直营与非直营快递公司然而你一定会发现，顺丰、京东和德邦之类的快递基本不会放在驿站，不是送货上门就是放在快递柜。没错，这就是快递公司的差异。顺丰、京东和德邦物流这几家，都是典型的直营快递。所谓直营，就是这些快递公司在每个层级的中转站、分拣站、派送网点都是由自己负责开设和运营的，且一般只服务于自家快递公司。
Rust offers a powerful trait system that allows us to write highly polymorphic and reusable code. However, the restrictions of coherence and orphan rules have been a long standing problem and a source of confusion, limiting us from writing trait implementations that are more generic than they could have been.
。新收录的资料对此有专业解读
MongoDB | PostgreSQL
Шанхайские Драконы
If you relied on subtle semantics around the meaning of this in non-strict code, you may need to adjust your code as well.