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Why doesn't var_dump work with DOMDocument objects, while print($dom->saveHTML()) produces output?
Why doesn't var_dump work with DOMDocument objects, while print($dom->saveHTML()) produces output?
Update: As of PHP 5.4.1 you can finally var_dump DOM objects. See https://gist.github.com/2499678
It's a bug:
It has nothing to do with any interfaces and in fact is very simple. var_dump shows only those class properties that have been declared by their developers by calling such C-functions as
ZEND_API int zend_declare_property(...)
ZEND_API int zend_declare_property_null(...)
ZEND_API int zend_declare_property_bool(...)
ZEND_API int zend_declare_property_long(...)
ZEND_API int zend_declare_property_double(...)
ZEND_API int zend_declare_property_string(...)
ZEND_API int zend_declare_property_stringl(...)
For instance, the properties of the class Exception are declared in the file Zend/zend_exceptions.c like this
zend_declare_property_string(default_exception_ce, "message", sizeof("message")-1, "", ZEND_ACC_PROTECTED TSRMLS_CC);
zend_declare_property_string(default_exception_ce, "string", sizeof("string")-1, "", ZEND_ACC_PRIVATE TSRMLS_CC);
zend_declare_property_long(default_exception_ce, "code", sizeof("code")-1, 0, ZEND_ACC_PROTECTED TSRMLS_CC);
zend_declare_property_null(default_exception_ce, "file", sizeof("file")-1, ZEND_ACC_PROTECTED TSRMLS_CC);
zend_declare_property_null(default_exception_ce, "line", sizeof("line")-1, ZEND_ACC_PROTECTED TSRMLS_CC);
zend_declare_property_null(default_exception_ce, "trace", sizeof("trace")-1, ZEND_ACC_PRIVATE TSRMLS_CC);
zend_declare_property_null(default_exception_ce, "previous", sizeof("previous")-1, ZEND_ACC_PRIVATE TSRMLS_CC);
All these functions then call
ZEND_API int zend_declare_property_ex(zend_class_entry *ce, const char *name, ...
which updates the property list. Then comes the var_dump in ext/standard/var.c and looks them up by calling php_object_property_dump which enumerates them through the same property list. You see the intentionally exposed inner structure.
The developers of the DOM extension just have ch