Hi,
Multiple namespaces per file were introduced to allow certain workflows in PEAR
and frameworks like Symphony which can combine multiple classes and namespaces
in a single package.
They work like this:
namespace X;
...
namespace Y;
...
The problem is, no one thought of scoping "use" statements, so now those merged
files share their "use" imports, thus breaking all the code where collisions
occur.
Also we have the problems with name resolution of internal vs user classes and
autoloaders, discussed here.
And we also have the non-intuitive differentiation between resolving
functions/classes/constant which will most likely lead people to believe
functions/constants aren't supported in any way in namespaces (if they try, and
it doesn't work, they won't try second time).
Which leads me to the following proposal:
For PHP 5.3 we introduce namespaces with a very limited "safe" set of barebones
features, that we won't regret later for releasing and having to modify in a
non-BC way. It'll let people start porting their code and be ready for the full
featureset later on, which will be a proper superset of the 5.3 release:
1) We disable support for multiple namespaces per file as it is, as it can't be
used without ability to scope "use" statements as well.
2) We remove the statement "use" (regarding namespaces, not regarding
closures), until we get more feedback from the community on the exact preferred
resolution algorithms, and more thought is put to this.
For PHP 5.4 or 6:
1) Introduce file-level "use" statements with same syntax as now, but modified
resolution rules based on further discussion and feedback. And if someone is
about to say "we had plenty of discussion", well it's apparent we didn't have
enough given all the problems facing namespaces right now, or maybe not enough
of the constructive type of discussion.
2) Introduce ability to scope "use" and "namespace" statements with curly
brackets, so that multiple files can be safely merged without changing intent
(all file-level namespace can be converted with curly brackets, and the
existing curly bracket ones don't need to be converted), example:
namespace X {
use Y as Z {
...
}
}
namespace Y {
use X as Z {
...
}
}
Waiting for your feedback...
Regards,
Stan Vassilev
