Tutorial by Examples: od

Definition: In computing, an event is an action or occurrence recognized by software that may be handled by the software. Computer events can be generated or triggered by the system, by the user or in other ways. Definition Source HTML events are "things" that happen to HTML ele...

Generator expressions are similar to list, dictionary and set comprehensions, but are enclosed with parentheses. The parentheses do not have to be present when they are used as the sole argument for a function call. expression = (x**2 for x in range(10)) This example generates the 10 first perfe...

You can include another Git repository as a folder within your project, tracked by Git: $ git submodule add https://github.com/jquery/jquery.git You should add and commit the new .gitmodules file; this tells Git what submodules should be cloned when git submodule update is run.

When you clone a repository that uses submodules, you'll need to initialize and update them. $ git clone --recursive https://github.com/username/repo.git This will clone the referenced submodules and place them in the appropriate folders (including submodules within submodules). This is equivale...

Add a key and value to a Dictionary var books = [Int: String]() //books = [:] books[5] = "Book 5" //books = [5: "Book 5"] books.updateValue("Book 6", forKey: 5) //[5: "Book 6"] updateValue returns the original value if one exists or nil. let previous...

Magic (also called dunder as an abbreviation for double-underscore) methods in Python serve a similar purpose to operator overloading in other languages. They allow a class to define its behavior when it is used as an operand in unary or binary operator expressions. They also serve as implementation...

This example uses the Cars Table from the Example Databases. UPDATE Cars SET TotalCost = TotalCost + 100 WHERE Id = 3 or Id = 4 Update operations can include current values in the updated row. In this simple example the TotalCost is incremented by 100 for two rows: The TotalCost of Car #3 i...

import operator reduce(operator.mul, [10, 5, -3]) # Out: -150

Publish and Subscribe for Node.JS Install PubNub NPM Package. npm install [email protected] Example Publish Subscribe with Node.JS var channel = "hello_world"; var pubnub = require("pubnub")({ publish_key : "your_pub_key" , subscribe_key : "your_sub_ke...

In addition to .done, .fail and .always promise callbacks, which are triggered based on whether the request was successful or not, there is the option to trigger a function when a specific HTTP Status Code is returned from the server. This can be done using the statusCode parameter. $.ajax({ t...

The math-module contains another math.pow() function. The difference to the builtin pow()-function or ** operator is that the result is always a float: import math math.pow(2, 2) # 4.0 math.pow(-2., 2) # 4.0 Which excludes computations with complex inputs: math.pow(2, 2+0j) TypeErro...

Supposing you have a class that stores purely integer values: class Integer(object): def __init__(self, value): self.value = int(value) # Cast to an integer def __repr__(self): return '{cls}({val})'.format(cls=self.__class__.__name__, ...

A submodule references a specific commit in another repository. To check out the exact state that is referenced for all submodules, run git submodule update --recursive Sometimes instead of using the state that is referenced you want to update to your local checkout to the latest state of that s...

You can have multiple versions of Xcode installed at the same time (including beta versions). Simply rename the application in Finder to avoid conflicts. Note: Installing Xcode from the App Store will tend to overwrite an existing version on your machine. You can also install Xcode from a direct ...

Abbreviated from https://blogs.dropbox.com/developers/2013/07/using-oauth-2-0-with-the-core-api/: Step 1: Begin authorization Send the user to this web page, with your values filled in: https://www.dropbox.com/oauth2/authorize?client_id=<app key>&response_type=code&redirect_uri=<...

A submodule is always checked out at a specific commit SHA1 (the "gitlink", special entry in the index of the parent repo) But one can request to update that submodule to the latest commit of a branch of the submodule remote repo. Rather than going in each submodule, doing a git checkout...

You can use the trap command to "trap" signals; this is the shell equivalent of the signal() or sigaction() call in C and most other programming languages to catch signals. One of the most common uses of trap is to clean up temporary files on both an expected and unexpected exit. Unfortu...

int i = 42; i = i++; /* Assignment changes variable, post-increment as well */ int a = i++ + i--; Code like this often leads to speculations about the "resulting value" of i. Rather than specifying an outcome, however, the C standards specify that evaluating such an expression produc...

Struct methods are very similar to functions: type User struct { name string } func (u User) Name() string { return u.name } func (u *User) SetName(newName string) { u.name = newName } The only difference is the addition of the method receiver. It may be declared either a...

An Xfermode (think "transfer" mode) works as a transfer step in drawing pipeline. When an Xfermode is applied to a Paint, the pixels drawn with the paint are combined with underlying pixels (already drawn) as per the mode: paint.setColor(Color.BLUE); paint.setXfermode(new PorterDuffXferm...