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What are metaclasses in Python?
... the 'class' statement) by calling the metaclass. Combined with the normal __init__ and __new__ methods, metaclasses therefore allow you to do 'extra things' when creating a class, like registering the new class with some registry or replace the class with something else entirely.
When the class st...
How to convert an xml string to a dictionary?
...ree import cElementTree as ElementTree
class XmlListConfig(list):
def __init__(self, aList):
for element in aList:
if element:
# treat like dict
if len(element) == 1 or element[0].tag != element[1].tag:
self.append(XmlDictC...
How to install Java SDK on CentOS?
...is, the lastest available version may be different.
java-1.7.0-openjdk.x86_64
The above package alone will only install JRE. To also install javac and JDK, the following command will do the trick:
$ yum install java-1.7.0-openjdk*
These packages will be installing (as well as their dependencie...
Python 2.7: Print to File
...If you want to use the print function in Python 2, you have to import from __future__:
from __future__ import print_function
But you can have the same effect without using the function, too:
print >>f1, 'This is a test'
...
C++ display stack trace on exception
...
On the home page of StackTrace, I see throw stack_runtime_error. Am I correct in deducing that this lib only works for exceptions derived from that class, and not for std::exception or exceptions from third-party libraries?
– Thomas
No...
Socket.IO - how do I get a list of connected sockets/clients?
...lients('room');
anymore. Instead you can use the following
var clients_in_the_room = io.sockets.adapter.rooms[roomId];
for (var clientId in clients_in_the_room ) {
console.log('client: %s', clientId); //Seeing is believing
var client_socket = io.sockets.connected[clientId];//Do whatever y...
Django rest framework nested self-referential objects
...('parentCategory', 'name', 'description', 'subcategories')
def get_related_field(self, model_field):
# Handles initializing the `subcategories` field
return CategorySerializer()
Actually, as you've noted the above isn't quite right.
This is a bit of a hack, but y...
Get Image size WITHOUT loading image into memory
... data (or call the load method).
Digging deeper, we see that .open calls _open which is a image-format specific overload. Each of the implementations to _open can be found in a new file, eg. .jpeg files are in JpegImagePlugin.py. Let's look at that one in depth.
Here things seem to get a bit tric...
Create singleton using GCD's dispatch_once in Objective-C
...er here: instancetype
+ (instancetype)sharedInstance
{
static dispatch_once_t once;
static id sharedInstance;
dispatch_once(&once, ^
{
sharedInstance = [self new];
});
return sharedInstance;
}
+ (Class*)sharedInstance
{
static dispatch_once_t once;
...
Regular expression to allow spaces between words
...
tl;dr
Just add a space in your character class.
^[a-zA-Z0-9_ ]*$
Now, if you want to be strict...
The above isn't exactly correct. Due to the fact that * means zero or more, it would match all of the following cases that one would not usually mean to match:
An empty string...