Experimental Physics and
Industrial Control System

Am 14.03.20 um 00:05 schrieb Johnson, Andrew N. via Tech-talk:
> However as Ralph said there isn’t a way for a filter to
> modify data that is being written to the IOC yet, so far we only have
> methods for filtering on reads (similar paths are used for both Get
> and Monitor operations).
>
> Hope this is enough to get you started.

Apparently not.

I have been looking at this for a few hours now and still don't have the
slightest clue where to start. I guess one of the reasons I am having
such problems is that access via link now goes through interfaces (a
struct of functions, lset in this case) which makes it extremely hard to
find out how things fit together. For instance, I see that lset has a
method getValue. But when I grep for "getValue" I only get the call
sites, but not the places that /set/ the getValue method. Because the
interfaces are constructed using C initializers which don't mention the
method names i.e. the names of the struct members. So there is no easy
way to find out how a typical method implementation looks like. This is
the same problem I have every time I try to understand OO code of any
sort. I wonder how others perceive this.

Strangely, I didn't seem to have this difficulty with record and device
supports. Perhaps this is because all record and device supports in base
live in their own directory (modules/database/src/stdto /{dev,rec}).
There are some lset definitions under modules/database/src/std/link. It
looks as if lnkState.c has some relation to JSON links but I haven't
found out how exactly it is related.

Cheers
Ben

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Attachment: pEpkey.asc
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References:

write to a single element of an array field Benjamin Franksen via Tech-talk

Re: write to a single element of an array field Ralph Lange via Tech-talk

Re: write to a single element of an array field Ben Franksen via Tech-talk

Re: write to a single element of an array field Johnson, Andrew N. via Tech-talk

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