Tutorial by Examples: ha

NCHAR and NVARCHAR

UNICODE string data types of either fixed length or variable length. Syntax: NCHAR [ ( n_chars ) ] NVARCHAR [ ( n_chars | MAX ) ] Use MAX for very long strings that may exceed 8000 characters.

SQL • Data Types

In Python 3, many of the dictionary methods are quite different in behaviour from Python 2, and many were removed as well: has_key, iter* and view* are gone. Instead of d.has_key(key), which had been long deprecated, one must now use key in d. In Python 2, dictionary methods keys, values and items ...

Python Language • Incompatibilities moving from Python 2 to Python 3

What is SFINAE

SFINAE stands for Substitution Failure Is Not An Error. Ill-formed code that results from substituting types (or values) to instantiate a function template or a class template is not a hard compile error, it is only treated as a deduction failure. Deduction failures on instantiating function templa...

C++ • SFINAE (Substitution Failure Is Not An Error)

Work with Arrays, Not With Ranges

Office Blog - Excel VBA Performance Coding Best Practices Often, best performance is achieved by avoiding the use of Range as much as possible. In this example we read in an entire Range object into an array, square each number in the array, and then return the array back to the Range. This accesse...

excel-vba • VBA Best Practices

Simple Bar Chart

index.html <!doctype html> <html> <head> <title>D3 Sample</title> </head> <body>  <div id=...

d3.js • Getting started with d3.js

hasattr function bug in Python 2

In Python 2, when a property raise a error, hasattr will ignore this property, returning False. class A(object): @property def get(self): raise IOError class B(object): @property def get(self): return 'get in b' a = A() b = B() print 'a hasattr get:...

Python Language • Incompatibilities moving from Python 2 to Python 3

Changing routes (using templates & directives)

Now that the routes are set up, we need some way to actually change routes. This example will show how to change routes using the template, but it is possible to change routes in TypeScript. Here is one example (without binding): <a routerLink="/home">Home</a> If the user...

Angular 2 • Routing (3.0.0+)

Push a specific object to a remote branch

General syntax git push <remotename> <object>:<remotebranchname> Example git push origin master:wip-yourname Will push your master branch to the wip-yourname branch of origin (most of the time, the repository you cloned from). Delete remote branch Deleting the remote br...

Git • Pushing

Character Guide

Note that some syntax elements have different behavior depending on the expression. SyntaxDescription?Match the preceding character or subexpression 0 or 1 times. Also used for non-capturing groups, and named capturing groups.*Match the preceding character or subexpression 0 or more times.+Match th...

Regular Expressions • Getting started with Regular Expressions

Encoding/decoding error handling

.encode and .decode both have error modes. The default is 'strict', which raises exceptions on error. Other modes are more forgiving. Encoding >>> "£13.55".encode('ascii', errors='replace') b'?13.55' >>> "£13.55".encode('ascii', errors='ignore') b'13.55' ...

Python Language • Unicode and bytes

Change list

Let's say you have a simple myblog app with the following model: from django.conf import settings from django.utils import timezone class Article(models.Model): title = models.CharField(max_length=70) slug = models.SlugField(max_length=70, unique=True) author = models.ForeignKe...

Django • Administration

Writing a lens without Template Haskell

To demystify Template Haskell, suppose you have data Example a = Example { _foo :: Int, _bar :: a } then makeLenses 'Example produces (more or less) foo :: Lens' (Example a) Int bar :: Lens (Example a) (Example b) a b There's nothing particularly magical going on, though. You can write ...

Haskell Language • Lens

Optional Chaining

You can use Optional Chaining in order to call a method, access a property or subscript an optional. This is done by placing a ? between the given optional variable and the given member (method, property or subscript). struct Foo { func doSomething() { print("Hello World!") ...

Swift Language • Optionals

Ghost element technique (Michał Czernow's hack)

This technique works even when the container's dimensions are unknown. Set up a "ghost" element inside the container to be centered that is 100% height, then use vertical-align: middle on both that and the element to be centered. CSS /* This parent can be any width and height */ .block...

CSS • Centering

Including internal css file with another css file as a dependency

function themeSlug_enqueue_scripts() { wp_enqueue_style( 'themeSlug-reset', get_template_directory_uri() .'/css/reset.css', '1.0.0' ); wp_enqueue_style( 'themeSlug-style', get_template_directory_uri() .'/style.css', 'themeSlug-reset', '1.0.0'); } add_action('wp_enqueue_scripts', 'themeSl...

WordPress • Enqueuing Styles

Padding Shorthand

The padding property sets the padding space on all sides of an element. The padding area is the space between the content of the element and its border. Negative values are not allowed. To save adding padding to each side individually (using padding-top, padding-left etc) can you write it as a shor...

CSS • Padding

Character Encoding

The charset attribute specifies the character encoding for the HTML document and needs to be a valid character encoding (examples include windows-1252, ISO-8859-2, Shift_JIS, and UTF-8). UTF-8 (Unicode) is the most widely used and should be used for any new project. 5 <meta charset="UTF-8...

HTML • Meta Information

Show changes between two commits

git diff 1234abc..6789def # old new E.g.: Show the changes made in the last 3 commits: git diff @~3..@ # HEAD -3 HEAD Note: the two dots (..) is optional, but adds clarity. This will show the textual difference between the commits, regardless of where they are in the tree.

Git • Git Diff

Modifying classes with agents

Firstly, make sure that the agent being used has the following attributes in the Manifest.mf: Can-Redefine-Classes: true Can-Retransform-Classes: true Starting a java agent will let the agent access the class Instrumentation. With Instrumentation you can call addTransformer(ClassFileTransformer...

Java Language • Java Agents

Create a HashSet macro

// This example creates a macro `set!` that functions similarly to the built-in // macro vec! use std::collections::HashSet; macro_rules! set { ( $( $x:expr ),* ) => { // Match zero or more comma delimited items { let mut temp_set = HashSet::new(); // Create a ...

Rust • Macros