Re: [Zend Engine 2] ZendEngine2/RFCs/002.txt

----- Original Message ----- From: "Stig Sæther Bakken" <ssb@alltheweb.com> To: <engine2@lists.zend.com>; <pear-dev@lists.php.net> Sent: Saturday, September 08, 2001 06.42am Subject: [Zend Engine 2] ZendEngine2/RFCs/002.txt > Introducing namespaces, it would make the most sense to change the > HTML_Table class to HTML:Table (class Table in the HTML namespace). > But that means the HTML/Table.php file would define symbols in the > "HTML" namespace, not "HTML:Table" as you might expect. My gut feeling is that I don't expect that. I expect the Table class to be defined in the HTML namespace. > Okay, we might live with that, but what if you also have some > functions or constants in HTML/Table.php? Since namespaces are > per-file, they'd also end up in the HTML namespace, which is > definitely what you'd be interested in (they could basically clash > with any other HTML_Something package. Good point. It might actually be a good idea for the Table class to be in its own (sub) namespace (i.e., PEAR:HTML:Table). > I can see four ways of dealing with this: > > 1. Allow mid-file namespaces changes that would allow a file to > contain: > > namespace Foo; > class Bar ... > namespace Foo:Bar; > constants ... > > 2. Change the entire PEAR class<->file scheme to a class<->namespace > scheme. This would be pretty ugly, we'd end up with fully > qualified class names such as "HTML_Table:Table" or "HTML:Table:Table". I think the 'HTML_Table'-type naming should go the way of the dodo. The 'HTML:Table:Table' naming might make sense -- or rather 'PEAR:HTML:Table:Table'. It's referencing the Table class in the 'PEAR:HTML:Table' namespace. > 3. Make a namespace "instantiatable" like I suggested a month or two > ago. This is what Perl/CPAN ended up doing, probably for the same > reasons I'm losing hair over this. :-) This might be a good way of doing it if PHP was more Perl-like. As it is, PHP is much more like C++ or Java in terms of OO syntax. The way Perl makes namespaces instantiable is way beyond the scope of what PHP can do, I think, and it would lead to horrible backwards-compatibility and migration problems. > 4. <your brilliant idea goes here> I wouldn't call them brilliant, but here are my ideas: 1) Emulate Java . . . kind of. Java has a classpath environment variable which is very akin to PHP's include_path. I suggest using the include_path for searching for a namespace. So PEAR's HTML_Table class would be referenced like 'PEAR:HTML:Table' -- the class, not the namespace. The DB class would be referenced like 'PEAR:DB'. (I do not suggest that root/super-classes in PEAR be in the global namespace.) Basically, then, a namespace is denoted by a directory. If you have a class in that namespace, you put it inside that directory in a file called ClassName.phpm (or whatever extension -- just a suggestion to have a special file extension for modules). Any functions or constants would be in a file called main.phpm -- and would always be loaded for that namespace. This has some problems, but with some collaboration, I think the problems could be ironed out. Result: $db = new PEAR:DB(...); 2) Have instantiable namespaces, but not automatically. For a namespace to be instantiable, it must have a class defined in it of the same name. Result: $db = new PEAR:DB(...); -------------------- The problem I'm finding here is that we cannot emulate either Java or Perl effectively. If we're looking for another language to set the example, I suggest we look elsewhere, like C++. Automagically loading files, however, as C++ doesn't do, is where we may need to be creative. Java allows absolutely nothing to be defined outside of a class. We could emulate Java except for the fact that PHP allows functions, constants, variables, and code outside of classes. We could require everything in a namespace to be in a single file, but this could get nasty and unwieldy. Perl allows a namespace to be instantiated, provided only that some class method blesses a variable (usually a hash) and returns a reference to it. PHP has no notion of blessing anything -- it's gone on for several years now with no notion of namespaces whatsoever. Adding namespace support to PHP, I think, will not be easy. Dean.