Tutorial by Examples: re

In stable Rust you create a Box by using the Box::new function. let boxed_int: Box<i32> = Box::new(1);

If you try and create a recursive enum in Rust without using Box, you will get a compile time error saying that the enum can't be sized. // This gives an error! enum List { Nil, Cons(i32, List) } In order for the enum to have a defined size, the recursively contained value must be in...

As a way of subdividing Ada programs, packages may have so-called children. These can be packages, too. A child package has a special privilege: it can see the declarations in the parent package's private part. One typical use of this special visibility is when forming a hierarchy of derived types ...

Requirement is to check if in a form, ‘Online_date’ field is blank or filled. If it is blank, then fill it with current date, on form load. Controller calls ‘$form->createForm()” with type “folder”. In “FolderType”, event subscriber “FolderSubscriber” is added. Controller: $form =...

Let's say you have already created the custom Test Work Orders screen to manage test work orders in your Acumatica ERP application: There is already NoteID field declared in the TestWorkOrder DAC, managed on the Test Work Orders screen: [Serializable] public class TestWorkOrder : IBqlTable { ...

// logger middlerware that logs time taken to process each request func Logger(h http.Handler) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { startTime := time.Now() h.ServeHttp(w,r) endTime := time.Since(startTime) log...

func CORS(h http.Handler) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { origin := r.Header.Get("Origin") w.Header().Set("Access-Control-Allow-Origin", origin) if r.Method == "OPTIONS" { ...

func Authenticate(h http.Handler) http.Handler { return CustomHandlerFunc(func(w *http.ResponseWriter, r *http.Request) { // extract params from req // post params | headers etc if CheckAuth(params) { log.Println("Auth Pass") // pas...

func Recovery(h http.Handler) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request){ defer func() { if err := recover(); err != nil { // respondInternalServerError } }() h.ServeHTTP(w , r) }...

Usually output of a command goes to the terminal. Using the concept of Output redirection, the output of a command can be redirected to a file. So insted of displaying the output to the terminal it can be send to a file. '>' character is used for output redirection. $ pwd > file1 $ cat file...

The commands normally take their input from the standard input device keyboard. Using Input redirection concept, we can have their input redirected from a file. To redirect standard input from a file instead of the keyboard, the '<' character is used. $ cat file1 monday tuesday wednsday th...

AssertError The assert statement exists in almost every programming language. When you do: assert condition or: assert condition, message It's equivalent to this: if __debug__: if not condition: raise AssertionError(message) Assertions can include an optional message, and you can d...

You can capture the correct this using a closure. new Vue({ el:"#star-wars-people", data:{ people: null }, mounted: function(){ // Before executing the web service call, save this to a local variable var self = this; $.getJSON("http://swapi.co/api/peop...

new Vue({ el:"#app", data:{ foo: "bar" }, methods:{ // This is wrong! Arrow functions capture "this" lexically // and "this" will refer to the window. doSomething: () => this.foo = "baz" } })

Opening a stream fopen opens a file stream handle, which can be used with various functions for reading, writing, seeking and other functions on top of it. This value is of resource type, and cannot be passed to other threads persisting its functionality. $f = fopen("errors.log", "a...

Copying files copy copies the source file in the first argument to the destination in the second argument. The resolved destination needs to be in a directory that is already created. if (copy('test.txt', 'dest.txt')) { echo 'File has been copied successfully'; } else { echo 'Failed to ...

Steps: Create Empty .Net Core Web App: Go to wwwroot, and create a normal html page called Index.html: Configure Startup.cs to accept static files (this will require to add "Microsoft.AspNetCore.StaticFiles": "1.0.0" library in the “project.json” file): ...

public class Person { private final String salutation; private final String firstName; private final String middleName; private final String lastName; private final String suffix; private final Address address; private final boolean isFemale; private final boolean isEmployed; private final ...

After spending more than 5 hours, i found this easy solution: -To verify that the system has a CUDA-capable GPU, run the following command: lspci | grep -i NVIDIA You will see output similar to the following example (showing an NVIDIA Tesla K80/M60 card): -Disabling the nouveau driver: sudo...