Tutorial by Examples: p

A lot of Vim users find the Esc too hard to reach, and end up finding another mapping that's easy to reach from the home row. Note that Ctrl-[ may be equivalent to Esc on an English keyboard, and is much easier to reach. jk inoremap jk <ESC> This one is really easy to trigger; just smash...

IPv4 To match IPv4 address format, you need to check for numbers [0-9]{1,3} three times {3} separated by periods \. and ending with another number. ^(?:[0-9]{1,3}\.){3}[0-9]{1,3}$ This regular expression is too simple - if you want to it to be accurate, you need to check that the numbers are be...

A Stopwatch instance can measure elapsed time over several intervals with the total elapsed time being all individual intervals added together. This gives a reliable method of measuring elapsed time between two or more events. Stopwatch stopWatch = new Stopwatch(); stopWatch.Start(); double d =...

Strict mode does not allow you to use duplicate function parameter names. function foo(bar, bar) {} // No error. bar is set to the final argument when called "use strict"; function foo(bar, bar) {}; // SyntaxError: duplicate formal argument bar

The simple answer, when asking how to use threads in Python is: "Don't. Use processes, instead." The multiprocessing module lets you create processes with similar syntax to creating threads, but I prefer using their convenient Pool object. Using the code that David Beazley first used to...

;Sends the keystroke for the letter "a" every 3 seconds. #Persistent SetTimer, SendLetterA, 3000 return SendLetterA() { Send, a }

This is an example of something that would have been straight up impossible with labels. If you execute the same label multiple times at the same time and they rely on variables that are being defined within them, they very likely interfere and cause unexpected behavior. Here is how to do it with f...

Pipe operators are used to pass parameters to a function in a simple and elegant way. It allows to eliminate intermediate values and make function calls easier to read. In F#, there are two pipe operators: Forward (|>): Passing parameters from left to right let print message = print...

If we have this dictionary: set alpha {alice {items {}} bob {items {}} claudia {items {}} derek {items {}}} And want to add "fork" and "peanut" to Alice's items, this code won't work: dict lappend alpha alice items fork peanut dict get $alpha alice # => items {} items f...

There are two ways to register a background page in the extension manifest. The scripts property In the common case, a background page doesn't require any HTML markup. We can register these kinds of background pages using the scripts property. In this case, a background page will be generated...

The ref keyword is used to pass an Argument as Reference. out will do the same as ref but it does not require an assigned value by the caller prior to calling the function. Ref Parameter :-If you want to pass a variable as ref parameter then you need to initialize it before you pass it as ref param...

In Swift, memory management is done for you automatically using Automatic Reference Counting. (See Memory Management) Allocation is the process of reserving a spot in memory for an object, and in Swift understanding the performance of such requires some understanding of the heap and the stack. The h...

dump prints the contents of an object via reflection (mirroring). Detailed view of an array: let names = ["Joe", "Jane", "Jim", "Joyce"] dump(names) Prints: ▿ 4 elements - [0]: Joe - [1]: Jane - [2]: Jim - [3]: Joyce For a dictionary: let attr...

Assume we want to create a data type Person, which has a first and last name, an age, a phone number, a street, a zip code and a town. We could write data Person = Person String String Int Int String String String If we want now to get the phone number, we need to make a function getPhone :: P...

defmodule ATest do use ExUnit.Case [{1, 2, 3}, {10, 20, 40}, {100, 200, 300}] |> Enum.each(fn {a, b, c} -> test "#{a} + #{b} = #{c}" do assert unquote(a) + unquote(b) = unquote(c) end end) end Output: . 1) test 10 + 20 = 40 (Test.Test) t...

With ASP.NET Core the Microsoft team also introduced the Options pattern, which allows to have strong typed options and once configured the ability to inject the options into your services. First we start with a strong typed class, which will hold our configuration. public class MySettings { ...

Sometimes you may want to output something by one program and input it into another program, but can't use a standard pipe. ls -l | grep ".log" You could simply write to a temporary file: touch tempFile.txt ls -l > tempFile.txt grep ".log" < tempFile.txt This work...

When testing for any of several equality comparisons: if a == 3 or b == 3 or c == 3: it is tempting to abbreviate this to if a or b or c == 3: # Wrong This is wrong; the or operator has lower precedence than ==, so the expression will be evaluated as if (a) or (b) or (c == 3):. The correct w...

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...

As of GHC 7.10, Applicative is a superclass of Monad (i.e., every type which is a Monad must also be an Applicative). All the methods of Applicative (pure, <*>) can be implemented in terms of methods of Monad (return, >>=). It is obvious that pure and return serve equivalent purposes, ...