pygccxml-development

[pygccxml-development] char *variables

[Gordon W. <gor...@gm...>]

I have my char *variables working now, here's the current py++ code I am
using, any comments would be appreciated

for (className, varName) in stringVars:
    wrapClass = mb.class_(className)
    wrapClass.var(varName).exclude()
    wrapAlias = wrapClass.wrapper_alias

    wrapperCode = """
        char *wrap_%s;
        void set_%s(%s& inst, bp::object obj){
            char **strPtr = &wrap_%s;
            if(*strPtr != NULL) delete *strPtr;
            bp::extract<std::string> x(obj);
            if (x.check()){
                std::string str = x();
                *strPtr = new char[str.length()+1];
                strcpy_s(*strPtr, str.length()+1, str.c_str());
            }else{
                *strPtr = NULL;
            }
            inst.%s = *strPtr;
        }
        static boost::python::object get_%s(%s& inst){
            std::string str;
            if(inst.%s != NULL){
                std::string str(inst.%s);
                return bp::object(str);
            }else{
                return bp::object();
            }
        }
        """ % (varName, varName, className, varName, varName, varName,
className, varName, varName)
    wrapClass.add_wrapper_code(wrapperCode)

    constructorCode = "wrap_%s = NULL;" % (varName)
    add_constructors_body(wrapClass, constructorCode)

    registrationCode = 'add_property("%s", &%s::get_%s, &%s::set_%s)' %
(varName, wrapAlias, varName, wrapAlias, varName)
    wrapClass.add_registration_code(registrationCode)

Re: [pygccxml-development] char *variables

[Roman Y. <rom...@gm...>]

On Fri, Jul 11, 2008 at 6:51 AM, Gordon Wrigley
<gor...@gm...> wrote:
> I have my char *variables working now, here's the current py++ code I am
> using, any comments would be appreciated
>
> for (className, varName) in stringVars:
>     wrapClass = mb.class_(className)
>     wrapClass.var(varName).exclude()
>     wrapAlias = wrapClass.wrapper_alias
>
>     wrapperCode = """
>         char *wrap_%s;
>         void set_%s(%s& inst, bp::object obj){
>             char **strPtr = &wrap_%s;
>             if(*strPtr != NULL) delete *strPtr;
>             bp::extract<std::string> x(obj);
>             if (x.check()){
>                 std::string str = x();
>                 *strPtr = new char[str.length()+1];
>                 strcpy_s(*strPtr, str.length()+1, str.c_str());
>             }else{
>                 *strPtr = NULL;
>             }
>             inst.%s = *strPtr;
>         }
>         static boost::python::object get_%s(%s& inst){
>             std::string str;
>             if(inst.%s != NULL){
>                 std::string str(inst.%s);
>                 return bp::object(str);
>             }else{
>                 return bp::object();
>             }
>         }
>         """ % (varName, varName, className, varName, varName, varName,
> className, varName, varName)
>     wrapClass.add_wrapper_code(wrapperCode)
>
>     constructorCode = "wrap_%s = NULL;" % (varName)
>     add_constructors_body(wrapClass, constructorCode)
>
>     registrationCode = 'add_property("%s", &%s::get_%s, &%s::set_%s)' %
> (varName, wrapAlias, varName, wrapAlias, varName)
>     wrapClass.add_registration_code(registrationCode)

As for me you have few problems in this code:
* memory management
  you "set..." function allocates the memory, but you don't release
it. If you have many instances created\destroyed during program
execution you will have serious memory leak
  I would use boost::scoped_ptr (
http://www.boost.org/doc/libs/1_35_0/libs/smart_ptr/scoped_ptr.htm )
or just plain std::string classes
* readability
  wrapperCode contains too many "%s" and it is really difficult to
follow what is going on and modify it letter. I suggest you to use
string.Template class( http://www.python.org/doc/2.5.2/lib/node40.html
). I am sure, you will be pleased with the result.



-- 
Roman Yakovenko
C++ Python language binding
http://www.language-binding.net/

Re: [pygccxml-development] char *variables

[Gordon W. <gor...@gm...>]

 > * memory management

Oops, forgot to free it in the destructor, thanks for that.  I will look
into that scoped_ptr thing

> * readability

I already changed it to use a dictionary on the string formatting which
makes it much more readable.

