runkit_constant_remove

(PECL runkit >= 0.7.0)

runkit_constant_remove — Remove/Delete an already defined constant

说明

runkit_constant_remove ( string $constname ) : bool

参数

constname: Name of constant to remove. Either a string indicating a global constant, or classname::constname indicating a class constant.

返回值

成功时返回 TRUE，或者在失败时返回 FALSE。

参见

define() - 定义一个常量
runkit_constant_add() - Similar to define(), but allows defining in class definitions as well
runkit_constant_redefine() - Redefine an already defined constant

User Contributed Notes

vladimir at bashkirtsev dot com 25-Nov-2014 09:08


At least under PHP 5.5.18 use of this function followed by constant redefinition like:



runkit_constant_remove("CONSTANT");

define("CONSTANT", "value");



may cause the constant to go into inconsistent state: from run-to-run var_dump(CONSTANT); may return NULL while $s = CONSTANT;  will cause "Fatal error: Allowed memory size of 1073741824 bytes exhausted (tried to allocate 1714381161 bytes)" (note that 1G of memory configured and it is still not enough). On some runs code behaves as expected.



I believe runkit doing some low level manipulation with pointers and perhaps it is just some form of bug. Just stay wary: fiddling around with PHP on low level likely to cause unexpected results.