Re: parsing of if else command

[Juergen W. <wie...@fr...>]

Am Dienstag, 8. April 2008 schrieb Ethan A Merritt:
> On Monday 07 April 2008 15:13, Tim Hoffmann wrote:
> > Hello,
> >
> > because of a recent discussion on comp.graphics.apps.gnuplot I realized
> > that the parsing of if ... else ... is somewhat "unusual". If the
> > condition fails, gnuplot will jump to the next else (as documented). I
> > don't consider this to be a good solution, because this causes troubles
> > in nested if else statements.
>
> I think the biggest problem with gnuplot's if/else implementation is
> that it is limited to a single line.  The following simple construct,
> if it were possible, would make the whole thing a lot more usable:
>    if (test) load 'option1'; else load 'option2';
> The files 'option1' and 'option2' could hold arbitrarily complex
> code, partially making up for the lack of block structure.
> But this doesn't work, because the command 'load' destroys the rest of
> the line.  Since an 'else' clase must be on the same line, but the
> line is lost, you can have no 'else' clause after a 'load' command.
>
> So I suggest that the first step should be extending the syntax to
> allow multi-line constructs.  Here is one possibility:
>
> if (test) begin
>    ...
>    ...
> else begin
>    ...
>    ...
> endif
>
>
> The 'begin' and 'endif' are not needed if the command remains on a single
> line, so backwards compatibility is maintained.

Sounds good.  One line nested ifs should then be depricated.  As
soon as there are blocks, can in-file loops also be implemented?

Juergen