Experimental Physics and
Industrial Control System

Keenan Lang via Core-talk <[email protected]> · Tue, 04 Jun 2019 10:31:21 -0000

>I'm regretting the exposure of iocshCmdDef::func and allowing outside code to directly call iocsh functions. In retrospect, we should have insisted on having a wrapper function such as is being discussed now.

It is unlikely that any wrapper decided on back then would have a return type, so there would still not be a way to expose error/exception data to outside code and a new wrapper function would likely be necessary.

>True, this is either "defensive programming", or laziness. Easier to test for NULL than decide if it is impossible.

If there is a movement to add explicit preconditions to the functions in core, I'd absolutely support and help with that. Without those, it's not really laziness, it's ensuring that the code functions as advertised.

>Maybe the question is whether you are motivated to work on this yourself?

As we talked about offline, I'll just end up removing my reliance on iocshFindCommand and you can remove that part of the API. However, I would also be absolutely willing to rewrite that part of the code as well. It is only the way it is because I was attempting to change as little as possible.

>And I suppose we are all dancing around the question of if/when to rewrite iocsh.cpp (as actual c++), or replace it with (something like) a lua interpreter shell.

As far as I have gathered, the ioc shell is supposed to match up with the vxWorks shell as reasonably as possible. This (as well as conservation of developer effort) was the reason why anything even slightly advanced like exceptions, conditionals, or arithmetic have been, so-far, excluded from iocsh. This level of very basic exception support doesn't end up reaching a major breaking point in compatibility between the iocsh and the vxWorks shell, but it's definitely getting close to that line.
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System