Tutorial by Examples: p

Using expression in string literals

You can use curly braces to interpolate expressions into string literals: def f(x: String) = x + x val a = "A" s"${a}" // "A" s"${f(a)}" // "AA" Without the braces, scala would only interpolate the identifier after the $ (in this case f...

Types and Usage of Sets

Generally, sets are a type of collection which stores unique values. Uniqueness is determined by the equals() and hashCode() methods. Sorting is determined by the type of set. HashSet - Random Sorting Java SE 7 Set<String> set = new HashSet<> (); set.add("Banana"); set.ad...

Basic WordPress loop structure

Each time WordPress loads the page, it will run main loop. The loop is the way to iterate over all elements related to the page you are currently on. Main loop will work on a global WP_Query object. The query has a globalized method have_posts(), that allows us to loop through all results. Finally...

Alternative loop syntax

You can also use loop with curly brackets like this: if ( have_posts() ) { while ( have_posts() ) { the_post(); var_dump( $post ); } }

Handling no items in the loop

If you want to handle such scenario just add an if/else statement. if ( have_posts() ) : while ( have_posts() ) : the_post(); var_dump( $post ); endwhile; else : __('This Query does not have any results'); endif;

Block Scope

An identifier has block scope if its corresponding declaration appears inside a block (parameter declaration in function definition apply). The scope ends at the end of the corresponding block. No different entities with the same identifier can have the same scope, but scopes may overlap. In case o...

Function Prototype Scope

#include <stdio.h> /* The parameter name, apple, has function prototype scope. These names are not significant outside the prototype itself. This is demonstrated below. */ int test_function(int apple); int main(void) { int orange = 5; orange = test_function(oran...

File Scope

#include <stdio.h> /* The identifier, foo, is declared outside all blocks. It can be used anywhere after the declaration until the end of the translation unit. */ static int foo; void test_function(void) { foo += 2; } int main(void) { foo = 1; test_functi...

Plugins - Getting Started

The jQuery API may be extended by adding to its prototype. For example, the existing API already has many functions available such as .hide(), .fadeIn(), .hasClass(), etc. The jQuery prototype is exposed through $.fn, the source code contains the line jQuery.fn = jQuery.prototype Adding functio...

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...

Complex Example - jQuery UI Dynamicly Create Dialog

Generally, dialog relies on a div within the HTML. Sometimes you may want to create a dialog from scratch, programmatically. Here is an example of a complex modal dialog created dynamically with interactive functions. HTML <div id="users-contain" class="ui-widget"> &lt...

Builder Pattern / C# / Fluent Interrface

public class Email { public string To { get; set; } public string From { get; set; } public string Subject { get; set; } public string Body { get; set; } } public class EmailBuilder { private readonly Email _email; public EmailBuilder() { _email = ...

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...

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...

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...

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...

Reading or writing through a null pointer

int *ptr = nullptr; *ptr = 1; // Undefined behavior This is undefined behavior, because a null pointer does not point to any valid object, so there is no object at *ptr to write to. Although this most often causes a segmentation fault, it is undefined and anything can happen.

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...

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( _ ...

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}

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