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Define a lambda expression that raises an Exception
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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...
Python extending with - using super() Python 3 vs Python 2
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super() (without arguments) was introduced in Python 3 (along with __class__):
super() -> same as super(__class__, self)
so that would be the Python 2 equivalent for new-style classes:
super(CurrentClass, self)
for old-style classes you can always use:
class Classname(OldStyleParen...
Is there a Python caching library?
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From Python 3.2 you can use the decorator @lru_cache from the functools library.
It's a Last Recently Used cache, so there is no expiration time for the items in it, but as a fast hack it's very useful.
from functools import lru_cache
@lru_cache(maxsize=256)
def f(x):
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How to create REST URLs without verbs?
...ercase is best
Don't use implementation-specific extensions in your URIs (.php, .py, .pl, etc.)
Don't fall into RPC with your URIs
Do limit your URI space as much as possible
Do keep path segments short
Do prefer either /resource or /resource/; create 301 redirects from the one you don't use
Do use ...
what does the __file__ variable mean/do?
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When a module is loaded from a file in Python, __file__ is set to its path. You can then use that with other functions to find the directory that the file is located in.
Taking your examples one at a time:
A = os.path.join(os.path.dirname(__file__), '..')
# A is the par...
SQL SELECT WHERE field contains words
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This move was incredible ,, I am Really JEALOUS :( _______________________________________________________________________________________ INNER JOIN (@FilterTable F1 ON T.Column1 LIKE '%' + F1.Data + '%' LEFT JOIN (@FilterTable F2 ON T.Column1 NOT LIKE '%' + F2.Data + ...
How to create a custom string representation for a class object?
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Implement __str__() or __repr__() in the class's metaclass.
class MC(type):
def __repr__(self):
return 'Wahaha!'
class C(object):
__metaclass__ = MC
print C
Use __str__ if you mean a readable stringification, use __repr__ fo...
Understanding the difference between __getattr__ and __getattribute__
I am trying to understand the difference between __getattr__ and __getattribute__ , however, I am failing at it.
4 Answe...
Evaluating a mathematical expression in a string
...I've rewrapped fourFn into a numeric parser class for easier reuse.
from __future__ import division
from pyparsing import (Literal, CaselessLiteral, Word, Combine, Group, Optional,
ZeroOrMore, Forward, nums, alphas, oneOf)
import math
import operator
__author__ = 'Paul McGu...
What GRANT USAGE ON SCHEMA exactly do?
...read-only permissions to the db role that must access the database from my php scripts, and I have a curiosity: if I execute
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