones.
Thats why the developers are now introducing Union Operators like|for merging and|=for updating the dicts.
For example, earlier when we used1.update(d2)then it also modifiesd1.
Here we are creating a new temporary variable to hold the value.
But, this solution is not very efficient.
Thats the main reason behind adding those new Union Operators.
But, this is where the confusion starts.
Actually, these functions work with a set of characters instead of a substring.
But, in most cases, they make mistakes while handling empty strings.
So, a built-in solution can be very helpful for real-world apps.
pop in hinting generics in standard collections
Did you ever notice the duplicate collection hierarchy in thetypingmodule?
For example, you’re free to either usetyping.Listor the built-inlist.
The syntax can now be used in all standard collections that are available in this module.
The major plus of this feature is now users can easily annotate their code.
It even helps the instructors to teach Python in a better way.
Meaning it follows a linear order to tell which task will run before the other.
Thegraphlibmodule enables us to perform a topological sort or order of a graph.
Its mostly used with hashable nodes.
This can have unintended consequences because theres no guarantee whether the hash value is deterministic or not.
Also, from now onwards you must specify themodeargument to open aGzipFilefilefor writing.
Whats been removed?
You may have a look at the complete list onPythons website.
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