On 01/03/2021 09:06, Stéphane Mottelet wrote:
Hi Frederico,
I do not have any problem with the variable scoping in Scilab and as I
said before, even in Julia there is a similar scoping (at least for
the particular case of functions). However, the status of formal input
and output parameters should prevent the scoping to apply to them. For
example, the following does also work (as an addition to my previous
example for the input parameter):
function y=f(x)
endfunction
y=1
f
-> f
ans =
1.
Frankly speaking, allowing such a behavior is madness...
Hello Stéphane,
Yes, I think both behaviors you described are non intuitive.
Antoine
S.
Le 27/02/2021 à 01:33, Federico Miyara a écrit :
Stéphane,
I agree it shouldn't happen, but the same moment access to outer
variables is granted you can't prevent such thing to happen since
inside the function all variables have a name which is more than just
a symbol or a mute variable, and this includes undefined arguments.
This scoping feature is dangerous and I don't think it would be
advisable to create a macro for general use exploiting it.
May be someone can provide an example where it has been used with
profit or explain why it was originally introduced
Regards,
Federico Miyara
On 26/02/2021 10:38, Stéphane Mottelet wrote:
Hi all,
In Scilab the scope of variables is quite permissive but even in
Julia (really strict rules) we can have the following behavior:
function y=f(x)
y=x+a;
end
a=1;
f(2)
a=2;
f(3)
-> a=1;
--> f(2)
ans =
3.
--> a=2;
--> f(3)
ans =
5.
Yesterday afternoon I was my students for a Scilab beginners
tutorial, and by accident one of them had "x" defined before in the
main workspace and tried to call f without arguments. I reproduce
the experiment here by explicitely defining x before the call:
x=1;
f
--> x=1;
--> f
ans =
3.
Allowing the function inner scope to see variables of the outer
scope is one thing, you may or may not agree this is not the point
here, but allowing to call f without arguments just because the
formal input parameter has the same symbol as an outer scope symbol
is another thing. I knew this was possible even if i never used such
a feature, but my students were so puzzled by this, particularly
those who already learned other low-level languages, that I decided
to propose the suppression of this, that I consider as a serious
potential source of many bugs. Don't tell me that this would break
some user code because I frankly have no consideration for this kind
of crappy shortcut and, sorry if it may sound rude, for programmers
who use it...
S.
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--
Stéphane Mottelet
Ingénieur de recherche
EA 4297 Transformations Intégrées de la Matière Renouvelable
Département Génie des Procédés Industriels
Sorbonne Universités - Université de Technologie de Compiègne
CS 60319, 60203 Compiègne cedex
Tel : +33(0)344234688
http://www.utc.fr/~mottelet
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