[Scilab-Dev] SEP #40: Cell Arrays

[Samuel Gougeon]

Hello,

Le 18/02/2016 20:41, Eric Dubois a écrit :
> Hello
>
> I am inclined to share Samuel point of view: this is a compliocation 
> than could be avoided.
>
> But I cannot resist noting that the annoucement is 6 years older than 
> the announcement of the weapon of mass destruction that consist in 
> changing the behaviour of the addition of a matrix with a null matrix.
>
> Sorry for insisting, but I will again call for the removal from the 
> final Scilab 6.0 release of this planned change.
>
> First, I am not convinced at all by the argument put forward that it 
> will make Scilab more consistent with other language such as Matlab, 
> Octave, Julia.. : after all, every language has its indiosycrasies; a 
> Matlab user will yet have to adapt herslef to this change, bu along 
> many other ones; and I,do not think that changing this behavour will 
> convice any Matlab user to switch to Scilab nor prevent anyone 
> thinking about switching to give up because of this beahviour.
>
> Second The argument that it enhances Scilab internal consistency is a 
> little bit more compelling, but not much: after all, addition and 
> subtraction are different operations from multiplication and division, 
> such one can justify different behaviour. And there are cases when it 
> make tho code more compact.
>
> Adnd lastly both arguments are anyway swept away by the simple fact 
> that the change should make all previous code unreliable: you cannot 
> be sure in advance that the working of your program has not been 
> affected by the change (and the warning that is designed to alert to 
> the user is not sufficient: a warning can easily be missed, especially 
> for second hand users not so famaliar with Scilab and if it is hidden 
> among many other warnings).

I have the same feeling, and i agree mostly with your last remark. We 
could stress on some "pitfalls" set by the oldEmptyBehaviour flag or by 
the "warning stop" behavior:

  * oldEmptyBehaviour flag:We may guess that this flag is a /global/
    one. Isn't it? So, if we set it at the beginning of a script or of a
    macro, then it applies to the whole Scilab session (i haven't
    checked that), even after leaving the script or the macro. If so,
    then if in a session we process some recent up-to-date scripts or
    macros, and some other ones that are not up-to-date, what will
    occur, whatever is the flag's value? This is not really clear.

  * warning("stop"): i agree that, in order to update all contents and
    to be sure that results are reliable and not polluted by
    unpredictable "[]+-" side effects, this warning mode will have to be
    always activated for a very long period, may be up to Scilab 7.
    Then, the problem is that this stopping mode does not resolve the
    cause: if an up-to-date package intentionally uses warnings for
    anything else than []+, it will be stopped as well.
    This warning mode should accept an additional parameter identifying
    the type of event (or a series/vector of events) for which stopping
    must occur. Shouln't it?

BR
Samuel

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