I am looking to understand some basic python functions in their entirety. How does the "del" produce this (in bash):
>>> temp = 1
>>> python = 1 + temp
>>>
>>>
>>> temp
1
>>>
>>> python
2
>>>
>>>
>>> del temp
>>>
>>>
>>> python
2
>>>
>>> temp
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'temp' is not defined
>>>
>>>
>>>
For del in python, it means
Deletion of a name removes the binding of that name from the local or global namespace
so when you del var, it removes this variable, and it's not usable when you call it again, that's why exception happens.
The way variables are created are in reference one time to another variable. In your example, python = temp + 1, python is equal to temp plus 1 at its time of definition.. The variable python does not re-compute every time the processor goes through a loop. Its value is only defined once. If a variable included in its definition changes, it does not change.
python delete variable within variable
temp is not inside python. In the line
python = 1 + temp
only the value of temp will be used to create the variable python. So if you delete temp, it won't affect python.
Here is the what the manual for the python del command says:
Deletion of a name removes the binding of that name from the local or global namespace, depending on whether the name occurs in a global statement in the same code block. If the name is unbound, a NameError exception will be raised.
pythonwas already assigned the value2. It doesn't make a reference totempin order to produce the result. What's unexpected here?