Tutorial by Examples: w

Marshaling structs with private fields

As a good developer you have created following struct with both exported and unexported fields: type MyStruct struct { uuid string Name string } Example in Playground: https://play.golang.org/p/Zk94Il2ANZ Now you want to Marshal() this struct into valid JSON for storage in somet...

Go • JSON

Width vs Viewport

When we are using "width" with media queries it is important to set the meta tag correctly. Basic meta tag looks like this and it needs to be put inside the <head> tag. <meta name="viewport" content="width=device-width,initial-scale=1"> Why this is impo...

CSS • Media Queries

RippleDrawable

Ripple touch effect was introduced with material design in Android 5.0 (API level 21) and the animation is implemented by the new RippleDrawable class. Drawable that shows a ripple effect in response to state changes. The anchoring position of the ripple for a given state may be specified by call...

Android • Material Design

Download file from FTP server

My.Computer.Network.DownloadFile("ftp://server.my/myfile.txt", "donwloaded_file.txt") This command download myfile.txt file from server named server.my and saves it as donwloaded_file.txt into working directory. You can specify absolute path for downloaded file.

Visual Basic .NET Language • FTP server

Download file from FTP server when login required

My.Computer.Network.DownloadFile("ftp://srv.my/myfile.txt", "donwload.txt", "Peter", "1234") This command download myfile.txt file from server named srv.my and saves it as donwload.txt into working directory. You can specify absolute path for downloaded fil...

Visual Basic .NET Language • FTP server

Upload file to FTP server when login required

My.Computer.Network.UploadFile("doc.txt", "ftp://server.my/on_server.txt", "Peter", "1234") This command upload doc.txt file from working directory (you could specify absolute path if you want) to server named server.my. File stored on the server will be na...

Visual Basic .NET Language • FTP server

Searching For A Value In A Binary Search Tree With Recursion in C/C++

Structure for Binary Search Tree (BST) nodes: struct node { int data; node * left; node * right; } Search Algorithm // Check if a value exists in the tree bool BSTSearch(node * current, int value) { if (current->data == value) { return true; } e...

Recursion • Getting started with Recursion

Select dataset except where values are in this other dataset

--dataset schemas must be identical SELECT 'Data1' as 'Column' UNION ALL SELECT 'Data2' as 'Column' UNION ALL SELECT 'Data3' as 'Column' UNION ALL SELECT 'Data4' as 'Column' UNION ALL SELECT 'Data5' as 'Column' EXCEPT SELECT 'Data3' as 'Column' --Returns Data1, Data2, Data4, and Data5

SQL • EXCEPT

Viewing information for Bash built-ins

help <command> This will display the Bash help (manual) page for the specified built-in. For example, help unset will show: unset: unset [-f] [-v] [-n] [name ...] Unset values and attributes of shell variables and functions. For each NAME, remove the corresponding variable or ...

Bash • Getting started with Bash

RLMObject Base Model Class with Primary Key - Objective-C

An example of a RLMObject base model class that uses a primary key and some generic default properties. Subclasses can then set metadata specific to their needs. @interface BaseModel : RLMObject @property NSString *uuid; @property NSString *metadata; @end @implementation BaseModel + (N...

iOS • Realm

Page width and height

To get current page width and height (for any browser), e.g. when programming responsiveness: function pageWidth() { return window.innerWidth != null? window.innerWidth : document.documentElement && document.documentElement.clientWidth ? document.documentElement.clientWidth : document.bo...

JavaScript • Screen

On Windows

Default installation of R on Windows stored files (and thus library) on a dedicated folder per R version on program files. That means that by default, you would work with several versions of R in parallel and thus separate libraries. If this not what you want and you prefer to always work with a s...

R Language • Updating R and the package library

Return value when writing to a file object

In Python 2, writing directly to a file handle returns None: Python 2.x2.3 hi = sys.stdout.write('hello world\n') # Out: hello world type(hi) # Out: <type 'NoneType'> In Python 3, writing to a handle will return the number of characters written when writing text, and the number of by...

Python Language • Incompatibilities moving from Python 2 to Python 3

Basic annotation autowiring

Interface: public interface FooService { public int doSomething(); } Class: @Service public class FooServiceImpl implements FooService { @Override public int doSomething() { //Do some stuff here return 0; } } It should be noted that a class must imple...

spring • Creating and using beans

Usage (with condition) in assignment

def results = [] (1..4).each{ def what = (it%2) ? 'odd' : 'even' results << what } assert results == ['odd', 'even', 'odd', 'even'] Here, the if-condition (in (parentheses)) is slightly more complex than just testing for existence/Groovy-Truth.

groovy • Ternary and Elvis Operators

1. Install and manage versions of Ruby with rbenv

The easiest way to install and manage various versions of Ruby with rbenv is to use the ruby-build plugin. First clone the rbenv repository to your home directory: $ git clone https://github.com/rbenv/rbenv.git ~/.rbenv Then clone the ruby-build plugin: $ git clone https://github.com/rbenv/rub...

Ruby Language • rbenv

General approach to debug when building with Make

Suppose the make fails: $ make Launch it instead with make VERBOSE=1 to see the commands executed. Then directly run the linker or compiler command that you'll see. Try to make it work by adding necessary flags or libraries. Then figure out what to change, so CMake itself can pass correct argum...

cmake • Test and Debug

Enums with static fields

If your enum class is required to have static fields, keep in mind they are created after the enum values themselves. That means, the following code will result in a NullPointerException: enum Example { ONE(1), TWO(2); static Map<String, Integer> integers = new HashMap<>(); ...

Java Language • Enums

Create your first web application

GWT ships with a command line utility called webAppCreator that automatically generates all the files you’ll need in order to start a GWT project. It also generates Eclipse project files and launch config files for easy debugging in GWT’s development mode. You can create a new demo application in a...

gwt • Getting started with gwt

Adding behaviour by adding classes without touching existing code

import java.util.ArrayList; import java.util.List; import static java.lang.System.out; public class PolymorphismDemo { public static void main(String[] args) { List<FlyingMachine> machines = new ArrayList<FlyingMachine>(); machines.add(new FlyingMachine())...

Java Language • Polymorphism