App Server 握手、双向事件与审批：练习答案

练习解答

先按正文生成schema并保存dispatcher.py，同目录保存answer_dispatch.py。运行 python answer_dispatch.py ./schema；导入正文模块先运行其基线测试，再使用全新Host状态检查变体。

from dispatcher import Host,approval
h=Host()
h.receive(approval(21,'int-item'))
h.receive(approval('21','string-item'))
assert h.resolve(21,'decline')=={'id':21,'result':{'decision':'decline'}}
assert ('str','21') in h.pending
assert h.resolve('21','cancel')=={'id':'21','result':{'decision':'cancel'}}
for unknown in (21,999):
    try:h.resolve(unknown,'accept')
    except ValueError:pass
    else:raise AssertionError('unknown or repeated decision')
print('integer and string IDs stay distinct')

JSON-RPC请求身份包含值的类型，整数21与字符串21不能被一个字符串键覆盖。回复保留原id，decline与cancel是安装版schema定义的两种真实决定；它们对turn是否继续的含义不同。