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Comment by mdaniel | Hacker News Reader

For those unfamiliar with php, or its type annotations, why is adding type annotations a risky step? Do they become enforcing?

    function foo(string $bar) { ... }
    foo(1234) // kaboom?

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Yeah pretty much. It's risky because type checking produces fatal errors that aren't always easy to trap properly. You don't realize how much a code base relies on PHPs type coercion until you add annotations and watch it blow up, in often subtle ways.

"Subtle" is the keyword here.

I think your code will work because 1234 can be converted to a string. I think the trouble starts once you pass around objects.

It actually doesn't according to http://sandbox.onlinephpfunctions.com/code/8804b49c23d620228..., though different PHP versions could produce different results.

This works with PHP 7

<?php //Enter your code here, enjoy!

function foo(string $bar) { return $bar . $bar; }

echo foo(1234);

Wait? You mean you get runtime errors? That's well...good in a way but as you say dangerous on old code.

To get the true benefits of typing you should also run a static type analyzer.

Are there any for PHP?

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