Tutorial by Examples: s

Calculate Content Bounds (for i.e. dynamic cell heights)

A common use case for wanting to calculate the frame a label will take up is for sizing table view cells appropriately. The recommended way of doing this is using the NSString method boundingRectWithSize:options:attributes:context:. options takes String drawing options: NSStringDrawingUsesLineFr...

iOS • UILabel

Show week of the year

The following code will show week of the year number on the left side of the datepicker. By default the week start on Monday, but it can be customized using firstDay option. The first week of the year contains the first Thursday of the year, following the ISO 8601 definition. <input type="t...

jQuery UI Library • Datepicker

Initial Usage Example

jquery-ui-rotatable is a plugin for jQuery UI that works in a similar way to Draggable and Resizable, without being as full-featured. By default, it puts a small rotation icon in the bottom left of whatever element you want to make rotatable. <html> <head> <title>My Ro...

jQuery UI Library • jQuery UI Rotatable Plug-in

Use requestAnimationFrame to fade in element

View jsFiddle: https://jsfiddle.net/HimmatChahal/jb5trg67/ Copy + Pasteable code below: <html> <body> <h1>This will fade in at 60 frames per second (or as close to possible as your hardware allows)</h1> <script> // Fad...

JavaScript • requestAnimationFrame

Object.assign

The Object.assign() method is used to copy the values of all enumerable own properties from one or more source objects to a target object. It will return the target object. Use it to assign values to an existing object: var user = { firstName: "John" }; Object.assign(user, {last...

JavaScript • Objects

The Flags attribute

With the <Flags> attribute, the enum becomes a set of flags. This attribute enables assigning multiple values to an enum variable. The members of a flags enum should be initialized with powers of 2 (1, 2, 4, 8...). Module Module1 <Flags> Enum Material Wood = 1 ...

Visual Basic .NET Language • Enum

Committing at a specific date

git commit -m 'Fix UI bug' --date 2016-07-01 The --date parameter sets the author date. This date will appear in the standard output of git log, for example. To force the commit date too: GIT_COMMITTER_DATE=2016-07-01 git commit -m 'Fix UI bug' --date 2016-07-01 The date parameter accepts t...

Git • Committing

Devise Controller Filters & Helpers

To set up a controller with user authentication using devise, add this before_action: (assuming your devise model is 'User'): before_action :authenticate_user! To verify if a user is signed in, use the following helper: user_signed_in? For the current signed-in user, use this helper: current_us...

Ruby on Rails • User Authentication in Rails

Destructuring an array

6 An array can be destructured when being assigned to a new variable. const triangle = [3, 4, 5]; const [length, height, hypotenuse] = triangle; length === 3; // → true height === 4; // → true hypotneuse === 5; // → true Elements can be skipped const [,b,,c] = [1, 2, 3, 4]; co...

JavaScript • Arrays

Reduce an array to chained promises

This design pattern is useful for generating a sequence of asynchronous actions from a list of elements. There are two variants : the "then" reduction, which builds a chain that continues as long as the chain experiences success. the "catch" reduction, which builds a chain t...

JavaScript • Promises

Bitwise operators

Bitwise operators perform operations on bit values of data. These operators convert operands to signed 32-bit integers in two's complement. Conversion to 32-bit integers Numbers with more than 32 bits discard their most significant bits. For example, the following integer with more than 32 bits i...

JavaScript • Bitwise operators

No return statement for a function with a non-void return type

Omitting the return statement in a function which is has a return type that is not void is undefined behavior. int function() { // Missing return statement } int main() { function(); //Undefined Behavior } Most modern day compilers emit a warning at compile time for this kind o...

C++ • Undefined Behavior

Modifying a string literal

C++11 char *str = "hello world"; str[0] = 'H'; "hello world" is a string literal, so modifying it gives undefined behaviour. The initialisation of str in the above example was formally deprecated (scheduled for removal from a future version of the standard) in C++03. A num...

C++ • Undefined Behavior

Listening to Changes of contenteditable

Events that work with most form elements (e.g., change, keydown, keyup, keypress) do not work with contenteditable. Instead, you can listen to changes of contenteditable contents with the input event. Assuming contenteditableHtmlElement is a JS DOM object that is contenteditable: contenteditableH...

JavaScript • execCommand and contenteditable

Switch off properties during macro execution

It is best practice in any programming language to avoid premature optimization. However, if testing reveals that your code is running too slowly, you may gain some speed by switching off some of the application’s properties while it runs. Add this code to a standard module: Public Sub SpeedUp( _ ...

excel-vba • VBA Best Practices

Spreadsheet to dict of DataFrames

with pd.ExcelFile('path_to_file.xls) as xl: d = {sheet_name: xl.parse(sheet_name) for sheet_name in xl.sheet_names}

pandas • Pandas IO tools (reading and saving data sets)

Read a specific sheet

pd.read_excel('path_to_file.xls', sheetname='Sheet1') There are many parsing options for read_excel (similar to the options in read_csv. pd.read_excel('path_to_file.xls', sheetname='Sheet1', header=[0, 1, 2], skiprows=3, index_col=0) # etc.

pandas • Pandas IO tools (reading and saving data sets)

Rename Folders

To rename a folder from oldName to newName git mv directoryToFolder/oldName directoryToFolder/newName Followed by git commit and/or git push If this error occurs: fatal: renaming 'directoryToFolder/oldName' failed: Invalid argument Use the following command: git mv directoryToFolder/oldN...

Git • Renaming

Simple lambda expressions

// A simple adder function defined as a lambda expression. // Unlike with regular functions, parameter types often may be omitted because the // compiler can infer their types let adder = |a, b| a + b; // Lambdas can span across multiple lines, like normal functions. let multiplier = |a: i32, ...

Rust • Closures and lambda expressions

Simple closures

Unlike regular functions, lambda expressions can capture their environments. Such lambdas are called closures. // variable definition outside the lambda expression... let lucky_number: usize = 663; // but the our function can access it anyway, thanks to the closures let print_lucky_number = ...

Rust • Closures and lambda expressions