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As far as I know, now we can declare variables using type annotation syntax in Python 3.6 as following code.
def printInt():
a: int = 0
b: int = 1
c: int = 2
print(a, b, c)
What I want to do is declaring variables a, b, c in one line.
I tried a, b, c: int, but it returns error.
Also a: int=0, b: int=1, c: int=2 returns error too.
Is there any way to declare multiple variables using type annotation syntax in one line?
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Python assigns values from right to left. When assigning multiple variables in a single line, different variable names are provided to the left of the assignment operator separated by a comma. The same goes for their respective values except they should to the right of the assignment operator.
Python lists are annotated based on the types of the elements they have or expect to have. Starting with Python ≥3.9, to annotate a list, you use the list type, followed by [] . [] contains the element's type data type.
Variable Annotation is basically an enhancement of type hinting, which was introduced in Python 3.5. The full explanation behind Variable Annotation is explained in PEP 526. In this article, we give have a quick refresher on type hinting and then introduce the new Variable Annotation syntax.
Yes you can and it is slightly more nuanced than it seems. You can use the same syntax in function parameter declarations: func foo(a, b string) { // takes two string parameters a and b ... } Then comes the short-hand syntax for declaring and assigning a variable at the same time.
Variable Annotation is basically an enhancement of type hinting, which was introduced in Python 3.5. The full explanation behind Variable Annotation is explained in PEP 526. In this article, we give have a quick refresher on type hinting and then introduce the new Variable Annotation syntax.
Since the initial introduction of type hints in PEP 484 and PEP 483, a number of PEPs have modified and enhanced Python’s framework for type annotations. These include: Introducing syntax for annotating variables outside of function definitions, and ClassVar
Just to reiterate, in Python 3.5 you could do variable annotation, but you had to put that annotation in a comment: Note that if you change the code to use the Python 3.5 variation of variable annotation syntax, mypy will still flag the error correctly. You have to specify the "type:" after the pound sign though.
You don’t need to annotate everything. The typing module adds support for type hints. It contains some of the types you will use most often: List, Dict, and Tuple. Similarly, you can annotate that a dictionary maps strings to integers by Dict [str, int] . So List, Dict, and Tuple are generics.
If you really want to use annotation then you can do this in this form:-
a: int;b: int;c: int
a,b,c = range(3)
print(a,b,c) #As output 0 1 2
a: int = 0; b: int = 1; c: int = 2
would actually work.
If you are looking for a way to avoid repeating int all times, I am afraid you cannot as of Python 3.7.
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