kicad-developers team mailing list archive

[Miguel Angel Ajo Pelayo <miguelangel@xxxxxxx>]

Dick, what we're proposing is not that bad, I mean, it's parameter checking
into C++ functions,
for functions that can cause trouble. This is something good (unless inside
of functions that can cause
high CPU load).

Anyway, other option is to handle this on the scripting side (for every
language), renaming the dangerous
functions to any other thing, and then redefining the function (typechecked
now), but, In my opinion, that
can be worse, as that means that if you increase the enum type one day, you
will have to go to the
renamed function and change the check.

Example:

obj->fn(x)   (x>10 will crash)


so we do

rename obj::fn to obj::_fn

and, in the proper .i file

class obj:
    def fn(x):
         if x>10: throw exception
         else:  self._fn(x)




2012/8/9 Dick Hollenbeck <dick@xxxxxxxxxxx>

> On 08/09/2012 03:33 AM, Miguel Angel Ajo Pelayo wrote:
> > :-P :)
> >
> > /*
> ----------------------------------------------------------------------------
> >  * This file was automatically generated by SWIG (http://www.swig.org).
> >  * Version 2.0.4
> >  *
> >  * This file is not intended to be easily readable and contains a number
> of
> >  * coding conventions designed to improve portability and efficiency. Do
> not make
> >  * changes to this file unless you know what you are doing--modify the
> SWIG
> >  * interface file instead.
> >  *
> -----------------------------------------------------------------------------
> */
> >
> >
> > After the joke,
> >
> >
> > This is one piece of C++ code that checks for PCB_FILE_T parameter of
> LoadBoard
> >
> > WIGINTERN PyObject *_wrap_LoadBoard__SWIG_0(PyObject
> *SWIGUNUSEDPARM(self), PyObject
> > *args) {
> >   PyObject *resultobj = 0;
> >   wxString *arg1 = 0 ;
> >   IO_MGR::PCB_FILE_T arg2 ;
> >   bool temp1 = false ;
> >   int val2 ;
> >   int ecode2 = 0 ;
> >   PyObject * obj0 = 0 ;
> >   PyObject * obj1 = 0 ;
> >   BOARD *result = 0 ;
> >
> >   if (!PyArg_ParseTuple(args,(char *)"OO:LoadBoard",&obj0,&obj1))
> SWIG_fail;
> >   {
> >     arg1 = newWxStringFromPy(obj0);
> >     if (arg1 == NULL) SWIG_fail;
> >     temp1 = true;
> >   }
> >  *ecode2 = SWIG_AsVal_int(obj1, &val2);*
> >   if (!SWIG_IsOK(ecode2)) {
> >     *SWIG_exception_fail(SWIG_ArgError(ecode2), "in method '"
> "LoadBoard" "', argument "
> > "2"" of type '" "IO_MGR::PCB_FILE_T""'");*
> >   }
> >   arg2 = static_cast< IO_MGR::PCB_FILE_T >(val2);
> >   {
> >     try{
> >       result = (BOARD *)LoadBoard(*arg1,arg2);
> >     }
> >     catch( IO_ERROR e )
> >     {
> >       char ExceptionError[256];
> >       sprintf(ExceptionError, "%s\n", TO_UTF8(e.errorText) );
> >       PyErr_SetString(PyExc_IOError,ExceptionError);
> >       return NULL;
> >     }
> >     catch( ... )
> >     {
> >       SWIG_fail;
> >     }
> >
> >
> >
> > As you said, it only checks that it's an "int", and it does an staic
> cast to PCB_FILE_T,
> >
> >
> > It won't be a problem in most situations (where user is dependent from
> the ENUMS to know
> > what he's calling),
> > but for layer numbers, layer colors, etc, it can be a problem, since
> user can start
> > tweaking the parameters, so
> > better do a compare, and throw an exception,
> >
> > if you tell me what kind of exception you can throw, I could set it up
> to convert the
> > exception back to python-land.
> >
> > Do we have some kind of exception for wrong parameters? It could make
> sense now, but not
> > for all situations, only
> > scripting-accesible functions, where enums could be used also as numbers
> (layer number,
> > color number, etc..)
>
>
> Ouch.
>
> Tread carefully.
>
> The value proposition (and acceptance contract on the part of C++
> developers to tolerate
> SWIG) was that all the magic can be done in the SWIG interface files.
>
> If that contract needs to be renegotiated, then lets begin the process of
> renegotiation,
> rather than starting immediately into a breach of contract.    I for one
> want the ugliness
> out of the C++ code.
>
> Warning, warning, warning ...
>
>
>
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-- 

Miguel Angel Ajo Pelayo
http://www.nbee.es
+34 636 52 25 69
skype: ajoajoajo