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Creating a dictionary: set mydict [dict create a 1 b 2 c 3 d 4] dict get $mydict b ; # returns 2 set key c set myval [dict get $mydict $key] puts $myval # remove a value dict unset mydict b # set a new value dict set mydict e 5 Dictionary keys can be nested. dict set mycars mustang colo...

Use a mutex to synchronise access to a variable which is accessed from multiple threads: counter = 0 counter_mutex = Mutex.new # Start three parallel threads and increment counter 3.times.map do |index| Thread.new do counter_mutex.synchronize { counter += 1 } end end.each(&:joi...

The static keyword is used on a class, method, or field to make them work independently of any instance of the class. Static fields are common to all instances of a class. They do not need an instance to access them. Static methods can be run without an instance of the class they are in. However...

Abstraction is a process of hiding the implementation details and showing only functionality to the user. An abstract class can never be instantiated. If a class is declared as abstract then the sole purpose is for the class to be extended. abstract class Car { abstract void tagLine(); } ...

Synchronized modifier is used to control the access of a particular method or a block by multiple threads. Only one thread can enter into a method or a block which is declared as synchronized. synchronized keyword works on intrinsic lock of an object, in case of a synchronized method current objects...

A variable which is declared as transient will not be serialized during object serialization. public transient int limit = 55; // will not persist public int b; // will persist

Java SE 1.2 strictfp modifier is used for floating-point calculations. This modifier makes floating point variable more consistent across multiple platforms and ensure all the floating point calculations are done according to IEEE 754 standards to avoid errors of calculation (round-off errors), ov...

This worked for me to move from Ubuntu 12.04 (Jenkins ver. 1.628) to Ubuntu 16.04 (Jenkins ver. 1.651.2). I first installed Jenkins from the repositories. Stop both Jenkins servers Copy JENKINS_HOME (e.g. /var/lib/jenkins) from the old server to the new one. From a console in the new serve...

Create a new project.json and example Program.cs: dotnet new Restore needed packages: dotnet restore Compile and run the example: dotnet run

Go to the project.json directory and publish: dotnet publish It will print the output directory of the operation, enter the directory and run the published project: dotnet <project output>.dll The default folder will be: <project root>/bin/<configuration>/<target framewo...

Simple example Assuming that the "HelloWorld.java" contains the following Java source: public class HelloWorld { public static void main(String[] args) { System.out.println("Hello world!"); } } (For an explanation of the above code, please refer to Gettin...

Standard You don't need to create the variable, but it's a good practice as you can use that variable with clearInterval to stop the currently running interval. var int = setInterval("doSomething()", 5000 ); /* 5 seconds */ var int = setInterval(doSomething, 5000 ); /* same thing, no qu...

If the program is short, you can include it in the command that runs awk: awk -F: '{print $1, $2}' /etc/passwd In this example, using command line switch -F: we advise awk to use : as input fields delimiter. Is is the same like awk 'BEGIN{FS=":"}{print $1,$2}' file Alternativelly, ...

Setting up an instance To use Realm you first need to obtain an instance of it. Each Realm instance maps to a file on disk. The most basic way to get an instance is as follows: // Create configuration RealmConfiguration realmConfiguration = new RealmConfiguration.Builder(context).build(); // O...

Prolog tries alternative clauses for a predicate in the order of appearance: likes(alice, music). likes(bob, hiking). // Either alice likes music, or bob likes hiking will succeed. The disjunction (OR) operator ; can be used to express this in one rule: likes(P,Q) :- ( P = alice , Q = ...

Sometimes it is desirable to prevent Prolog from backtracking into alternative solutions. The basic tool available to the programmer to stop prolog from continuing futher in its backtrack is the cut operator. consider the following. % (percent signs mean comments) % a is the parent of b, c, and d....

Rebar3 is written in Erlang, so you need Erlang to run it. It is available as a binary that you can download and run. Just fetch the nightly build and give it execution permissions: $ wget https://s3.amazonaws.com/rebar3/rebar3 && chmod +x rebar3 Place this binary in a convenient place a...

As Rebar3 is free, open source and written in Erlang, it's possible to simply clone and build it from the source code. $ git clone https://github.com/erlang/rebar3.git $ cd rebar3 $ ./bootstrap This will create the rebar3 script, which you can put on your PATH or link to /usr/local/bin as expl...

To bootstrap a new Erlang project, simply choose the template you want to use from the list. The available templates can be retrieved by the following command: $ rebar3 new app (built-in): Complete OTP Application structure cmake (built-in): Standalone Makefile for building C/C++ in c_src escr...

We can always use ListView or RecyclerView for selection from list of items, but if we have small amount of choices and among those choices we want user to select one, we can use AlertDialog.Builder setAdapter. private void showDialog() { AlertDialog.Builder builder = new AlertDia...