Tutorial by Examples: e

Blocks as Properties

@interface MyObject : MySuperclass @property (copy) void (^blockProperty)(NSString *string); @end When assigning, since self retains blockProperty, block should not contain a strong reference to self. Those mutual strong references are called a "retain cycle" and will prevent the...

Objective-C Language • Blocks

Most Common Real Life Key Value Coding Example

Key Value Coding is integrated into NSObject using NSKeyValueCoding protocol. What this means? It means that any id object is capable of calling valueForKey method and its various variants like valueForKeyPath etc. ' It also means that any id object can invoke setValue method and its various vari...

Objective-C Language • Key Value Coding / Key Value Observing

clone() method

The clone() method is used to create and return a copy of an object. This method arguable should be avoided as it is problematic and a copy constructor or some other approach for copying should be used in favour of clone(). For the method to be used all classes calling the method must implement the...

Java Language • Object Class Methods and Constructor

Reducing the Capacity of a Vector

A std::vector automatically increases its capacity upon insertion as needed, but it never reduces its capacity after element removal. // Initialize a vector with 100 elements std::vector<int> v(100); // The vector's capacity is always at least as large as its size auto const old_capacity...

C++ • std::vector

Installation or Setup

Google Apps Script does not require setup or installation. The only requirement is a Google Account. A Gmail account works as well as a Google Apps for Work/Education/Government account. You can create a new Google account by going to accounts.google.com Start your first script by going to script.g...

google-apps-script • Getting started with google-apps-script

Declaring a property

At its simplest, a property is a function which returns a Bool. prop_reverseDoesNotChangeLength xs = length (reverse xs) == length xs A property declares a high-level invariant of a program. The QuickCheck test runner will evaluate the function with 100 random inputs and check that the result is...

Haskell Language • QuickCheck

Dynamic class creation

Classes can be created dynamically through the use of Class.new. # create a new class dynamically MyClass = Class.new # instantiate an object of type MyClass my_class = MyClass.new In the above example, a new class is created and assigned to the constant MyClass. This class can be instanti...

Ruby Language • Classes

Using a template object

You can use an instance of an object to form your parameters public class SearchParameters { public string SearchString { get; set; } public int Page { get; set; } } var template= new SearchParameters { SearchString = "Dapper", Page = 1 }; var p = new DynamicParameters...

Dapper.NET • Dynamic Parameters

Joining Strings with a delimiter

Java SE 8 An array of strings can be joined using the static method String.join(): String[] elements = { "foo", "bar", "foobar" }; String singleString = String.join(" + ", elements); System.out.println(singleString); // Prints "foo + bar + foobar&qu...

Java Language • Strings

Current Date and Time

R is able to access the current date, time and time zone: Sys.Date() # Returns date as a Date object ## [1] "2016-07-21" Sys.time() # Returns date & time at current locale as a POSIXct object ## [1] "2016-07-21 10:04:39 CDT" as.numeric(Sys...

R Language • Date and Time

Formatting Dates

To format Dates we use the format(date, format="%Y-%m-%d") function with either the POSIXct (given from as.POSIXct()) or POSIXlt (given from as.POSIXlt()) d = as.Date("2016-07-21") # Current Date Time Stamp format(d,"%a") # Abbreviated Weekday ## [1] &qu...

R Language • The Date class

Formatting and printing date-time objects

# test date-time object options(digits.secs = 3) d = as.POSIXct("2016-08-30 14:18:30.58", tz = "UTC") format(d,"%S") # 00-61 Second as integer ## [1] "30" format(d,"%OS") # 00-60.99… Second as fractional ## [1] "30.579" for...

R Language • Date-time classes (POSIXct and POSIXlt)

Parsing strings into date-time objects

The functions for parsing a string into POSIXct and POSIXlt take similar parameters and return a similar-looking result, but there are differences in how that date-time is stored; see "Remarks." as.POSIXct("11:38", # time string format = "...

R Language • Date-time classes (POSIXct and POSIXlt)

Getting Started: Hello world!

Creating an HTML document and enabling knockout.js Create an HTML file and include knockout.js via a <script> tag. <!DOCTYPE html> <html> <head> <title>Hello world! (knockout.js)</title> </head> <body> <script src="https://cdnjs...

knockout.js • Getting started with knockout.js

Checking a single property

The quickCheck function tests a property on 100 random inputs. ghci> quickCheck prop_reverseDoesNotChangeLength +++ OK, passed 100 tests. If a property fails for some input, quickCheck prints out a counterexample. prop_reverseIsAlwaysEmpty xs = reverse xs == [] -- plainly not true for all ...

Haskell Language • QuickCheck

First Module and Hello World

To start coding in the first place, you have to right click your VBA Project in the left list and add a new Module. Your first Hello-World Code could look like this: Sub HelloWorld() MsgBox "Hello, World!" End Sub To test it, hit the Play-Button in your Toolbar or simply hit the...

VBA • Getting started with VBA

Each

Ruby has many types of enumerators but the first and most simple type of enumerator to start with is each. We will print out even or odd for each number between 1 and 10 to show how each works. Basically there are two ways to pass so called blocks. A block is a piece of code being passed which will...

Ruby Language • Iteration

Add shadows to text

Swift label1.layer.shadowOffset = CGSize(width: 3, height: 3) label1.layer.shadowOpacity = 0.7 label1.layer.shadowRadius = 2 Swift 3 label1.layer.shadowOffset = CGSize(width: 3, height: 3) label1.layer.shadowOpacity = 0.7 label1.layer.shadowRadius = 2 Objective-C label1.layer.shadowOffs...

iOS • UILabel

INSERT on specific columns

To do an insert on specific columns (as opposed to all of them) you must specify the columns you want to update. INSERT INTO USERS (FIRST_NAME, LAST_NAME) VALUES ('Stephen', 'Jiang'); This will only work if the columns that you did not list are nullable, identity, timestamp data type or compute...

Microsoft SQL Server • INSERT INTO

INSERT multiple rows of data

To insert multiple rows of data in SQL Server 2008 or later: INSERT INTO USERS VALUES (2, 'Michael', 'Blythe'), (3, 'Linda', 'Mitchell'), (4, 'Jillian', 'Carson'), (5, 'Garrett', 'Vargas'); To insert multiple rows of data in earlier versions of SQL Server, use "UNION ALL" like so: ...

Microsoft SQL Server • INSERT INTO