Global variable in all functions of the class

Question

Usually when I want to pull a variable that is out of class, I use global $variavel, but wanted this variable to be accessible in all functions of the class, not to be needing to "pull" in all functions, how to do?

Answer 1

My understanding of the question is that it is necessary to store the connection data in a variable that can be accessed from any point of the application. A global variable is a solution to this but in fact it is not good to use it.

So the solution is to encapsulate the variable that is not global in a function by maintaining its state in a static way or using an approach considered more modern, but not necessarily better, encapsulating the variable in a static class.

Note that being static is the secret because it gives a lifespan for the variable equal to the application time, that is, the variable becomes available all the time exactly as the global variable is but has the advantage of the variable not being exposed directly creating ambiguities and conflicts with other local variables. It is better to have global functions or classes. Even this may not be the ideal solution, some would criticize this solution which is pragmatic.

class Conexao {
    private static $conexao = "dados da conexao aqui - classe";
    public static function PegaConexao() {
        return self::$conexao;
    }
}

function conexao(){
    static $conexao = "dados da conexao aqui - funcao";
    return $conexao;
}

class Uso {
    public function AbreBanco1() {
        echo conexao() . "\n";
    }
    public function AbreBanco2() {
        echo Conexao::PegaConexao();
    }
}

Uso::AbreBanco1(); //chama só para demonstrar
Uso::AbreBanco2(); //chama só para demonstrar

Behold working in the ideone. And in the repl it.. Also put on the Github for future reference.

As the question does not give details I can only show a generic solution but it is easy to adapt for use according to the specific need.

It doesn’t have to have both forms, I put the two to exemplify, obviously only one AbreBanco() would actually exist. And the contents of the variable will probably be another.

Answer 2

Create accessible variable for all functions of a class:

<?php

    class teste {

        /* construct */
        function __construct($variavel) {

            $this->global_variavel  = $variavel;

        }

        function checando_funcao() {

                echo $this->global_variavel;

        }

        function checando_funcao2() {

                echo $this->global_variavel;

        }

?>

• To run a test:

      //Criando uma nova instância
  
      $variavel = 'Meu texto!';
      $a = new teste($variavel);
  
      //Executando as duas funções com os mesmos valores de uma única variável "global"
      $a->checando();  
      $a->checando_funcao2();
  

Obs:

To ensure reverse compatibility, if PHP 5 cannot find a __Construct() for a given class, it will search for the old-fashioned constructor function, which has the same class name. Effectively, it means that the only case that can generate compatibility problems would be if the class has a method called __Construct() that is used for another purpose than not initializing the object.

Answer 3

To make a class variable member set the access modifier and then its name

public - is accessible by all class methods and outside it too.

protected - accessible only within the class and its derivatives.

private - accessible only detros of class methods.

class Teste{
   public $variavel = 'esse valor pode ser modificado externamente';

   public function foo(){
     echo $this->variavel;
   }
}