What is a compiled variable?
How does it differ from a non-compiled-variable?
When engine encounters variable like $a what it usually does is it looks up current symbol table for an entry named 'a', and then takes zval* sitting there. However, since during the same scope the entry for $a will be the same (though not a value sitting there!), once found in can be stored so future calls to $a will not require looking up in the hash table. That's what CVs do. The reason, of course, is performance :)
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Stanislav Malyshev, Zend Software Architect
stas@zend.com http://www.zend.com/
(408)253-8829 MSN: stas@zend.com