Re: gnuplot-4.4.0-rc1 breaks gnuplot script

[Hans-Bernhard B. <HBB...@t-...>]

Teo S Bernhard wrote:

> Your suggestion breaks  gridding/zooming/... capability in the plot.
> This happens because the a-variable is not initiated within the plot statement.
> I find when trying:    a=0; plot [0:1] a*x, a=a+1, a*x
> - while toggling the grid  I see that the first plot shows '1x' and
> 2x, while the second version shows: '3x' and '4x'.

So initialize it inside.  That still doesn't constitute a need to do 
something after the last of the data sets.

> The sole issue of mine is that gnuplot version 4.4 rc1 breaks backward
> compatibility 

No, it doesn't.  It's not an issue of compatibility if something that 
was never promised to work, stops to.

> below - that it is gnuplot 4.4.0 rc1 that is at odds with the
> documentation.

I disagree with that claim.  It was the earlier versions that were at 
odds with the documentation, by allowing things that the documentation 
said they didn't.

>   c) In the briefer usage instruction (repeated below) I notice the
> optional trailing comma after definitions {,},  I also notice the
> replaceable <function>.

And that means that a function (or datafile), _has_ to be there.  If 
it's not, that's disallowed by the syntax of the command.

>   Considering the interpretation of item c), practical experience with
> gnuplot versions 4.3, 4.2, 4.0,...,  suggest that there is no need for
> a trailing comma after a  definition if there is no trailing
> <function>, here <function> can be replaced by nothing. In my opinion,
> the latter is a reasonable interpretation which is supported by
> historic gnuplot implementations. See the brief usage instruction:
>      plot {<ranges>}
>              {<iteration>}
>              {<function> | {"<datafile>" {datafile-modifiers}}}
>              {axes <axes>} {<title-spec>} {with <style>}
>              {, {definitions{,}} <function> ...}

Well, since you want to base claims on history, let's step back just one 
release from 4.4-rc1, to 4.2pl5:

Syntax:
       plot {<ranges>}
            {<function> | {"<datafile>" {datafile-modifiers}}}
            {axes <axes>} {<title-spec>} {with <style>}
            {, {definitions,} <function> ...}

Note how that rather explicitly used to _require_ a comma after every 
definition, thereby forbidding what you were doing.  The only bug to be 
fixed here is in the old versions not flagging this usage error.