Tutorial by Examples: p

After following the instructions above and installing Leiningen, start a new project by running: lein new <project-name> This will setup a Clojure project with the default Leiningen template within the <project-name> folder. There are several templates for Leiningen, which affect the...

Introduction In this minimalist example, using pytest we're going to test that indeed our Hello World app does return "Hello, World!" with an HTTP OK status code of 200, when hit with a GET request on the URL / First let's install pytest into our virtualenv pip install pytest And jus...

os.access is much better solution to check whether directory exists and it's accesable for reading and writing. import os path = "/home/myFiles/directory1" ## Check if path exists os.access(path, os.F_OK) ## Check if path is Readable os.access(path, os.R_OK) ## Check if path i...

Multiple transforms can be applied to an element in one property like this: transform: rotate(15deg) translateX(200px); This will rotate the element 15 degrees clockwise and then translate it 200px to the right. In chained transforms, the coordinate system moves with the element. This means tha...

h2 { /* adds a 1px space horizontally between each letter; also known as tracking */ letter-spacing: 1px; } The letter-spacing property is used to specify the space between the characters in a text. ! letter-spacing also supports negative values: p { letter-spacing: -1px; }...

This error appears while trying to update or delete records without including the WHERE clause that uses the KEY column. To execute the delete or update anyway - type: SET SQL_SAFE_UPDATES = 0; To enable the safe mode again - type: SET SQL_SAFE_UPDATES = 1;

The Premain class will contain the method "premain(String agentArgs Instrumentation inst)" Here is an example: import java.lang.instrument.Instrumentation; public class PremainExample { public static void premain(String agentArgs, Instrumentation inst) { System.out.print...

A very useful feature of Swift 2.2 is having the ability of extending protocols. It works pretty much like abstract classes when regarding a functionality you want to be available in all the classes that implements some protocol (without having to inherit from a base common class). protocol FooPro...

Props are used to transfer data from parent to child component. Props are read only. Child component can only get the props passed from parent using this.props.keyName. Using props one can make his component reusable.

Once setup is completed. Copy the code below to index.android.js or to index.ios.js file to use the props. import React, { Component } from 'react'; import { AppRegistry, Text, View } from 'react-native'; class Greeting extends Component { render() { return ( <Text>Hello {t...

Generally speaking, empty commits (or commits with state that is identical to the parent) is an error. However, when testing build hooks, CI systems, and other systems that trigger off a commit, it's handy to be able to easily create commits without having to edit/touch a dummy file. The --allow-e...

It's a very common extension that allows type classes with multiple type parameters. You can think of MPTC as a relation between types. {-# LANGUAGE MultiParamTypeClasses #-} class Convertable a b where convert :: a -> b instance Convertable Int Float where convert i = fromIntegr...

A syntactic extension that allows applying the tuple constructor (which is an operator) in a section way: (a,b) == (,) a b -- With TupleSections (a,b) == (,) a b == (a,) b == (,b) a N-tuples It also works for tuples with arity greater than two (,2,) 1 3 == (1,2,3) Mapping This can be u...

The following expressions are sequenced: a && b a || b a , b a ? b : c for ( a ; b ; c ) { ... } In all cases, the expression a is fully evaluated and all side effects are applied before either b or c are evaluated. In the fourth case, only one of b or c will be evaluated. In the l...

C11 The following expressions are unsequenced: a + b; a - b; a * b; a / b; a % b; a & b; a | b; In the above examples, the expression a may be evaluated before or after the expression b, b may be evaluated before a, or they may even be intermixed if they correspond to several instruct...

Database transactions ensure that a set of data changes will only be made permanent if every statement is successful. Any query or code failure during a transaction can be caught and you then have the option to roll back the attempted changes. PDO provides simple methods for beginning, committing,...

map is a function in functional programming which given a list and a function, returns a new list with the function applied to each item in that list. In Elixir, the map/2 function is in the Enum module. iex> Enum.map([1, 2, 3, 4], fn(x) -> x + 1 end) [2, 3, 4, 5] Using the alternative c...

The following will create dist/output.jar from the source code in src and the libraries in lib, and will use src/Main.java as the main class. <project name="Project" default="main" basedir="."> <property name="src.dir" value="src&quot...

If you want to develop and contribute to the Flask project, clone the repository and install the code in development mode. git clone ssh://github.com/pallets/flask cd flask python3 -m venv env source env/bin/activate pip install -e . There are some extra dependencies and tools to be aware ...

Ajax Get: Solution 1: $.get('url.html', function(data){ $('#update-box').html(data); }); Solution 2: $.ajax({ type: 'GET', url: 'url.php', }).done(function(data){ $('#update-box').html(data); }).fail(function(jqXHR, textStatus){ alert('Error occured: ' + te...