Re: Break as valid logical expression

[Pascal A. Dupuis]

On Wed, 13 Nov 2002, John W. Eaton wrote:

> | quite frankly, I don't understand what would mean a "x=break" statement.
>
> Neither do I, which is why I was asking whether these expressions
> (break, continue, return) should be limited to only && and ||
> expressions).
The purpose is to emulate sh and Perl behaviour:
1) evaluate the left part of the logical expression
2) if the result permit to know the final result, then done
3) otherwise, evaluate the right part.

So:
test || break: break only occur if test if false. If it's true, then the
final result is true
test && break: break only occur if test is true. If it's false, then the
final result is false


> I don't know how to limit that given the current implementation of
> Octave's interpreter.  As things are now, break, continue, and return
> simply set a global flag which is inspected by the interpreter when
> the next expression is evaluated.  In order to be valid in any
> expression context (even if limited to && and || expressions), they
> must return some value.
>
I would suggest having them 'return' some value, but which is
illegal to assign to any variable, so
test || break;
is OK, while
x=(test || break) is not

Regards

Pascal Dupuis

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