Re: [f2py] f2py AttributeError

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Hi,

While Python is case-sensitive, Fortran is not.

In Fortran, foo, Foo, FOO, fOo, etc are all the same while at the object
code level they are all referred with unique (in general, compiler
dependent) name: foo_
By default, f2py also mangles the Fortran names by lowering the cases and
that is why RK4 appears as rk4 in the wrapper module.

To avoid this kind of surprises (there could be more, for instance, Fortran
intent(out) arguments are return values in the corresponding Python wrapper
functions), it is always recommended to print out the documentation strings
of wrapper modules and functions. For instance, see

print lib1.__doc__
print lin1.aa.__doc__

This is all explained in f2py docs.

Best regards,
Pearu


On Sat, Mar 2, 2013 at 9:55 PM, Gabor Kalman <[email protected]> wrote:

>   *I hope that  I can save someone=92s time with the following message:*
>
> I wrote a small script in gfortran:
> !-----------------------
> file: *RK4-test.f90*
>
> module aa
>
> subroutine RK4(args)   !!!please note RK4 is in all CAPS
> ...
> end subroutine RK4
> ....
>
> end module aa
> !------------------------------------
> then compiled it into *lib1.pyd*
>
> then with the f2py  driver:
> #------------------------------
> *test.py*
>
> import lib1
> s=3Dlib1.aa.RK4(args)
> print s
> #------------------------------
> I got an obscure message:   *AttributeError in RK4*
> **
> After a lot of searches I was ready to give up,
> but then I ACCIDENTLY Ire-wrote the driver as:
> #-------------------------------------------
> *test.py*
>
> import lib1
> s=3Dlib1.aa.rk4(args)  !!!please note rk4 in LOWER-CASE
> print s
> #----------------------------------------
> and  SUDDENLY everything worked OK!!!!
>
> Yes, while I know Python is* case-sensitive*, but this still surprised me=
.
>
>
>
>
> _______________________________________________
> f2py-users mailing list
> f2py-users-Y4l6ocDipWCuvFJfX82//[email protected]
> http://cens.ioc.ee/mailman/listinfo/f2py-users
>
>

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<div dir=3D"ltr"><div><div>Hi,<br><br></div>While Python is case-sensitive,=
 Fortran is not.<br></div><div><br>In Fortran, foo, Foo, FOO, fOo, etc are =
all the same while at the object code level they are all referred with uniq=
ue (in general, compiler dependent) name: foo_<br>
</div><div>By default, f2py also mangles the Fortran names by lowering the =
cases and that is why RK4 appears as rk4 in the wrapper module.<br><br></di=
v><div>To avoid this kind of surprises (there could be more, for instance, =
Fortran intent(out) arguments are return values in the corresponding Python=
 wrapper functions), it is always recommended to print out the documentatio=
n strings of wrapper modules and functions. For instance, see<br>
<br></div><div>print lib1.__doc__<br></div><div>print lin1.aa.__doc__<br></=
div><div><br></div><div>This is all explained in f2py docs.<br></div><div><=
br></div><div>Best regards,<br></div>Pearu<br></div><div class=3D"gmail_ext=
ra">
<br><br><div class=3D"gmail_quote">On Sat, Mar 2, 2013 at 9:55 PM, Gabor Ka=
lman <span dir=3D"ltr">&lt;<a href=3D"mailto:[email protected]" target=
=3D"_blank">[email protected]</a>&gt;</span> wrote:<br><blockquote class=
=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padd=
ing-left:1ex">

<div dir=3D"ltr">
<div dir=3D"ltr">
<div style=3D"font-size:12pt;font-family:&#39;Calibri&#39;">
<div><font size=3D"5"><strong>I hope that=A0 I can save someone=92s time wi=
th the=20
following message:</strong></font></div>
<div>=A0</div>
<div>I wrote a small script in gfortran:</div>
<div>!-----------------------</div>
<div>file: <strong>RK4-test.f90</strong></div>
<div>=A0</div>
<div>module aa</div>
<div>=A0</div>
<div>subroutine RK4(args)=A0=A0 !!!please note RK4 is in all CAPS</div>
<div>...</div>
<div>end subroutine RK4</div>
<div>....</div>
<div>=A0</div>
<div>end module aa</div>
<div>!------------------------------------</div>
<div>then compiled it into <strong>lib1.pyd</strong></div>
<div>=A0</div>
<div>then with the f2py=A0 driver:</div>
<div>#------------------------------</div>
<div><strong>test.py</strong></div>
<div>=A0</div>
<div>import lib1</div>
<div>s=3Dlib1.aa.RK4(args)</div>
<div>print s</div>
<div>#------------------------------</div>
<div>I got an obscure message:=A0=A0 <strong>AttributeError in=20
RK4</strong></div>
<div><strong></strong>=A0</div>
<div>After a lot of searches I was ready to give up,</div>
<div>but then I ACCIDENTLY Ire-wrote the driver as:</div>
<div>#-------------------------------------------</div>
<div><strong>test.py</strong></div>
<div>=A0</div>
<div>import lib1</div>
<div>s=3Dlib1.aa.rk4(args)=A0 !!!please note rk4 in LOWER-CASE</div>
<div>print s</div>
<div>#----------------------------------------</div>
<div>and=A0 SUDDENLY everything worked OK!!!!</div>
<div>=A0</div>
<div>Yes, while I know Python is<strong> case-sensitive</strong>, but this =
still=20
surprised me.</div>
<div>=A0</div>
<div>=A0</div>
<div>=A0</div></div></div></div>
<br>_______________________________________________<br>
f2py-users mailing list<br>
<a href=3D"mailto:f2py-users-Y4l6ocDipWCuvFJfX82//[email protected]">f2py-users-Y4l6ocDipWCuvFJfX82//[email protected]</a><br>
<a href=3D"http://cens.ioc.ee/mailman/listinfo/f2py-users" target=3D"_blank=
">http://cens.ioc.ee/mailman/listinfo/f2py-users</a><br>
<br></blockquote></div><br></div>

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