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Date: Sun, 29 Mar 2020 16:50:24 -0500
To: "php internals" <internals@lists.php.net>
Content-Type: text/plain
Subject: Re: [PHP-DEV] [RFC] switch expression
From: larry@garfieldtech.com ("Larry Garfield")

On Sun, Mar 29, 2020, at 4:04 PM, Ilija Tovilo wrote:
> > Having two syntaxes for one keyword is not a good idea,
> 
> We're already doing that. What about classes vs anonymous objects?
> Functions vs closures?
> They're using the same keywords. There's no confusion.
> 
> Ilija

There's subtle and important differences there.

An anonymous function is still a function, in that it is a routine that takes input and produces output.  A closure is, technically, an anonymous function that has imported variables from its parent scope.

Anonymous classes (not anonymous objects) are implemented as, legitimately, classes; they just have an arbitrary internal name.  The object that results can be used exactly like any other object, by design.

I don't believe that's the case here, however.  `switch` is a language construct for a *statement*, which branches the flow of control of the program.

What you're proposing is a language construct for an *expression*, which evaluates depending on internal logic to a different value.

Those are sufficiently distinct that I agree they should have distinct keywords.  Plus, the internal syntax is non-trivial to switch back and forth between (break vs not, etc.), so it is misleading for people to present them as two slight variants on the same thing; they're really quite distinct, and that's OK.

My recommendation would be to just borrow Rust's keyword:

$result = match ($var) {
  $expression => $expression;
  $expression => $expression;
  $expression => $expression;
  default => $expression;
}

--Larry Garfield