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<== Date ==> <== Thread ==>
Subject: Re: double filters
From: Ralph Lange via Core-talk <core-talk at aps.anl.gov>
To: EPICS Core Talk <core-talk at aps.anl.gov>
Date: Mon, 30 Mar 2020 09:49:02 +0200
On Mon, 30 Mar 2020 at 06:08, Johnson, Andrew N. via Core-talk <core-talk at aps.anl.gov> wrote:
I gets worse though. If we add put/write filters to the picture, then
the feature is no longer "no cost". In fact, supporting it is not
possible without a lot of overhead.

I agree that put filters are probably completely different to get/monitor filters, and there will probably be only a few put filters.

The longer I think about it, the more I think that "put filters" should indeed be something completely separate. Maybe the put variant should not be called "filter" in the first place, but... "operator"? "manipulator"?
The data is different. (Mostly no meta data, no timestamp, no "from the record" type.) The operation is different (as seen in the array case). There are no pre-queue / post-queue considerations. Many very reasonable filters have no equivalent put-thing.

Filters and put-things could share configuration and instantiation mechanism, maybe in a separate namespace - to e.g. allow "arr" and the "[]" to point to the filter and the put-thing.
Limitations and restrictions could easily apply to one direction only. (Chained array filters are ok, chained array put-things are not.)

I think such an approach could simplify the implementation.

Cheers,
~Ralph
Replies:
Re: double filters Ben Franksen via Core-talk
Re: double filters Ben Franksen via Core-talk
References:
double filters Ben Franksen via Core-talk
Re: double filters Johnson, Andrew N. via Core-talk
Re: double filters Ben Franksen via Core-talk
Re: double filters Johnson, Andrew N. via Core-talk
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