Re: Late evaluation (was: Re: [ gnuplot-Patches-992149 ] String ...)

[Hans-Bernhard B. <br...@ph...>]

On Thu, 22 Jul 2004, Volker Dobler wrote:

> Hans-Bernhard Broeker <br...@ph...> schrieb am 22.07.04 04:08:18:
> > 
> > gnuplot> set arrow 1 from x, y to x, a(0)
> > gnuplot> show arrow
> > 
> > arrow 1, linetype 1, linewidth 1.000 nofilled back
> > from (2, 1, 0) to (2, 2, 0)
> > 
> > In the light of this, I hope you can see how the only part about your
> > proposal I really don't agree with is the fact that it introduces late
> > evaluation only for strings. I do agree that late evaluation is a useful
> > tool to add. But I disagree about it being useful for strings _only_.
> > 
> 
> That's a clear example why I think "late evaluation" as proposed is
> a bad idea for the users:  Labels might change their text, but stay
> at the same location, even if text and location "depend" on the
> same variable:

You didn't read my post close enough, it seems.  You, like I originally
did, assume late evaluation will *always* be done --- but that's not the
case.  Late evaluation will be a separate feature which has nothing in
particular to do with string expressions.

> From my personal usage of gnuplot, I have to admit, that I do 
> not see, why something like
>   
> gnuplot> f(x) = sprintf("%7.5f",x)
> 
> is necesseary.  What problem can be solved by this user-defined
> function which cannot (or at least not eaily) be solved by other
> means?

The same kind that most users currently solve by defining functions
like

	f(x) = a*x**2 + b*x + c

when they ocould just as well re-type that expression every time they will
now write f(x):  it saves typing and makes it easier to model final
commands by some textbook or internal representation the user is working
with.

-- 
Hans-Bernhard Broeker (br...@ph...)
Even if all the snow were burnt, ashes would remain.