Comment 4 for bug 1935037

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Niko Kivel (niko-kivel) wrote : Re: [Bug 1935037] Re: Invalid charactor in field name

If this limitation stays like that, it's a complete show-stopper for me.
I'd like to create structures for EtherCAT terminal/slave data. There are
potentially hundreds of PVs to add to pva-groups. All based on their PV
names. Since the PV names have to adhere to the naming convention, they
have '-' between entity name and suffix, i.e. BI02-TimeRise,
master7-Online, BO03-Array, ...
I'd be perfectly happy with a replacement mechanism. I.e. upon adding a PV
to the group, replace non-supported characters with '_'.
Maybe with a flag to prevent automatic conversion? And cause the Error to
be thrown?

On Thu, Aug 26, 2021 at 6:25 PM mdavidsaver <email address hidden>

> The character set restriction of PVD fields (in groups or otherwise) is
> meant to mirror that of C89 keywords.
> > int abc;
> ... is valid
> > int a-bc;
> ... is not
> This was a somewhat arbitrary decision made many years ago. imo.
> changing it is primarily a question of backwards compatibility.
> Anything rejected by (or crashing) existing/older clients is a non-
> starter.
> Be aware that there is no separate versioning for the PVD encoding.
> imo. an oversight in the design. The negotiated PVA protocol version is
> the only way to communicate handle changes. You should also be aware
> that the existing pvData (de)serialization APIs don't expose the
> negotiated protocol version. So making even seemingly small changes to
> the PVD encoding format would be complicated.
> --
> You received this bug notification because you are subscribed to the bug
> report.
> Title:
> Invalid charactor in field name
> Status in EPICS Base:
> New
> Bug description:
> When creating a group in QSRV, the allowed characters are too
> restrictive
> error:
> Error Group not created: Invalid charactor '-' (45) in field name
> "BI02-TimeRise" must be A-Z, a-z, 0-9, or '_'
> expected behaviour:
> pva structures should allow for a more liberal set of characters that
> just what is covered by \w regex metacharacter.
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