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Subject: Re: [PHP-DEV] [RFC] PHP Attributes
From: smalyshev@gmail.com (Stanislav Malyshev)

Hi!

> https://wiki.php.net/rfc/attributes

I've read the proposal and I like the idea of reviving the attributes
idea and the simplicity of the approach.

I have the following questions for it:

- Namespacing. Since the attribute names are not processed in any way
according to spec, it may be rather hard to ensure attribute
requirements from different domains do not conflict, and we do not get
into the same problem we've got into with class names before we
implemented namespaces. How it is planned to address the issue?

- The expressions support is nice, however I'm not sure I understand
what PHP application is supposed to do with syntax trees? I.e. taking
the example in the RFC, if I got AST\Node representing <<test($a + $b >
0)>>, how do I use it? Would I implement mini-PHP-engine in PHP to
evaluate such an expression? Am I supposed to use some other
functionality to do it? It is unclear.
I don't think promoting reimplementing PHP expressions in a myriad of
different ways (which all would be subtly different and distinct from
how PHP understands such expressions) is not good, and if we expose
those trees we should also provide means to work with them. Otherwise
any advanced usage of the feature would mean basically reimplementing
PHP engine in PHP.
As a side note, my personal opinion is that for about 90% of use cases
expressions are not needed. For 90% of those which are needed, string +
some form of eval would cover it's use case since all the'd be doing is
evaluating the expression and checking the resulting value.

- As far as I can see, AST extension has no documentation except for
initial README. If it is going to end up in core, this needs to be
fixed. Preferably before it is merged into core.

- I would also consider moving AST namespace under \PHP since we have
this one reserved (unlike \AST which we did not reserve).

- Are attributes also allowed to apply to anonymous classes/functions?
Would the syntax still work in that case?

_ I also think <<...>> syntax is ugly and @attribute syntax would be
much better (and also is used in Java attributes and Python decorators).
That's my personal opinion though.

Thanks,
-- 
Stas Malyshev
smalyshev@gmail.com