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This is confusing. Why not just always use parentheses?

Parentheses are used to enclose the arguments of function calls. Using them for procedure calls can cause unexpected problems. Because they can introduce bugs, both at run-time by passing a possibly unintended value to the procedure, and at compile-time by simply being invalid syntax. Run-time Re...

Lexicographical comparison

Two std::strings can be compared lexicographically using the operators ==, !=, <, <=, >, and >=: std::string str1 = "Foo"; std::string str2 = "Bar"; assert(!(str1 < str2)); assert(str > str2); assert(!(str1 <= str2)); assert(str1 >= str2); assert...

Attach object to another existing object (association)

It's possible to attach an object to an existing object as if there was a new property. This is called association and allows one to extend existing objects. It can be used to provide storage when adding a property via a class extension or otherwise add additional information to an existing object. ...

Augmenting methods using Method Swizzling

The Objective-C runtime allows you to change the implementation of a method at runtime. This is called method swizzling and is often used to exchange the implementations of two methods. For example, if the methods foo and bar are exchanged, sending the message foo will now execute the implementation...

Searching for a Substring

To search if a String contains a substring, do the following: NSString *myString = @"This is for checking substrings"; NSString *subString = @"checking"; BOOL doesContainSubstring = [myString containsString:subString]; // YES If targeting iOS 7 or OS X 10.9 (or earlier)...

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...

Block Typedefs

typedef double (^Operation)(double first, double second); If you declare a block type as a typedef, you can then use the new type name instead of the full description of the arguments and return values. This defines Operation as a block that takes two doubles and returns a double. The type can b...

Procedure Names

Procedures do something. Name them after what they're doing, using a verb. If accurately naming a procedure is not possible, likely the procedure is doing too many things and needs to be broken down into smaller, more specialized procedures. Some common VBA naming conventions go thus: For all Pr...

Basic Component

Given the following HTML file: index.html <!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <title>React Tutorial</title> <script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.2.1/react.js"></script>...

Structs cannot inherit

Unlike classes, structures cannot inherit: class MyView: NSView { } // works struct MyInt: Int { } // error: inheritance from non-protocol type 'Int' Structures, however, can adopt protocols: struct Vector: Hashable { ... } // works

Extractor Infix notation

If a case class has exactly two values, its extractor can be used in infix notation. case class Pair(a: String, b: String) val p: Pair = Pair("hello", "world") val x Pair y = p //x: String = hello //y: String = world Any extractor that returns a 2-tuple can work this way....

For-in loop

The for-in loop allows you to iterate over any sequence. Iterating over a range You can iterate over both half-open and closed ranges: for i in 0..<3 { print(i) } for i in 0...2 { print(i) } // Both print: // 0 // 1 // 2 Iterating over an array or set let names = [&quo...

Repeat-while loop

Similar to the while loop, only the control statement is evaluated after the loop. Therefore, the loop will always execute at least once. var i: Int = 0 repeat { print(i) i += 1 } while i < 3 // 0 // 1 // 2

while loop

A while loop will execute as long as the condition is true. var count = 1 while count < 10 { print("This is the \(count) run of the loop") count += 1 }

Using Range with various Linq methods

You can use the Enumerable class alongside Linq queries to convert for loops into Linq one liners. Select Example Opposed to doing this: var asciiCharacters = new List<char>(); for (var x = 0; x < 256; x++) { asciiCharacters.Add((char)x); } You can do this: var asciiCharacter...

Remove value from array

When you need to remove a specific value from an array, you can use the following one-liner to create a copy array without the given value: array.filter(function(val) { return val !== to_remove; }); Or if you want to change the array itself without creating a copy (for example if you write a fun...

Benefits of Using Composer

Composer tracks which versions of packages you have installed in a file called composer.lock, which is intended to be committed to version control, so that when the project is cloned in the future, simply running composer install will download and install all the project's dependencies. Composer de...

Nesting Components

A lot of the power of ReactJS is its ability to allow nesting of components. Take the following two components: var React = require('react'); var createReactClass = require('create-react-class'); var CommentList = reactCreateClass({ render: function() { return ( <div className...

"Exclusive or" Operator

The operator for an "exclusive or" (for short XOR) is: ^ This operator returns true when one, but only one, of the supplied bools are true. true ^ false // Returns true false ^ true // Returns true false ^ false // Returns false true ^ true // Returns false

Forward Declarations

It's possible to declare protocol name without methods: @protocol Person; use it your code (class definition, etc): @interface World : NSObject @property (strong, nonatomic) NSArray<id<some>> *employees; @end and later define protocol's method somewhere in your code: @protocol...

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