Block conditional expressions (was: Scoping of variables in block constructs)

[Achim G. <Str...@ne...>]

Achim Gratz writes:
> Ethan A Merritt via gnuplot-beta writes:
>>> Also, why is there no block "else if" or maybe even "elsif"?
>>
>> No particular reason.  
>> So far as I can see, all it would gain is to reduce the number of 
>> required curly brackets by one pair.
>> Is there something more subtle I'm missing?
>
> Maybe.  If the conditional expressions themselve need to be nested, you
> will either end up with unwieldy formatting
>
> if (…) {
> else {
>   if (…) {
>   else {
>    if (…) {
>    else {
>     if (…) {
>     else {
>       if (…) {
>       else {
>         if (…) {
>
> or you'll need to explicitly repeat (and revert) the logical expression
> from the former branches.


Example for that latter point:

--8<---------------cut here---------------start------------->8---
if (days <= 1/24.) {
  set xtics  15/60.
  set mxtics 3
}
if (days > 1/24. && days <= 4/24.) {
  set xtics  1
  set mxtics 12
}
if (days > 4/24. && days <= 2) {
  set xtics  1
  set mxtics 4
}
if (days > 12/24. && days <= 2) {
  set xtics  2
  set mxtics 8
}
if (days > 2 && days <= 6) {
  set xtics  6
  set mxtics 12
}
if (days > 6 && days <= 13) {
  set xtics  12
  set mxtics 12
}
if (days > 13 && days <= 27) {
  set xtics  24
  set mxtics 8
}
if (days > 27 && days <= 41) {
  set xtics  24
  set mxtics 4
}
if (days > 41) {
  set xtics  7*24
  set mxtics 14
}
--8<---------------cut here---------------end--------------->8---

So with that hypothetical elsif keyword, things would look a lot saner
and be less error-prone, I think:

--8<---------------cut here---------------start------------->8---
if (days <= 1/24.) {
  set xtics  15/60.
  set mxtics 3
} elsif (days <= 4/24.) {
  set xtics  1
  set mxtics 12
} elsif (days <= 2) {
  set xtics  1
  set mxtics 4
} elsif (days <= 2) {
  set xtics  2
  set mxtics 8
} elsif (days <= 6) {
  set xtics  6
  set mxtics 12
} elsif (days <= 13) {
  set xtics  12
  set mxtics 12
} elsif (days <= 27) {
  set xtics  24
  set mxtics 8
} elsif (days <= 41) {
  set xtics  24
  set mxtics 4
} else {
  set xtics  7*24
  set mxtics 14
}
--8<---------------cut here---------------end--------------->8---


Achim.
-- 
+<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+

Wavetables for the Waldorf Blofeld:
http://Synth.Stromeko.net/Downloads.html#BlofeldUserWavetables