var declared site and take effect as new
- Value Type
- Reference types
Make the difference and new
Press new built-in functions 指定类型allocate memory length of zero value, returning a pointer, does not care about the type of internal configuration and initialization method.
The reference types 必须使用make函数创建,
the compiler will convert to make 目标类型a dedicated 创建函数(or instructions),
in order to ensure the completion of all the memory allocation and related properties have been initialized.
Of course, new functions can also be a reference type allocate memory, but it is not complete creation. A dictionary (map), for example, required memory it allocated only dictionary type itself (the actual package is a pointer), and does not allocate memory key-value store, there is no initialization hash buckets and other internal properties, so it does not work.
相比数字、数组等类型，引用类型拥有更复杂的存储结构。除分配内存外，它们还须初始化一系列属性，
诸如指针、长度，甚至包括哈希分布、数据队列等。