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Creating a singleton in Python
...mple implementation:
class Singleton(type):
_instances = {}
def __call__(cls, *args, **kwargs):
if cls not in cls._instances:
cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
return cls._instances[cls]
class Logger(object):
__meta...
How to rollback a specific migration?
...nt to go back.
For example:
rake db:rollback STEP=5
Will also rollback all the migration that happened later (4, 3, 2 and also 1).
To roll back all migrations back to (and including) a target migration, use: (This corrected command was added AFTER all the comments pointing out the error in the ...
What exactly is Python multiprocessing Module's .join() Method Doing?
... threading or multiprocessing, is not related to str.join() - it's not actually concatenating anything together. Rather, it just means "wait for this [thread/process] to complete". The name join is used because the multiprocessing module's API is meant to look as similar to the threading module's AP...
Why are margin/padding percentages in CSS always calculated against width?
... The actual reasoning of why the spec is written this way is still, technically, unknown.
Element height is defined by the height of the
children. If an element has padding-top: 10% (relative to parent
height), that is going to affect the height of the parent. Since the
height of the child...
How to clear jQuery validation error messages?
...ry validation plugin for client side validation.
Function editUser() is called on click of 'Edit User' button, which displays error messages.
...
Why do we declare Loggers static final?
...ic final Logger log = LoggerFactory.getLogger(Foo.class);
The former way allows you to use the same logger name (name of the actual class) in all classes throughout the inheritance hierarchy. So if Bar extends Foo, both will log to Bar logger. Some find it more intuitive.
...
Why is JavaScript called JavaScript, since it has nothing to do with Java? [closed]
...
JavaScript, was originally named Mocha, later it was renamed to LiveScript, and then to JavaScript.
The LiveScript to JavaScript name change came because Netscape and Sun did a license agreement.
The language was then submitted for standarizatio...
TypeError: not all arguments converted during string formatting python
The program is supposed to take in two names, and if they are the same length it should check if they are the same word. If it's the same word it will print "The names are the same" . If they are the same length but with different letters it will print "The names are different but the same length...
Trim trailing spaces in Xcode
...
Starting from Xcode 4.4 whitespaces will be trimmed automatically by default, unless the line is all whitespace. You can also activate Including whitespace-only lines to fix this, which is not active by default.
Go to Xcode > Preferences > Text Editing > While editing
...
How to prevent a jQuery Ajax request from caching in Internet Explorer?
...
You can disable caching globally using $.ajaxSetup(), for example:
$.ajaxSetup({ cache: false });
This appends a timestamp to the querystring when making the request. To turn cache off for a particular $.ajax() call, set cache: false on it locally, ...