get_message_paramT_get_message_paramGetMessageParamGetMessageParamget_message_param (算子)

名称

get_message_paramT_get_message_paramGetMessageParamGetMessageParamget_message_param — 查询消息参数或消息相关信息。

签名

描述

get_message_paramget_message_paramGetMessageParamGetMessageParamGetMessageParamget_message_param queries current values of message parameters or other information about the message status.

With each call of get_message_paramget_message_paramGetMessageParamGetMessageParamGetMessageParamget_message_param, only a single parameter value can be queried. However, there are two types of parameters/queries:

• Parameters/queries applicable to the entire message. In this case no keys must be specified, the parameter KeyKeyKeyKeykeykey must be an empty tuple.

• Parameters/queries applicable to the individual keys. In this case a non-empty list of keys must be specified in the parameter KeyKeyKeyKeykeykey. The keys are processed in the same order as specified in the KeyKeyKeyKeykeykey parameter.

Key-independent (global) parameter names:

'message_keys'"message_keys""message_keys""message_keys""message_keys""message_keys"：

Queries all the keys stored in the message, no matter whether they are associated with tuple or object data. The list of keys is reported as a string tuple via GenParamValueGenParamValueGenParamValueGenParamValuegenParamValuegen_param_value. For this query the parameter KeyKeyKeyKeykeykey must be an empty tuple.

Currently supported key-specific parameter names are:

'key_exists'"key_exists""key_exists""key_exists""key_exists""key_exists"：

Reports 1 if the given key is stored in the message, 0 otherwise. The results are reported via GenParamValueGenParamValueGenParamValueGenParamValuegenParamValuegen_param_value, one value for each key.

'key_data_type'"key_data_type""key_data_type""key_data_type""key_data_type""key_data_type"：

Reports 'tuple'"tuple""tuple""tuple""tuple""tuple" for keys associated with tuple data within the message (the data can be retrieved using get_message_tupleget_message_tupleGetMessageTupleGetMessageTupleGetMessageTupleget_message_tuple). Reports 'object'"object""object""object""object""object" for keys associated with object data (the data can be retrieved using get_message_objget_message_objGetMessageObjGetMessageObjGetMessageObjget_message_obj). The results are reported via GenParamValueGenParamValueGenParamValueGenParamValuegenParamValuegen_param_value, one value for each key. This parameter is useful to decide dynamically whether to use get_message_tupleget_message_tupleGetMessageTupleGetMessageTupleGetMessageTupleget_message_tuple or get_message_objget_message_objGetMessageObjGetMessageObjGetMessageObjget_message_obj to get the data of a specific key.

执行信息

• 多线程类型：可重入（与非独占算子并行运行）。
• 多线程作用域：全局（可从任何线程调用）。
• 未采用并行化处理。

参数

示例（HDevelop）

get_message_param (Message, 'message_keys', [], AllKeys)
get_message_param (Message, 'key_data_type', AllKeys, KeysType)

结果

If all the operator parameters, and the specified keys are valid, get_message_paramget_message_paramGetMessageParamGetMessageParamGetMessageParamget_message_param 返回 2 ( H_MSG_TRUE )。否则将抛出异常。

可能的前趋

dequeue_messagedequeue_messageDequeueMessageDequeueMessageDequeueMessagedequeue_message

另见

create_messagecreate_messageCreateMessageCreateMessageCreateMessagecreate_message, clear_messageclear_messageClearMessageClearMessageClearMessageclear_message, set_message_tupleset_message_tupleSetMessageTupleSetMessageTupleSetMessageTupleset_message_tuple, get_message_tupleget_message_tupleGetMessageTupleGetMessageTupleGetMessageTupleget_message_tuple, set_message_objset_message_objSetMessageObjSetMessageObjSetMessageObjset_message_obj, get_message_objget_message_objGetMessageObjGetMessageObjGetMessageObjget_message_obj, set_message_paramset_message_paramSetMessageParamSetMessageParamSetMessageParamset_message_param, enqueue_messageenqueue_messageEnqueueMessageEnqueueMessageEnqueueMessageenqueue_message, dequeue_messagedequeue_messageDequeueMessageDequeueMessageDequeueMessagedequeue_message

模块

基础