✋ Update: This post was originally published on my blog decodingweb.dev, where you can read the latest version for a 💯 user experience. ~reza
Python raises “SyntaxError: cannot assign to function call here. Maybe you meant ‘==’ instead of ‘=’?” when a function call is the left-hand side operand in a value assignment:
# Raises 🚫 SyntaxError
f() = 23
Python also provides you a hint, assuming you meant to use the equality operator (==
):
File /dwd/sandbox/test.py, line 4
my_func() = 12
^^^^^^^^
SyntaxError: cannot assign to function call here. Maybe you meant '==' instead of '='?
Most of the time, the reason is a typo in your code - usually a missing =
.
How to fix "SyntaxError: cannot assign to function call"
The long error "SyntaxError: cannot assign to function call here. Maybe you meant '==' instead of '='?" occurs under various scenarios:
- Using the assignment operator (
=
) instead of the equality operator (==
) - Wrong left-hand side operand
- Incomplete list comprehension
Let's see some examples.
Using the assignment operator (=
) instead of the equality operator (==
): One of the most common causes of this SyntaxError is using the assignment operator (=
) instead of the equality operator (==
) in value comparisons:
def my_func():
return 12
# 🚫 SyntaxError
if my_func() = 12:
print ('Passed')
In the above example, we're trying to compare the return value of my_func()
to the value of 12
. However, the =
operator isn't a comparison operator.
To fix the error, we use the equality operator (==
) instead:
def my_func():
return 12
if my_func() == 12:
print ('Passed')
# Output: Passed
Wrong left-hand side operand (in assignment statements): Assignment statements bind names to values. (e.g., age = 25
)
Based on Python syntax and semantics, the left-hand side of the assignment operator (=
) should always be an identifier - an arbitrary name you choose for a specific value (a.k.a variable). For instance, age
for 25
.
That said, if you have a function call as the left-hand side operand, you'll get the "SyntaxError: cannot assign to function call here. Maybe you meant '==' instead of '='?" error.
def get_age():
return 25
# 🚫 SyntaxError
get_age() = age
If your code looks like the above, switch sides:
def get_age():
return 25
age = get_age()
Incomplete list comprehension: A confusing scenario that leads to this SyntaxError is a wrong list comprehension statement.
We usually use list comprehensions to generate a list where each element is the result of an operation applied to each member of another sequence or iterable.
Imagine you have a range object from 1
to 10
, and you want to calculate the square root of each element and store them in a separate list.
A list comprehension statement consists of brackets containing an expression (e.g., x**2
) followed by a for clause (e.g., for x in range(1, 10)
).
We can implement the above example like so:
squares = [x**2 for x in range(1, 10)]
print(squares)
# Output: [1, 4, 9, 16, 25, 36, 49, 64, 81]
In the above example, x**2
is applied to every item in our range. Now, if you accidentally replace the for keyword with in, you'll get this SyntaxError:
# 🚫 SyntaxError
squares = [x**2 in x for range(1, 10)]
print(squares)
The reason is whatever follows for is supposed to be the variable that holds the current item on each iteration.
Alright, I think it does it. I hope this quick guide helped you solve your problem.
Thanks for reading.
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