PHP is a hybrid language. It however unevenly implements autoloading for classes only as of now. There are long-standing feature requests for supporting it with all language symbols. A more recent attempt to bring some systematization here was:
The ensuing php-dev discussion wasn't overly constructive. (Fatal errors provide a higher performance than autoloading a function). Backhandedly however to prevent functions becoming first class language constructs, due to them implying an unfavored coding paradigm.
Meanwhile PHP 5.6 introduced
use function imports - which however are aliases only, thus magnifying the dichotomy only further.
Why is it in shared.phar ?
shared.phar revisiting the big picture was a design goal, not repeating what's already there.
- Function autoloading here is a proof-of-concept mostly.
- Requires little additional effort for the autoloader.
- And implementing it in the map generator was a trivial by-product of doing things properly anyway.
It still can be be optionalized however, when unneeded.
How can I use it now?
See the attached example, which shows the common
class::__callStatic() workaround for current PHP versions. While such a class wrapper bemusingly gets autoloaded itself, it's probably only suitable for e.g. application-level plugin hook schemes.
The lack of core language support makes it unsuitable for autoloading namespaced functions. It can just shoehorn in global functions easily, or else required