[AMPL 1831] Re: Seemingly incorrect behavior: AMPL if block evaluation

> David,
>
> "include" takes a copy of the specified file and makes it a part of the
> current file, regardless of any surrounding conditional statements.  (It's
> like a "macro" in programming languages.)
>
> To get the effect you want, write
>
>     if (time >= 2) then {
>         commands process.run;
>     }
>
> "commands" is an ordinary command that causes all of the statements in the
> specified file to be executed, and then returns control to the current file.
>
> Bob Fourer
> 4...@...
>
> > -----Original Message-----
> > From: ampl@... [mailto:ampl@...] On Behalf Of
> > David Veerasingam
> > Sent: Thursday, June 12, 2008 2:40 PM
> > To: AMPL Modeling Language
> > Subject: [AMPL 1826] Seemingly incorrect behavior: AMPL if block
> > evaluation
>
> > Hello all,
>
> > It seems to me that AMPL is evaluating `if' blocks even when the
> > condition is false.
>
> > Example:
> > 1) I have an `if' block that looks like this
>
> >     if (time >= 2) then {
> >         include process.run;
> >     }
>
> > 2) However, I've found that even when time = 0, the block still
> > executes and AMPL quits on this error:
>
> >         Can't find  file "process.run"
> > context:  include  >>> process.run; <<<
>
> > Well, the process.run file isn't generated at the conditions time = 0
> > or time = 1. The `if' statement is supposed to prevent that block from
> > executing.
>
> > Therefore my question is: How can I force AMPL to avoid throwing an
> > error?
>
> > Thanks for your help!
>
> > David