This question already has answers here:
What is the use of "assert" in Python?
(23 answers)
Closed 6 years ago.
I have gone through many source code of functional test cases written in python. Many of the code uses assert for testing equality, why so?
In most test runners, a test failure is indicated by raising an exception - which is what the assert() function does if its argument evaluates to False.
Thus assert(1 == 0) will fail, and abort that specific test with an AssertionError exception. This is caught by the test framework, and the test is marked as having failed.
The framework/test-runner then moves on to the next test.
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This question already has answers here:
Is it possible to escape a reserved word in Python?
(5 answers)
Closed 2 years ago.
Currently I am trying to implement an API in Python that originally was written in another programming language. This API has a function called except. I am trying to implement this function in Python but obviously this resulted in an error as except is already part of the Python language. It's probably bad practice, but does someone know if it's even possible to declare a function called except?
def except():
print('hi')
>>>
def except():
^
SyntaxError: invalid syntax
It's not possible; except is a Python keyword and cannot be used as a user-defined name in any way. You can find the complete list of keywords through the keyword module.
No it is a reserved keywords. They can't be used to declare a variable or a function.
You can't declare a method named "except" cause "except" is a reserved keyword in python but you can use "Except"
This question already has answers here:
Why does code like `str = str(...)` cause a TypeError, but only the second time?
(20 answers)
Closed 6 years ago.
I have used print to store value like:
print=3
After then I am not able to use it to print any message:
print('a message')
Its giving error:
'int object is not callable'
Is there any way to use print both as a variable and a functions? If not then Why not python just makes built-in function names as keyword to remove this conflict?
Functions and data share the same namespace in Python -- as they do in many other languages (the entire family of LISP-1s comes to mind first, including Scheme and Clojure; also Ruby, Groovy, and I'm sure many more).
Thus no, you cannot do this. Widely available checkers (pylint, pychecker, etc) will catch and report on attempts to shadow builtins (such as print) with data.
This question already has answers here:
How to use "pass" statement?
(18 answers)
Closed 6 years ago.
What does pass mean in python? I have seen it used and I do not see why you need to use it or what it does? I guess I could say it passes over whatever function it is in, but why include it?
Quoth the doc:
The pass statement does nothing. It can be used when a statement is required syntactically but the program requires no action.
References:
https://docs.python.org/2/reference/simple_stmts.html#the-pass-statement
https://docs.python.org/2/tutorial/controlflow.html#pass-statements
"It is used when a statement is required syntactically but you do not want any command or code to execute.
The pass statement is a null operation; nothing happens when it executes. The pass is also useful in places where your code will eventually go, but has not been written yet (e.g., in stubs for example):"
https://www.tutorialspoint.com/python/python_pass_statement.htm
This question already has answers here:
Using pass on a non necessary else statement
(5 answers)
Closed 8 years ago.
Is there a preferred/proper style?
This:
def fx(Boolean):
if Boolean:
# Do stuff.
else:
pass
Or this:
def fx(Boolean):
if Boolean:
# Do stuff.
Is it preferred/proper to include else: pass if you don't want anything to happen?
I've read PEP 8 - Style Guide for Python Code and did not find anything concerning my question.
You should never include else: pass. It's superfluous. Just omit the else; it's intentionally an optional keyword.
If you don't need the else if there is no reason to add it. It will just confuse other people reading your code in the future (ie yourself a few months later).
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
design of python: why is assert a statement and not a function?
In Python 3, print was made into a function. What are the benefits of having assert be a statement?
For optimization. If you run your Python script with the -O option no code will be generated for assert statements. This would not be possible if assert were a function.
See the documentation on assert, which references this behavior.