章 25. Extension PossibilitiesAs shown in 图形 24-1 above, PHP can be extended primarily at three points: external modules, built-in modules, and the Zend engine. The following sections discuss these options. External ModulesExternal modules can be loaded at script runtime using the function dl(). This function loads a shared object from disk and makes its functionality available to the script to which it's being bound. After the script is terminated, the external module is discarded from memory. This method has both advantages and disadvantages, as described in the following table:
Third parties might consider using the extension tag in php.ini to create additional external modules to PHP. These external modules are completely detached from the main package, which is a very handy feature in commercial environments. Commercial distributors can simply ship disks or archives containing only their additional modules, without the need to create fixed and solid PHP binaries that don't allow other modules to be bound to them. | ||||||||||