On Sun, Jul 13, 2008 at 3:14 PM, Roman Yakovenko <rom...@gm...>
wrote:

> On Fri, Jul 11, 2008 at 6:51 AM, Gordon Wrigley
> <gor...@gm...> wrote:
> > I have my char *variables working now, here's the current py++ code I am
> > using, any comments would be appreciated
> >
> > for (className, varName) in stringVars:
> >     wrapClass = mb.class_(className)
> >     wrapClass.var(varName).exclude()
> >     wrapAlias = wrapClass.wrapper_alias
> >
> >     wrapperCode = """
> >         char *wrap_%s;
> >         void set_%s(%s& inst, bp::object obj){
> >             char **strPtr = &wrap_%s;
> >             if(*strPtr != NULL) delete *strPtr;
> >             bp::extract<std::string> x(obj);
> >             if (x.check()){
> >                 std::string str = x();
> >                 *strPtr = new char[str.length()+1];
> >                 strcpy_s(*strPtr, str.length()+1, str.c_str());
> >             }else{
> >                 *strPtr = NULL;
> >             }
> >             inst.%s = *strPtr;
> >         }
> >         static boost::python::object get_%s(%s& inst){
> >             std::string str;
> >             if(inst.%s != NULL){
> >                 std::string str(inst.%s);
> >                 return bp::object(str);
> >             }else{
> >                 return bp::object();
> >             }
> >         }
> >         """ % (varName, varName, className, varName, varName, varName,
> > className, varName, varName)
> >     wrapClass.add_wrapper_code(wrapperCode)
> >
> >     constructorCode = "wrap_%s = NULL;" % (varName)
> >     add_constructors_body(wrapClass, constructorCode)
> >
> >     registrationCode = 'add_property("%s", &%s::get_%s, &%s::set_%s)' %
> > (varName, wrapAlias, varName, wrapAlias, varName)
> >     wrapClass.add_registration_code(registrationCode)
>
> As for me you have few problems in this code:
> * memory management
>  you "set..." function allocates the memory, but you don't release
> it. If you have many instances created\destroyed during program
> execution you will have serious memory leak
>  I would use boost::scoped_ptr (
> http://www.boost.org/doc/libs/1_35_0/libs/smart_ptr/scoped_ptr.htm )
> or just plain std::string classes
> * readability
>  wrapperCode contains too many "%s" and it is really difficult to
> follow what is going on and modify it letter. I suggest you to use
> string.Template class( http://www.python.org/doc/2.5.2/lib/node40.html
> ). I am sure, you will be pleased with the result.
>
>
>
> --
> Roman Yakovenko
> C++ Python language binding
> http://www.language-binding.net/
>

Re: [pygccxml-development] char *variables

[Gordon W. <gor...@gm...>]

> I would use boost::scoped_ptr

I really don't see how that is supposed to work given that scoped pointers
are subject to this restriction "If used as a member of a class, must be
assigned in the constructor"

> I suggest you to use string.Template class. I am sure, you will be pleased
with the result.

and I am pleased with the result, thank you

On Sun, Jul 13, 2008 at 3:14 PM, Roman Yakovenko
<rom...@gm...>wrote:

> On Fri, Jul 11, 2008 at 6:51 AM, Gordon Wrigley
> <gor...@gm...> wrote:
> > I have my char *variables working now, here's the current py++ code I am
> > using, any comments would be appreciated
> >
> > for (className, varName) in stringVars:
> >     wrapClass = mb.class_(className)
> >     wrapClass.var(varName).exclude()
> >     wrapAlias = wrapClass.wrapper_alias
> >
> >     wrapperCode = """
> >         char *wrap_%s;
> >         void set_%s(%s& inst, bp::object obj){
> >             char **strPtr = &wrap_%s;
> >             if(*strPtr != NULL) delete *strPtr;
> >             bp::extract<std::string> x(obj);
> >             if (x.check()){
> >                 std::string str = x();
> >                 *strPtr = new char[str.length()+1];
> >                 strcpy_s(*strPtr, str.length()+1, str.c_str());
> >             }else{
> >                 *strPtr = NULL;
> >             }
> >             inst.%s = *strPtr;
> >         }
> >         static boost::python::object get_%s(%s& inst){
> >             std::string str;
> >             if(inst.%s != NULL){
> >                 std::string str(inst.%s);
> >                 return bp::object(str);
> >             }else{
> >                 return bp::object();
> >             }
> >         }
> >         """ % (varName, varName, className, varName, varName, varName,
> > className, varName, varName)
> >     wrapClass.add_wrapper_code(wrapperCode)
> >
> >     constructorCode = "wrap_%s = NULL;" % (varName)
> >     add_constructors_body(wrapClass, constructorCode)
> >
> >     registrationCode = 'add_property("%s", &%s::get_%s, &%s::set_%s)' %
> > (varName, wrapAlias, varName, wrapAlias, varName)
> >     wrapClass.add_registration_code(registrationCode)
>
> As for me you have few problems in this code:
> * memory management
>  you "set..." function allocates the memory, but you don't release
> it. If you have many instances created\destroyed during program
> execution you will have serious memory leak
>  I would use boost::scoped_ptr (
> http://www.boost.org/doc/libs/1_35_0/libs/smart_ptr/scoped_ptr.htm )
> or just plain std::string classes
> * readability
>  wrapperCode contains too many "%s" and it is really difficult to
> follow what is going on and modify it letter. I suggest you to use
> string.Template class( http://www.python.org/doc/2.5.2/lib/node40.html
> ). I am sure, you will be pleased with the result.
>
>
>
> --
> Roman Yakovenko
> C++ Python language binding
> http://www.language-binding.net/
>