On 11/05/2010 10:19 PM, Robert Bradshaw wrote: > On Fri, Nov 5, 2010 at 6:12 PM, Martin Albrecht > <martinralbre...@googlemail.com> wrote: >> in the Sage library we cannot write the following C++ code: >> >> Class a = Class() >> >> since Cython turns the statement >> >> cdef Class a = Class() >> >> into >> >> Class a >> a = Class() >> >> which only works when there is a copy constructor. In the Sage library we >> sometimes use the follow construct in order to work around this Cython vs. >> C++ >> incompatibility: >> >> Class a >> Construct<Class>(&a) >> >> For example check the PolyBoRi wrapper and the NTL wrapper. There are also >> variants of this called Construct_p<Class>(&a, one_parameter) and so forth. >> >> I'm wrapping CryptoMiniSat at the moment (a general purpose (!) SAT solver >> which one this year's SAT Race). When I try to use this construct in my >> wrapper I get a complaint from g++ that Construct wasn't defined in the >> scope; yet I cannot see what we are doing special in the PolyBoRi or NTL >> wrapper which would have an affect on that. Also searching online for this >> construction also returned nothing of interest as far as I can tell, mainly >> because one is overwhelmed with C++ constructor introductions. Thus, my >> question: does any of you C++ gurus now where this thing is defined and what >> I >> have to do (or not to do) in order to use it?
I'm not a guru, but is it defined in SAGE_ROOT/devel/sage/c_lib/include/ccobject.h ? Both ntl_wrap.h and pb_wrap.h include this file. > If heap-allocated instances are fast enough, you can use the much > easier C++ support (recently merged into Sage): > > cdef Class *a = new Class() > del a > > What we use in Sage is probably buried in some .h file. I think the > official term is "placement new" where we allocate a chunk of the > Python object struct to hold the data. -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
