Anonymous Functions

https://phptherightway.com/pages/Functional-Programming.html

Mick’s example

public function test3()
    {
        $fixed = 27;
        $hi = 'hi';

        //the variable fixed is stored at the function at this point
        $addOneToFixed = function($hi) use ($fixed){
            if($hi === 'hi'){
                return $fixed +1;
            }
        };

        $fixed = 28000;
        dd($addOneToFixed($hi));

    }

The variable inside () is passed when the function is called, the variable in the use is actually fixed when the function is defined

Assigning to Variables

$addition=function($arg1,$arg2){

return 'sum = '.$arg1+$arg2;

};

Using anonyomous function as a callback

array_map can be passed a callback

$new_array = array_map(function($num){

return $num*$num;
}, $num_array);

Creating Closures with anonymous functions

A closure is same as the lambda apart from it can access the variable which is created outside of its scope or are not in its perimeter.

//define a regular variable

$user='Peter';

//create a closure using anonymous function

$message=function() use ($user){

echo 'hello'. $user;

}

Altering the $user variable in the function will not change it outside.

The Strategy Pattern

Define a family of algorithims.

Logger interface. 3 Different logging classes implement this interface.

Laravel From Scratch 5.7

21 Service Container and Auto-Resolution

Auto resolving when type hinting - looks in the Service Container (basically a big list of key-value pairs). Can use app(Filesystem::class)

Putting things into the toybox (Service Container):

app()->bind('example', function(){
  return new \App\Example;
});

if you want a singleton:

app()->singleton('example', function(){
  return new \App\Example;
});

to retrieve:

app('example')

You don’t need to bind, if you use the class path:

app('App\Example');

If Example depends on a Foo, inject this into it’s constructor. This will get auto resolved.

When to use the Service Container.

22 Service Providers

• need to be registered in app.php
• register method is where you bind
• Laravel runs through all the service providers and calles register
• It then runs through again and calls boot

Can just add to AppServiceProvider or create a dedicated provider (must add to app.php).

Can bind an interface to a class.

PSR-4 Autoloading

https://laracasts.com/lessons/psr-4-autoloading

Laracasts example:

app - Laracasts

namespace is from app folder

### Autoload

“psr-4”:{ “Laracasts\”;”app/Laracasts” }

## Creating class from name

```$modelClass = 'App\Models\\' . $type;
 $modelClass::query()->where('updated_at', '>=', $timewindow)->first();