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Proper use of beginBackgroundTaskWithExpirationHandler
...ed.
Mine tend look something like this:
- (void) doUpdate
{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
[self beginBackgroundUpdateTask];
NSURLResponse * response = nil;
NSError * error = nil;
NSData * responseData = [NSU...
Accessing nested JavaScript objects and arays by string path
...
great stuff; using the lodash library, one can also do: _.get(object, nestedPropertyString);
– ian
Aug 13 '15 at 12:49
17
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Getting a list of all subdirectories in the current directory
...
Do not use os.walk('.').next()[1] or os.walk('.').__next__()[1] directly. Instead, use the built-in function next(), which is available both in Python 2 (see doc) and Python 3 (see doc). For example: next(os.walk('.'))[1].
– Lucio Paiva
...
Is it possible to make abstract classes in Python?
...
# Python 2
from abc import ABCMeta, abstractmethod
class Abstract:
__metaclass__ = ABCMeta
@abstractmethod
def foo(self):
pass
Whichever way you use, you won't be able to instantiate an abstract class that has abstract methods, but will be able to instantiate a subclass th...
How do I move to end of line in Vim?
...mode (Append). To jump the last non-blank character, you can press g then _ keys.
The opposite of A is I (Insert mode at beginning of line), as an aside. Pressing just the ^ will place your cursor at the first non-white-space character of the line.
...
Entity Framework rollback and remove bad migration
...g migrations that have been applied to the target database.
201508242303096_Bad_Migration
201508211842590_The_Migration_applied_before_it
201508211440252_And_another
This list shows the most recent applied migrations first. Pick the migration that occurs in the list after the one you want to downgr...
Python ElementTree module: How to ignore the namespace of XML files to locate matching element when
...s ET
# instead of ET.fromstring(xml)
it = ET.iterparse(StringIO(xml))
for _, el in it:
prefix, has_namespace, postfix = el.tag.partition('}')
if has_namespace:
el.tag = postfix # strip all namespaces
root = it.root
This is based on the discussion here:
http://bugs.python.org/issu...
How to calculate moving average using NumPy?
... an off-by-one wrong indexing spotted by Bean in the code. EDIT
def moving_average(a, n=3) :
ret = np.cumsum(a, dtype=float)
ret[n:] = ret[n:] - ret[:-n]
return ret[n - 1:] / n
>>> a = np.arange(20)
>>> moving_average(a)
array([ 1., 2., 3., 4., 5., 6., 7....
Calculate difference in keys contained in two Python dictionaries
...nged values
(4) keys same in both and unchanged values
"""
def __init__(self, current_dict, past_dict):
self.current_dict, self.past_dict = current_dict, past_dict
self.set_current, self.set_past = set(current_dict.keys()), set(past_dict.keys())
self.intersect = s...
String concatenation: concat() vs “+” operator
...ial #3; //Method java/lang/StringBuilder."<init>":()V
7: aload_1
8: invokevirtual #4; //Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
11: aload_2
12: invokevirtual #4; //Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljav...