Tutorial by Examples: p

In the build.sbt file (or where the project is defined if it is in another location), add the following setting: scalacOptions += "-language:experimental.macros" For instance, a project might be defined like this: lazy val main = project.in(file(".")) // root project .se...

When the last command in an interactive bash instance is done, the evaluated PS1 variable is displayes. Before actually displaying PS1 bash looks whether the PROMPT_COMMAND is set. This value of this var must be a callable program or script. If this var is set this program/script is called BEFORE th...

PS2 is displayed when a command extends to more than one line and bash awaits more keystrokes. It is displayed too when a compound command like while...do..done and alike is entered. export PS2="would you please complete this command?\n" # now enter a command extending to at least two l...

When the select statement is executed, it displays the given items prefixed with a number and then displays the PS3 prompt: export PS3=" To choose your language type the preceding number : " select lang in EN CA FR DE; do # check input here until valid. break done

PS4 is displayes when bash is in debugging mode. #!/usr/bin/env bash # switch on debugging set -x # define a stupid_func stupid_func(){ echo I am line 1 of stupid_func echo I am line 2 of stupid_func } # setting the PS4 "DEBUG" prompt export PS4='\nDEBUG level:$SHLVL ...

When in the SBT console, to list all definable settings for a project: settings Or, to get a subproject's (for example, named webapp) settings: project webapp settings The first line above navigates into the specific subproject. To show the value of a specific setting (for instance, organi...

All that is needed to define a task is a declaration of it's type and a description: lazy val exampleTask = taskKey[Unit]("An example task that will return no value.") Because Unit is the type, this task is composed entirely of side-effects. Once defined, to implement actions: example...

This example covers some advanced features and use-cases for Exceptions. Examining the callstack programmatically Java SE 1.4 The primary use of exception stacktraces is to provide information about an application error and its context so that the programmer can diagnose and fix the problem. Som...

The whole point of MVVM is to separate layers containing logic from the view layer. On Android we can use the DataBinding Library to help us with this and make most of our logic Unit-testable without worrying about Android dependencies. In this example I'll show the central components for a stupid...

typealias SuccessHandler = (NSURLSessionDataTask, AnyObject?) -> Void This code block creates a type alias named SuccessHandler, just in the same way var string = "" creates a variable with the name string. Now whenever you use SuccessHandler, for example: func example(_ handler: S...

typealias Handler = () -> Void typealias Handler = () -> () This block creates a type alias that works as a Void to Void function (takes in no parameters and returns nothing). Here is a usage example: var func: Handler? func = {}

typealias Number = NSNumber You can also use a type alias to give a type another name to make it easier to remember, or make your code more elegant. typealias for Tuples typealias PersonTuple = (name: String, age: Int, address: String) And this can be used as: func getPerson(for name: Strin...

It is used to duplicate a git repository from gerrit to anyway. Configuration file is $GERRIT_INSTALL/etc/replication.config. Config file example to clone MyRepo from gerrit to backupServer [remote "backup"] url = ProjectUrlOnBackupServer/${name} #Example backup.some.org:/pub/git/${...

This plugin is mandatory to make Gerrit able to receive message from other services. As an example, it has to be install to use Sonar Gerrit plugin Install jar file under plugins folder Default configuration is sufficient

PermissionUtil is a simple and convenient way of asking for permissions in context. You can easily provide what should happen in case of all requested permissions granted (onAllGranted()), any request was denied (onAnyDenied()) or in case that a rational is needed (onRational()). Anywhere in your A...

By default, routes only respond to GET requests. You can change this behavior by supplying the methods argument to the route() decorator. from flask import request @app.route('/login', methods=['GET', 'POST']) def login(): if request.method == 'POST': do_the_login() else: ...

By default all enum values are resolved to numbers. Let's say if you have something like enum MimeType { JPEG, PNG, PDF } the real value behind e.g. MimeType.PDF will be 2. But some of the time it is important to have the enum resolve to a different type. E.g. you receive the value fr...

Open Jenkins default config file and add in JAVA_ARGS next key -Djenkins.install.runSetupWizard=false In Ubuntu 16 default file places in /etc/default/jenkins Create groovy file by path $JENKINS_HOME/init.groovy.d/basic-security.groovy In Ubuntu 16 Jenkins home directory places in /var/li...

(This assumes MySQL has been installed and that sudo is being used.) Generating a CA and SSL keys Make sure OpenSSL and libraries are installed: apt-get -y install openssl apt-get -y install libssl-dev Next make and enter a directory for the SSL files: mkdir /home/ubuntu/mysqlcerts cd /home...

Using canvas elements HTML provides the canvas element for building raster-based images. First build a canvas for holding image pixel information. var canvas = document.createElement('canvas'); canvas.width = 500; canvas.height = 250; Then select a context for the canvas, in this case two-di...