corba基础问题求助：关于in、out、inout、_retn

[忠向]

在TAO的源码中找到这段代码（来自TAO/tao/CORBA_String.h）:

/// For in parameter.
inline const character_type *in (void) const
{
return this->ptr_;
}

/// For inout parameter.
inline character_type *&inout (void)
{
return this->ptr_;
}

/// For out parameter.
inline character_type *&out (void)
{
s_traits::release (this->ptr_);
this->ptr_ = 0;
return this->ptr_;
}

/// For string of return type.
inline character_type *_retn (void)
{
character_type *temp = this->ptr_;
this->ptr_ = 0;
return temp;
}

in，inout，retn函数相对简单，我算是懂了，对out就不是很明白：this->ptr_被释放，后来又被赋值为0，再返回，岂不是被清零后返回一个空值了？