Re: ctypes - swig - pointer

[Jean-Paul Calderone]

On Mon, 30 Jun 2008 09:13:42 -0700 (PDT), gianluca <geonomica@gmai l.comwrote:

>I've a problem with dll function colled with python/ctypes. My
>functions (C) requred a typedef int "value_type " in tree different
>way:
>same as value_type; - mydll.foo1(valu e_type)
>same as *value_type; - mydll.foo2(*val ue_type)
>same as **value_type; - mydll.foo3(**va lue_type)
>
>How can pass it in python. If i do that:
>rules=POINTER( value_type)
>opr=rsl.Streng thOfRules(rules ,10)
>R=POINTER(rule s)

POINTER takes a class and returns a new class which represents a pointer
to input class.

pointer takes an instance and returns a new object which represents a
pointer to that instance.

Jean-Paul

[gianluca]

Re: ctypes - swig - pointer

On 30 Giu, 18:26, Jean-Paul Calderone <exar...@divmod .comwrote:

On Mon, 30 Jun 2008 09:13:42 -0700 (PDT), gianluca <geonom...@gmai l.comwrote:

I've a problem with dll function colled with python/ctypes. My
functions (C) requred a typedef int "value_type " in tree different
way:
same as value_type; - mydll.foo1(valu e_type)
same as *value_type; - mydll.foo2(*val ue_type)
same as **value_type; - mydll.foo3(**va lue_type)

>

How can pass it in python. If i do that:
rules=POINTER(v alue_type)
opr=rsl.Strengt hOfRules(rules, 10)
R=POINTER(rules )

>
POINTER takes a class and returns a new class which represents a pointer
to input class.
>
pointer takes an instance and returns a new object which represents a
pointer to that instance.
>
Jean-Paul

so,
if I write this:
p=pointer(value _type)
mydll.foo1(p)
could be correct but python say me:
TypeError: _type_ must have storage info
what does mean?

thank you

gima

[Mark Tolonen]

Re: ctypes - swig - pointer


"gianluca" <geonomica@gmai l.comwrote in message
news:58461c91-ed11-4153-8d74-429353e4fdd1@z7 2g2000hsb.googl egroups.com...

On 30 Giu, 18:26, Jean-Paul Calderone <exar...@divmod .comwrote:

>On Mon, 30 Jun 2008 09:13:42 -0700 (PDT), gianluca <geonom...@gmai l.com>
>wrote:

>I've a problem with dll function colled with python/ctypes. My
>functions (C) requred a typedef int "value_type " in tree different
>way:
>same as value_type; - mydll.foo1(valu e_type)
>same as *value_type; - mydll.foo2(*val ue_type)
>same as **value_type; - mydll.foo3(**va lue_type)

>>

>How can pass it in python. If i do that:
>rules=POINTER( value_type)
>opr=rsl.Streng thOfRules(rules ,10)
>R=POINTER(rule s)

>>
>POINTER takes a class and returns a new class which represents a pointer
>to input class.
>>
>pointer takes an instance and returns a new object which represents a
>pointer to that instance.
>>
>Jean-Paul

>
so,
if I write this:
p=pointer(value _type)
mydll.foo1(p)
could be correct but python say me:
TypeError: _type_ must have storage info
what does mean?
>
thank you
>
gima

It means you cannot create a pointer to a type, you need to provide an
instance of a type:

>>from ctypes import *
>>px=pointer(c_ int)

Traceback (most recent call last):
File "<interacti ve input>", line 1, in <module>
File "C:\dev\python\ lib\ctypes\__in it__.py", line 282, in pointer
return POINTER(type(in st))(inst)
File "C:\dev\python\ lib\ctypes\__in it__.py", line 226, in POINTER
{'_type_': cls})
TypeError: _type_ must have storage info

>>x=c_int(5) # make an instance (C equiv. is "int x=5;")
>>px=pointer( x) # int* px = &x;
>>ppx=pointer(p x) # int** ppx = &px;
>>x

c_long(5)

>>px

<ctypes.LP_c_lo ng object at 0x00E87350>

>>ppx

<ctypes.LP_LP_c _long object at 0x00E873A0>

--Mark