Re: [Zend Engine 2] Re: [PHP-DEV] Constants

At 02:42 PM 12/3/2001 -0600, Andrei Zmievski wrote:

On Mon, 03 Dec 2001, Andi Gutmans wrote: Personally I wouldn't write code which gives FOO_BAR and Foo_BAR two different meanings but I think you are right that it'd be better and I have an idea on how to do it which I'll lay out. We are only talking about global constants defined with define() as class constants are always case sensitive and they can distinguish what you mentioned above. That's fine for me. I want them for the keysym constants in PHP-GTK (like GDK_KEY_A and GDK_KEY_a). For now I hack around by using (GDK_KEY__A) for lowercase ones. Which sucks.

Oh OK.

There's one way I can think of in order to fix define(). It has advantages and disadvantages. The advantage is that all constant lookups will be much faster than they are today (no strtolower() and no memcmp()). The disadvantage is that defining constants will be much slower. What we would do is that instead of adding the name of the constant after an strtolower() into the constants hash we would do the following: - for case-sensitive constants: Add it with the exact same case as the definition. - for case-insensitive constants: Add all possible cases for the constant. That means that for a word of length L we'd add at most L*2 keys to the hash. This solution actually would work very well. It'd would fix the above problem and hash lookups would be faster. It would also be a step away from case-insensitive constants. It would of course make case-insensitive constant definitions much slower but as no C-extensions use them (especially after I nuke it) and only about 5 constants in Zend use them it should be fine (this is assuming that not many people use the third argument of define() which allows them to define case-insensitive constants). What about the idea of introducing case-insensitive hashes? Modifying hash function so that it hashes 'A' and 'a' into the same value.

Because some of the keys are case-insensitive and some aren't. Case insensitive hashes don't work if you want to mix the keys. In any case, I think the solution above is a good one because there are only 5 constants in the Zend Engine which are case-insensitive. Andi