[ros-users] [Discourse.ros.org] Suggestions for std_srvs

Georg Heppner ros.discourse at gmail.com
Wed Jan 11 22:14:49 UTC 2017

@tfoote you make compelling arguments ;)

In general I am convinced by the logic of having it semantically sound and using exchange formats in a well defined manner, but on the other hand I also agree with @fmauch. When we treat services as function calls (or somewhat remote procedure calls), why do we treat types different than in such a function call?

In Particular, @wjwwood, what exactly would be the abuse of using a SetFloat32 fot /set_desired_temp? That no unit is given? Or that you could give values that are excedingly large or something like that? I think I would use a simple float as parameter for this if implemented as method. Thats why there are return values :)

Aggain, for any more complex data type, where I would use a struct or class, I agree, custom services are the thing to use. But for simple data types? Where is the harm in someone inputting something semantically differnt in the service call if it is syntactically correct?  Thats why I asked about if it really should be the task of the type definition to handle this. Because if i wanted to, I could also write some weird stuff into custom defined types. For example an image could very well be wrongly encoded or contain weird depth data. When something is offering to accept floats, the input type is also quite well defined as beeing a float.

By the way, thanks everone for this discussion, we had simmilar discussions offline, so getting the insigths and design views of everybody is quite helpfull.

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