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Date: Sun, 16 Aug 2020 22:33:54 +0100
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Subject: Re: [PHP-DEV] [RFC] Better string interpolation
From: rowan.collins@gmail.com (Rowan Tommins)

Hi Ilija,

On 14/08/2020 17:14, Ilija Tovilo wrote:
> I've been thinking about ways to improve string interpolation. String
> interpolation in PHP is currently pretty limited to say the least.


Thanks for putting together some thoughts on this.

My instinct is that rather than having a whole new syntax that's 
basically a tweak on "${expression}", we could take the opportunity to 
bring more features into the mix. If you think about it, string 
interpolation is basically an inline template syntax, so a lot of the 
features that are useful in template engines would be useful there.

Specifically:

1) modifiers; e.g. sprintf-style, f"Measure #0.2f{$value}" or 
template-style, f"Hello #{$name|escape}"

2) custom rules, like JavaScript's tagged templates [1], e.g. html"Hello 
#{$name}" == "Hello " . htmlspecialchars($name)


Put these together, and you can have variables escaped by default, and 
opted out via a modifier:

$tag = 'h1';
echo html"<#raw{$tag}>Hello #{$_GET['name']}</#raw{$tag}>";


If we took JS tagged templates as the inspiration, that would de-sugar 
to something like:

echo render_html_string(
     stringParts: [ '<', '>Hello ', '</', '>' ],
     expressions: [ $tag, $_GET['name'], $tag ],
     modifiers: [ ['raw'], [], ['raw'] ]
);


It will take a while to figure out the details, but I think a powerful 
feature like this is more worthy of adding new syntax.


[1] 
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals

Regards,

-- 
Rowan Tommins (né Collins)
[IMSoP]