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Ruby Standard Library has a Singleton module which implements the Singleton pattern. The first step in creating a Singleton class is to require and include the Singleton module in a class: require 'singleton' class Logger include Singleton end If you try to instantiate this class as you n...

The delete operator deletes a property from an object. Syntax: delete object.property delete object['property'] Returns: If deletion is successful, or the property did not exist: true If the property to be deleted is an own non-configurable property (can't be deleted): false in non...

The typeof operator returns the data type of the unevaluated operand as a string. Syntax: typeof operand Returns: These are the possible return values from typeof: TypeReturn valueUndefined"undefined"Null"object"Boolean"boolean"Number"number"String&quot...

DynamoDB is a fully managed service provided by AWS. It does not need to be installed or configured. AWS is responsible for all administrative burdens of operating, scalling and backup/restore of the distributed database.

When Oracle implicitly converts from a DATE to a string or vice-versa (or when TO_CHAR() or TO_DATE() are explicitly called without a format model) the NLS_DATE_FORMAT session parameter will be used as the format model in the conversion. If the literal does not match the format model then an excepti...

When it comes to geographic data, R shows to be a powerful tool for data handling, analysis and visualisation. Often, spatial data is avaliable as an XY coordinate data set in tabular form. This example will show how to create a spatial data set from an XY data set. The packages rgdal and sp provi...

To destroy, delete, or unset an array: unset array To destroy, delete, or unset a single array element: unset array[10]

Windows There are two options how to install Kivy: First ensure python tools are up-to-date. python -m pip install --upgrade pip wheel setuptools Then install the basic dependencies. python -m pip install docutils pygments pypiwin32 kivy.deps.sdl2 kivy.deps.glew Although Kivy already has p...

You can install three.js via npm: npm install three You can add it from a CDN to your HTML: <script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r83/three.js"></script> You can use the three.js editor to give it a try and download the project as an ex...

Arithmetic if statement allows one to use three branches depending on the result of an arithmetic expression if (arith_expr) label1, label2, label3 This if statement transfers control flow to one of the labels in a code. If the result of arith_expr is negative label1 is involved, if the result i...

Detailed instructions on getting tfs set up or installed.

Unlike Big-O notation, which represents only upper bound of the running time for some algorithm, Big-Theta is a tight bound; both upper and lower bound. Tight bound is more precise, but also more difficult to compute. The Big-Theta notation is symmetric: f(x) = Ө(g(x)) <=> g(x) = Ө(f(x)) An ...

First: The path structure If you don't have it you need to create the middleware folder within your app following the structure: yourproject/yourapp/middleware The folder middleware should be placed in the same folder as settings.py, urls, templates... Important: Don't forget to create the ini...

When you extend a class, you can override methods that the inherited class defines using the override keyword: public class Example { public function test():void { trace('It works!'); } } public class AnotherExample extends Example { public override function test():void ...

Number of unique elements in a series: In [1]: id_numbers = pd.Series([111, 112, 112, 114, 115, 118, 114, 118, 112]) In [2]: id_numbers.nunique() Out[2]: 5 Get unique elements in a series: In [3]: id_numbers.unique() Out[3]: array([111, 112, 114, 115, 118], dtype=int64) In [4]: df = pd.Da...

Detailed instructions on getting tomcat set up or installed.

SAS can be run in client-server model, using either the Enterprise Guide thick client or the SAS Studio thin (web-enabled) client, or in "local server" mode where a fully functional SAS system is present on a local machine (Windows or Unix/Linux desktop or server running in interactive mod...

You need to set who you are *before* creating any commit. That will allow commits to have the right author name and email associated to them. It has nothing to do with authentication when pushing to a remote repository (e.g. when pushing to a remote repository using your GitHub, BitBucket, or Gi...

Who says you cannot throw multiple exceptions in one method. If you are not used to playing around with AggregateExceptions you may be tempted to create your own data-structure to represent many things going wrong. There are of course were another data-structure that is not an exception would be mor...

You can get list of available commands by following way: >>> python manage.py help If you don't understand any command or looking for optional arguments then you can use -h argument like this >>> python manage.py command_name -h Here command_name will be your desire command...