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Difference between __getattr__ vs __getattribute__
... the attribute wasn't found the usual ways. It's good for implementing a fallback for missing attributes, and is probably the one of two you want.
__getattribute__ is invoked before looking at the actual attributes on the object, and so can be tricky to implement correctly. You can end up in infi...
What is the dependency inversion principle and why is it important?
...
Check this document out: The Dependency Inversion Principle.
It basically says:
High level modules should not depend upon low-level modules. Both should depend upon abstractions.
Abstractions should never depend upon details. Details should depend upon abstractions.
As to why it is importa...
Reload django object from database
...
Not sure what "All non-deferred fields are updated "mentioned in the docs means?
– Yunti
Nov 13 '15 at 18:15
1
...
What's the best way to parse command line arguments? [closed]
... will accept -q or --query as options, store the argument in an attribute called query and has a default value if you don't specify it. It is also self-documenting in that you declare the help argument (which will be used when run with -h/--help) right there with the option.
Usually you parse your...
How to convert list of tuples to multiple lists?
...
xs, ys = [x for x, y in zs], [y for x, y in zs]
return xs, ys
if __name__ == '__main__':
from timeit import timeit
setup_string='''\
N = 2000000
xs = list(range(1, N))
ys = list(range(N+1, N*2))
zs = list(zip(xs, ys))
from __main__ import t1, t2, t3
'''
print(f'zip:\t\t{timeit(...
What's the scope of a variable initialized in an if statement?
...ked only at runtime -- that is, when you get to the print x statement. If __name__ didn't equal "__main__" then you would get an exception: NameError: name 'x' is not defined.
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improve this ...
Linq to Sql: Multiple left outer joins
...
This may be cleaner (you dont need all the into statements):
var query =
from order in dc.Orders
from vendor
in dc.Vendors
.Where(v => v.Id == order.VendorId)
.DefaultIfEmpty()
from status
in dc.Status
.Where(...
“Variable” variables in Javascript?
...usly consider that). It is possible to access some global variables dynamically via window, but that doesn't work for variables local to a function. Global variables that do not become a property of window are variables defined with let and const, and classes.
There is almost always a better soluti...
Python decorators in classes
...
Would something like this do what you need?
class Test(object):
def _decorator(foo):
def magic( self ) :
print "start magic"
foo( self )
print "end magic"
return magic
@_decorator
def bar( self ) :
print "normal call"
test ...
Select first row in each GROUP BY group?
...
On Oracle 9.2+ (not 8i+ as originally stated), SQL Server 2005+, PostgreSQL 8.4+, DB2, Firebird 3.0+, Teradata, Sybase, Vertica:
WITH summary AS (
SELECT p.id,
p.customer,
p.total,
ROW_NUMBER() OVER(PARTITION BY p.cus...