Create instance from a variable

Question

I want to do this:

private static function parserLib() {
    return USE_XML ? 'XmlParser' : 'IdfParser';
}

static function create($arr = []) {
    return new ${self::parserLib()}($arr);
}

I've tried with this:

 new ${'XmlParser'}($test);

Don't work.

This works:

 $var = 'XmlParser';
 new $var($test);

Why is not possible to use the {} to use the value retrieved from a method?

FallDi · Accepted Answer · 2015-11-15 18:09:23Z

1

$var = 'XmlParser';
new $var($test);

You define variable $var and used it value to instance class.

new ${'XmlParser'}($test);

${'XmlParser'} is means get value of variable XmlParser, but you have not such variable.

You try get value of undefined variable and in the result got such error "PHP Notice: Undefined variable: XmlParser".

If you define variable XmlParser it will be works

class XmlParser {}
$XmlParser = 'XmlParser';
new ${'XmlParser'}($test);

Also please read about php string complex syntax

answered Nov 15, 2015 at 18:09

FallDi

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