Hello Friends!

Today we will learn About.

"How to autoload PHP classes the Composer way?"
                   or
"How to Implement PSR-4 in our project ?"










->First, create a working folder in xampp or wampserver directory.I have used xammp server, So i'm Creating Folder in htdocs folder .

->I am creating project1 name folder in htdocs.

->Open Command Prompt by clicking on start button and search command prompt.Another option press Home key + r and Type cmd and hit enter.

-> Go to working directory by using cd command.
   
->example :
        I am using window 10,  the initial path will be

        C:\Users\name_of_user>   

        My computer name is rahul, so my intial path is:

        C:\Users\rahul> 

-> Now ,I am going to working Directory by using this command.

C:\Users\rahul>cd /

Type cd / and hit enter.

->Now , Type cd xampp and hit enter again. path will display like this.

C:\>cd xampp

After hitting enter. Our path will be like this 

C:\xampp>

->Next, type in command prompt cd htdocs/project1 and hit enter. After hitting enter, path will show like this.

C:\xampp\htdocs\project1>

->It's time to initial Composer by using this command.

Composer init.

C:\xampp\htdocs\project1>composer init

hit enter

->After hitting  Enter. It will be asking some information like package name, version, description etc. Change it as per you need or hit enter to use default information. After this, a file will be created in your Project directory named composer.json.

->second command  

composer install

->Type composer install and hit  enter.

->After this, a folder named vendor will be created in working directory automatically.

->Now, open composer.json file In any code editor like as Sublime ,Nodepad++ ,PhpDesigner8, Atom etc. And
I am using Sublime Editor. 

->Next Step, Create an src directory in the project folder. That will hold class files.

->I have created src folder and created two files, first one is app.php and second is db.php .

->Define same namespace Acme in app.php and db.php. Now, write some simple code in app.php like this. 


 Next step:

->Add this code in composer.json;

{
  "autoload": {
    "psr-4": {
      "Acme\\":"src/"
    }
  }
}


a. We used The psr-4 key (This PSR describes a specification for autoloading classes from file paths ).
b. The namespace Acme points to the src/ directory.
c. The namespace has to end with \\. For example, "Acme\\".
d. You can replace the generic Acme with the name of your brand or website. 


->Now, create an index.php in the root directory.


-> Update the composer autoloader from the command line:

composer dumpautoload -o

->C:\xampp\htdocs\project1>composer dumpautoload -o  And hitting  Enter.

-> Set Path in your autoload.php by using Above command.

-> Add a file autoload.php in index.php like this:

require "vendor/autoload.php";

->Now, calling file using namespace and creating an object.


->Finally, i will show you how to add or run autoload composer code on my system.




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