php内核：include与require区别的根本

php手册告诉我们，require和include只是在对错误信息的处理上有所差别。可是自己记性不好，经常忘记，所以今天就把php内核源码认真的查看了一下，具体的过程记录在这里了：

http://code.google.com/p/cyy0523xc/source/browse/trunk/%E5%AD%A6%E4%B9%A0/PHP%E5%86%85%E6%A0%B8_include_and_require.txt

关键是在zend_language_scanner.l文件中的这段代码：

// require与include的差别只是在此：错误信息的显示级别

if (type==ZEND_REQUIRE) { //require时

zend_message_dispatcher(ZMSG_FAILED_REQUIRE_FOPEN, file_handle->filename TSRMLS_CC);

zend_bailout();

} else {

zend_message_dispatcher(ZMSG_FAILED_INCLUDE_FOPEN, file_handle->filename TSRMLS_CC);

}

而zend_message_dispatcher调用的其实是main/main.c文件中的php_message_handler_for_zend函数，里面有：

//include输出错误信息时的级别为：E_WARNING
case ZMSG_FAILED_INCLUDE_FOPEN:
php_error_docref("function.include" TSRMLS_CC, E_WARNING, "Failed opening '%s' for inclusion (include_path='%s')", php_strip_url_passwd((char *) data), STR_PRINT(PG(include_path)));
break;
//require输出错误信息时的级别为：E_COMPILE_ERROR
case ZMSG_FAILED_REQUIRE_FOPEN:
php_error_docref("function.require" TSRMLS_CC, E_COMPILE_ERROR, "Failed opening required '%s' (include_path='%s')", php_strip_url_passwd((char *) data), STR_PRINT(PG(include_path)));
break;

显然，include使用E_WARNING级别来显示错误信息，而require使用E_COMPILE_ERROR基本来显示错误信息。