swig & Python question

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  • It's me
    #1

    swig & Python question

    I am playing around with SWING building a Python module using the no brainer
    example in http://www.swig.org/tutorial.html. With that first example,


    /* File : example.c */

    #include <time.h>
    double My_variable = 3.0;

    int fact(int n) {
    if (n <= 1) return 1;
    else return n*fact(n-1);
    }

    int my_mod(int x, int y) {
    return (x%y);
    }

    char *get_time()
    {
    time_t ltime;
    time(&ltime);
    return ctime(&ltime);
    }
    and using the swig file of:
    /* example.i */
    %module example
    %{
    /* Put header files here (optional) */
    %}

    extern double My_variable;
    extern int fact(int n);
    extern int my_mod(int x, int y);
    extern char *get_time();
    I was able to execute this Python script:

    [color=blue][color=green][color=darkred]
    >>> import example
    >>> example.fact(5)[/color][/color][/color]
    120[color=blue][color=green][color=darkred]
    >>> example.my_mod( 7,3)[/color][/color][/color]
    1[color=blue][color=green][color=darkred]
    >>> example.get_tim e()[/color][/color][/color]
    'Sun Feb 11 23:01:07 1996'[color=blue][color=green][color=darkred]
    >>>[/color][/color][/color]
    However, when I try to access the gloabl variable My_variable by doing:

    print example.cvar

    I get a blank (rather then a value of 3.0).

    Why?

    --
    It's me


    Tags: None
    • It's me
      #2
      Re: swig &amp; Python question


      "It's me" <itsme@yahoo.co m> wrote in message
      news:oDStd.3107 6$zx1.23489@new ssvr13.news.pro digy.com...[color=blue]
      > I am playing around with SWING building a Python module using the no[/color]
      brainer[color=blue]
      > example in http://www.swig.org/tutorial.html. With that first example,
      >[/color]

      Oops! Soapy fingers. "SWIG" - not "SWING".

      --
      It's me.


        Comment

        • Keith Dart
          #3
          Re: swig &amp; Python question

          It's me wrote:[color=blue]
          > "It's me" <itsme@yahoo.co m> wrote in message
          > news:oDStd.3107 6$zx1.23489@new ssvr13.news.pro digy.com...
          >[color=green]
          >>I am playing around with SWING building a Python module using the no[/color]
          >
          > brainer
          >[color=green]
          >>example in http://www.swig.org/tutorial.html. With that first example,
          >>[/color]
          >
          >
          > Oops! Soapy fingers. "SWIG" - not "SWING".
          >
          > --
          > It's me.[/color]

          I have used SWIG before, and it's not always such a "no-brainer". In
          fact, it rarely is except for trivial examples. But it can work. I think
          it is best suited for wrapping large libraries. For small stuff, it
          would be better to just do it "manually" using the Python C API.


          Good luck.

          --
          It's not me.




          --
          \/ \/
          (O O)
          -- --------------------oOOo~(_)~oOOo----------------------------------------
          Keith Dart <kdart@kdart.co m>
          public key: ID: F3D288E4
          =============== =============== =============== =============== =============== =

            Comment

            • It's me
              #4
              Re: swig &amp; Python question

              Whether SWIG will work in a "no brainer" way or not depends on the original
              code, I think. If the original code uses a very convoluted design, of
              course things will get hairy. If the package uses a very clean structure,
              I think you will find SWIG works out very nicely.

              The intriguing things is, however, once you structure the package to a form
              SWIG would work, it opens up the door to support multiple script languages
              (and they have a long list of supported script languages).

              If you hand crafted it to run the Python-C API, then you can only use Python
              as script.

              --
              It's me


              "Keith Dart" <kdart@kdart.co m> wrote in message
              news:41BAD6F0.6 020509@kdart.co m...[color=blue]
              > It's me wrote:[color=green]
              > > "It's me" <itsme@yahoo.co m> wrote in message
              > > news:oDStd.3107 6$zx1.23489@new ssvr13.news.pro digy.com...
              > >[color=darkred]
              > >>I am playing around with SWING building a Python module using the no[/color]
              > >
              > > brainer
              > >[color=darkred]
              > >>example in http://www.swig.org/tutorial.html. With that first example,
              > >>[/color]
              > >
              > >
              > > Oops! Soapy fingers. "SWIG" - not "SWING".
              > >
              > > --
              > > It's me.[/color]
              >
              > I have used SWIG before, and it's not always such a "no-brainer". In
              > fact, it rarely is except for trivial examples. But it can work. I think
              > it is best suited for wrapping large libraries. For small stuff, it
              > would be better to just do it "manually" using the Python C API.
              >
              >
              > Good luck.
              >
              > --
              > It's not me.
              >
              >
              >
              >
              > --
              > \/ \/
              > (O O)
              > -- --------------------oOOo~(_)~oOOo--------------------------------------[/color]
              --[color=blue]
              > Keith Dart <kdart@kdart.co m>
              > public key: ID: F3D288E4
              >[/color]
              =============== =============== =============== =============== =============== =


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