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What's a correct and good way to implement __hash__()?
What's a correct and good way to implement __hash__() ?
6 Answers
6
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Difference between abstract class and interface in Python
... NotImplementedError("Class %s doesn't implement aMethod()" % (self.__class__.__name__)) is more informative error message :)
– naught101
Sep 3 '14 at 1:43
9
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What does “hashable” mean in Python?
...if it has a hash value which never changes during its lifetime (it needs a __hash__() method), and can be compared to other objects (it needs an __eq__() or __cmp__() method). Hashable objects which compare equal must have the same hash value.
Hashability makes an object usable as a dictionary ...
Is it possible to print a variable's type in standard C++?
...at I'm recommending below is:
template <typename T> std::string type_name();
which would be used like this:
const int ci = 0;
std::cout << type_name<decltype(ci)>() << '\n';
and for me outputs:
int const
<disclaimer> I have not tested this on MSVC. </disclai...
List directory tree structure in python?
...
Here's a function to do that with formatting:
import os
def list_files(startpath):
for root, dirs, files in os.walk(startpath):
level = root.replace(startpath, '').count(os.sep)
indent = ' ' * 4 * (level)
print('{}{}/'.format(indent, os.path.basename(root)))
...
Define a lambda expression that raises an Exception
...
There is more than one way to skin a Python:
y = lambda: (_ for _ in ()).throw(Exception('foobar'))
Lambdas accept statements. Since raise ex is a statement, you could write a general purpose raiser:
def raise_(ex):
raise ex
y = lambda: raise_(Exception('foobar'))
But if...
Using logging in multiple modules
...ave a logger defined like this:
import logging
logger = logging.getLogger(__name__)
near the top of the module, and then in other code in the module do e.g.
logger.debug('My message with %s', 'variable data')
If you need to subdivide logging activity inside a module, use e.g.
loggerA = loggin...
relative path in require_once doesn't work
...
Use
__DIR__
to get the current path of the script and this should fix your problem.
So:
require_once(__DIR__.'/../class/user.php');
This will prevent cases where you can run a PHP script from a different folder and therefo...
How can I get the version defined in setup.py (setuptools) in my package?
...what your question appears to actually be asking), you can use:
import pkg_resources # part of setuptools
version = pkg_resources.require("MyProject")[0].version
Store version string for use during install
If you want to go the other way 'round (which appears to be what other answer authors her...
os.path.dirname(__file__) returns empty
...get the dirname of the absolute path, use
os.path.dirname(os.path.abspath(__file__))
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