Don’t know if you followed that discussion on LinkedIn, where I asked about the
array notation.
Turned out that you can generally do all sorts of crazy stuff … such as define
Arrays that start at 6 and go to 12 … in general you can let your first element
be whatever you like.
I guess if we interpret just one number as array size and if the array is
defined as [6..12] and I read a [3], then it should probably return the
elements 6,7,8 … but if I do a [0..3] it should probably fail and if I do
[7..10] then it should return 7, 8, 9 and 10.
Would that interpretation make more sense? Then on PLCs where the first element
has the index 1 I can continue to use the same semantics as in one where 0 is
the default. However the user would have to know which is the first index when
using the X..Y notation.
Chris
From: Christofer Dutz <christofer.d...@c-ware.de>
Date: Saturday, 29. October 2022 at 20:15
To: dev@plc4x.apache.org <dev@plc4x.apache.org>
Subject: Re: Change the array-notation in fields?
Hi Ben,
in general we currently have no option to read partial arrays starting with
anything else than the first element.
That’s generally what I’m currently trying to add.
Chris
From: Ben Hutcheson <ben.hut...@gmail.com>
Date: Saturday, 29. October 2022 at 18:35
To: dev@plc4x.apache.org <dev@plc4x.apache.org>
Subject: Re: Change the array-notation in fields?
As long as the original notation is kept, Im sure no one will mind.
Changing the wording in the original from numElements to endIndex seems to
have very little effect except to force the user to think about the start
index as starting at 1.
In practise do we have the ability to read partial arrays in any of the
drivers?
On Sat, 29 Oct 2022 at 9:35 am, Lukas Ott <ott.lukas...@gmail.com> wrote:
> The question for me is why not startIndex = 0
> Instead of 1.
>
> In general this proposal sound reasonable to me and a I opt +1.
> Luk
>
> Am Sa., 29. Okt. 2022 um 17:30 Uhr schrieb Christofer Dutz <
> christofer.d...@c-ware.de>:
>
> > Hi all
> >
> > currently in most drivers we support an array notation like:
> > XYZ{numElements}]
> > In order to support reading arrays.
> >
> > Now in order to support reading partial arrays, I think it would be good
> > to generally change that to:
> >
> > XYZ[{startIndex}..{endIndex}]
> >
> > And the ordinary version:
> >
> > XYZ[{endIndex}]
> >
> > This would imply starting at the first element.
> > However, we should probably start with index “1”, as this seems to be
> what
> > most seem to use.
> >
> > So:
> > XYZ
> > Would be the same as:
> > XYZ[1]
> > Would be the same as:
> > XYZ[1..1]
> >
> > What do you think?
> >
> > Chris
> >
>
