Hi all,
I have a problem with GcStruct, Struct and Ptr I can not resolve with my
own devices.
After some trial with ctypes running on CPython I came up with the
following lowlevel representation for structures:
Ptr( GcStruct( "CtypesGcStructure_<ClassName>
( "c_data"
(Struct "C-Data_<ClassName>
*<Fieldefintions>) ) ) )
Samuele and Armin helped to implement rtype_getattr and rtype_setattr
that delegate all attribute access to the c_data field, by pointing
out how to implement a helper method called generateCDataAccess:
def generateCDataAccess( self, variable, lowLevelOperations ):
"""
Answer the C level data sub structure.
"""
inputargs = [ variable, inputconst( Void, "c_data" ) ]
return lowLevelOperations.genop(
"getfield",
inputargs,
# Using Ptr makes the C-compiler barf,
# omitting Ptr leeds to specialisation errors
Ptr( self.c_data_lowleveltype ) )
def rtype_setattr( self, highLevelOperation ):
c_data = self.generateCDataAccess(
highLevelOperation.inputarg( self, 0 ),
highLevelOperation.llops )
inputargs = highLevelOperation.inputargs(
*highLevelOperation.args_r[ :3 ] )
inputargs[ 0 ] = c_data
print "inputargs:", inputargs
print "r_result:", highLevelOperation.r_result
highLevelOperation.genop( "setfield", inputargs )
Obviously generateCDataAccess needs to return a Ptr to the embedded
C-structure. When I use Ptr as in the example above, I get the following
traceback:
c:\Dokumente und Einstellungen\root\Lokale
Einstellungen\Temp\usession-353\testi
ng_2\testing_2.c(894) : error C2440: '=': 'pypy_C_Data_tagpoint0'
kann nicht in
'pypy_C_Data_tagpoint0 *' konvertiert werden
Which means, that a 'pypy_C_Data_tagpoint0' can not be converted to a
'pypy_C_Data_tagpoint0 *'. A brief look at the generated C-source,
shows that the compiler is right here:
struct pypy_CtypesStructure_tagpoint0
*pypy_g__py_test_compile_struct(struct pypy_CtypesStructure_tagpoint0
*l_p_0, long l_x_1, long l_y_1) {
/*void l_v111;*/ /*void l_v112;*/
struct pypy_C_Data_tagpoint0 *l_v98;
struct pypy_C_Data_tagpoint0 *l_v99;
struct pypy_CtypesStructure_tagpoint0 *l_v110;
pypy_IncRf_CtypesStructure_tagpoint0(l_p_0);
block0:
l_v98 = l_p_0->cs_c_data;
l_v98->cd_x = l_x_1;
l_v99 = l_p_0->cs_c_data;
l_v99->cd_y = l_y_1;
l_v110 = l_p_0;
goto block1;
block1:
return l_v110;
}
If I ommit the Ptr construction so that, generateCDataAccess is defined
as follows:
def generateCDataAccess( self, variable, lowLevelOperations ):
"""
Answer the C level data sub structure.
"""
inputargs = [ variable, inputconst( Void, "c_data" ) ]
return lowLevelOperations.genop(
"getfield",
inputargs,
self.c_data_lowleveltype )
I get the following error:
[D:\svnwork\work\dist\pypy\rpython\lltypesystem\lltype.py:146]
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
def _nofield(self, name):
raise AttributeError, 'struct %s has no field %r' %
(self._name,
E name)
> AttributeError: struct C-Data_tagpoint has no field 'TO'
This is no surprise at all. The getfield operation obviosly needs a
pointer to
work with.
So it boils down to the question:
How can I access the members of an embedded structure?
Is there a possibility to get the address of substructure, just like
C's ampersand (&) operator does?
Any help is welcome.
Best regards,
Gerald
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