[Scilab-users] Emulate Object Oriented Programming
michael.baudin at contrib.scilab.org
michael.baudin at contrib.scilab.org
Thu Nov 29 09:26:15 CET 2012
Hi,
Thanks for the input.
I did not know this syntax, but it really works !
-->[NONE, CONTINUOUS, DISCRETE, FFT] = (1, 2, 3, 4)
FFT =
4.
DISCRETE =
3.
CONTINUOUS =
2.
NONE =
1.
This sounds weird, since the "(1, 2, 3, 4)" variable has no meaning
by itself:
-->(1, 2, 3, 4)
!--error 41
Incompatible output argument.
Anyway, with respect to the current topic, this method would require
to define these 4 variables (ie NONE, CONTINUOUS, DISCRETE, FFT) in
all the functions which access to the fields.
This could be done "manually", by pasting this statement (which is far
from being perfect), or by defining a global variable (which is far
from
being perfect).
These problems do not occur in the usual case where we have a single
function which uses these indices.
I'd rather try Serge's method (the one based on the %name field names).
I'll share the updated code when I can.
Best regards,
Michaël
Le 2012-11-27 11:10, Mike Page a écrit :
> You could of course "define constants" in Scilab. This is what I
> usually do:
>
> [NONE, CONTINUOUS, DISCRETE, FFT] = (1, 2, 3, 4);
>
> OK - not perfect, but it makes code more readable.
>
> HTH,
> Mike.
>
>
> -----Original Message-----
> From: users-bounces at lists.scilab.org
> [mailto:users-bounces at lists.scilab.org]On Behalf Of
> michael.baudin at contrib.scilab.org
> Sent: 27 November 2012 09:08
> To: users at lists.scilab.org
> Subject: Re: [Scilab-users] Emulate Object Oriented Programming
>
>
> Hi,
>
> Thank you Serge for this interesting script.
> Defining a tlist with unnamed fields is indeed an idea which
> is quite unusual !
>
> You will find in attachment a modified version, merging your proposal
> and my
> previous attempt.
>
> On the user's side, the "object" can now produce messages such as:
>
> -->bob.weight=-5
> !--error 10000
> Expect nonnegative weight.
> at line 18 of function %s_i_THUMAN called by :
> bob.weight=-5
>
> which is excellent.
>
> On the developper's side, the "set" function (which is
> called insertion in the overloading vocabulary), is now
> much less clear, because fields are now identified with
> their index (i.e. 1, 2, 3,...) instead of their name
> (i.e. "name", "weight", ...).
>
> For example, this is the code to set the "weight" field:
>
> function h=%s_i_THUMAN(field,value,h)
> [...]
> select field
> case "weight"
> [...]
> if (value<0) then
> error("Expect nonnegative weight.")
> end
> h(4)=value
> [...]
>
> So this is not an ideal solution: it has some advantages for the
> users, but is much more difficult for the developper.
> It is a huge source of bugs, for example if we mix up the
> indices: e.g. 2 instead of 4 will set the "name" instead of the
> "weight".
> In the C language, we would #define constants to these indices,
> so that we can avoid this problem.
> But this is Scilab, not C.
>
> Isn't there a simpler way ?
> In other words, couldn't we get the named fields both from the
> user's and the developper's sides ?
>
> Best regards,
>
> Michaël
>
> Le 2012-11-26 19:09, Serge Steer a écrit :
>> For safe mode you can use tlist with no field names. See the example
>> in the attached file
>>
>> Serge Steer
>>
>> -------------------------
>>
>>> DE: "Daniel Penalva" <dkajah at gmail.com>
>>> À: "International users mailing list for Scilab."
>>> <users at lists.scilab.org>
>>> ENVOYÉ: Dimanche 25 Novembre 2012 23:04:56
>>> OBJET: Re: [Scilab-users] Emulate Object Oriented Programming
>>>
>>> Hi,
>>>
>>> By safe you mean that the field is protected or private ? i dont
>>> know if it is possible in scilab nowadays ...
>>>
>>> [ ]s
>>>
>>> On Sun, Nov 25, 2012 at 7:28 PM,
>>> <michael.baudin at contrib.scilab.org>
>>> wrote:
>>>
>>>> Hi,
>>>>
>>>> I have a problem with the possibility of emulating OOP in Scilab
>>>> with
>>>> tlists, that prevents me to have safe "set" methods.
>>>> In the script in attachment, I created a human "class" with
>>>> two fields: name (a scalar string) and weight (a scalar real).
>>>>
>>>> The problem is : how have a "set" method which is both simple and
>>>> safe ?
>>>>
>>>> Here is how this class works :
>>>>
>>>> bob=human_new()
>>>>
>>>> This is simple, but is unsafe:
>>>>
>>>> bob.name [1]="Bob"
>>>> bob.weight=70
>>>> bob.name [1]=-12 // Oups !
>>>>
>>>> These statements are safe:
>>>>
>>>> bob=human_set(bob,"name","Will")
>>>> bob=human_set(bob,"weight",80)
>>>>
>>>> It is safe in the sense that the following statements produce an
>>>> error:
>>>>
>>>> bob=human_set(bob,"weight",-12)
>>>>
>>>> The function "human_set" is safe but somewhat unconvenient to use.
>>>>
>>>> The question is :
>>>>
>>>> How to make so that bob.name [1]="Will" makes the code
>>>> bob=human_set(bob,"name","Will") be executed ? Can overloading do
>>>> this ?
>>>>
>>>> Is the only possible way is at the C level with the sci_percent*
>>>> functions that Denizet wrote :
>>>>
>>>>
>>>>
>>>> http://gitweb.scilab.org/?p=scilab.git;a=blob;f=scilab/modules/xml/sci_gateway/cpp/sci_percent_XMLAttr_size.cpp;h=9d3b361bcbe6416e62f422dd448aa72d65f1fe4c;hb=HEAD
>>>> [2]
>>>>
>>>> for the XML module ?
>>>>
>>>> Best regards,
>>>>
>>>> Michaël
>>>>
>>>> _______________________________________________
>>>> users mailing list
>>>> users at lists.scilab.org
>>>> http://lists.scilab.org/mailman/listinfo/users [3]
>>>
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>>
>>
>>
>> Links:
>> ------
>> [1] http://bob.name
>> [2]
>>
>>
>> http://gitweb.scilab.org/?p=scilab.git;a=blob;f=scilab/modules/xml/sci_gateway/cpp/sci_percent_XMLAttr_size.cpp;h=9d3b361bcbe6416e62f422dd448aa72d65f1fe4c;hb=HEAD
>> [3] http://lists.scilab.org/mailman/listinfo/users
>> [4] http://li7e.org/ddd2
>> [5]
>>
>>
>> http://rede.metareciclagem.org/blog/16-10-12/Des-Carta-da-Rede-Metareciclagem-para-o-Ministerio-da-Cultura-e-Outros-Ministerios-Tam
>> [6] http://afroambiental.org
>> [7] http://www.ift.unesp.br/posgrad/ramais-alunos-pos.php
>> [8] http://www.nightsc.com.br/aa/interface_v0.1.php
>>
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