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Date: Wed, 28 Jun 2017 15:46:57 -0300
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To: Kalle Sommer Nielsen <kalle@php.net>
Cc: PHP Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Final variables
From: david.proweb@gmail.com (David Rodrigues)

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2017-06-28 13:59 GMT-03:00 Kalle Sommer Nielsen <kalle@php.net>:

> Hi David
>
> It seems like what you are looking for here is actually a constant[1].
> However constants do not support non scalar types, such as array or
> objects, what would really solve it on the objects side of things
> would be the introduction of a "readonly" keyword or similar, like
> that of C#[2]
>
=E2=80=8B=E2=80=8B

=E2=80=8BNot on reality.=E2=80=8B :(

The "final" keyworks make a "local scope" variable value "blocked to
rewrite" after instantiate it.
Okay, it sounds like a "const", and it is, but "not as we known it".

While constants are class member (or globals), a final variable is just a
variable blocked to rewrite, and it could be initialized with a new data
content every time that the context is called (eg. a function).

For instance (note that the parameter is "final", then I can't modify the
parameter variable, but it can receives a new value each time that I call
this function):

function write(final $message) { echo $message; }
write("Hello");
write("World");
// Write "Hello World" on ouput.

Or then:

function randomNumber() {
  final $number =3D mt_rand();
  echo $number;

  // $number =3D mt_rand_again(); // <-- will not be allowed!
}
randomNumber();
=E2=80=8B // Write "0.123"
randomNumber();
=E2=80=8B // Write "0.456"
=E2=80=8B



>
> [1] http://php.net/constants
> [2] https://docs.microsoft.com/en-us/dotnet/csharp/language-
> reference/keywords/readonly
>

--=20
David Rodrigues

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