Tyson Andre wrote:
Hi internals,
In PHP, variables are currently scoped to the function scope, and
can't be scoped to a block scope. This makes it difficult to reason
about how a variable will actually be used at a glance, especially in
long functions, or top-level statement lists of a file.
(or how the variable was originally intended to be used)
The function scope lifetime of variables in PHP is similar to how
JavaScript treated variables with `var`, before the introduction of
the `let` statement in JS:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/let
Would there be any interest in adding something similar to this in PHP?
I'd definitely like this, and this has also been proposed as a possible future
direction in the "Variable declarations before usage" RFC: https://wiki.php.net/rfc/declare_vars
For reasons of backwards compatibility and avoiding having to add new keywords,
we may want to consider using "var", instead of "let".
Starting with scoped variables could also evolve into requiring variables
to be declared using the optional "declare(declare_vars=1)" directive from
the above proposal.
For me, perhaps the most interesting spin-off of adding optional variable
declarations would be the possibility of using typed local variables (also
suggested in the above proposal), maybe something like:
declare(typed_vars=1); // In case we want opt-in
var $message = "Test"; // No type declaration needed, type inferred as "string"
...
$message = null; // Error $message is of type string
$message = new SomeMessage(); // Error $message is of type string
If we don't have an initialiser, we might specify the type explicitly (note:
I'm here talking about what explicitly declaring variables may be used for
in the future, I'm not proposing this now):
var ?string $message;
...
$message = null; // OK
$message = "Test"; // OK
$message = new Something(); // Error, $message is of type ?string
Regards,
Terje
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