Mailman 3 November 2000 - Cplusplus-sig

Problems using iostreams or string with Python?
by tom＠malcolmson.com Dec. 10, 2000

Dec. 10, 2000

I have seen it reported that the C++ iostreams library (and the C++ string class, which uses iostreams) should never be mixed with the C streams library. Given that Python uses the C streams library, does this mean that I can't use C++ iostreams with Python related code? Thanks, Tom.

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Re: [c++-sig] Digest Number 55
by David Abrahams Nov. 17, 2000

Nov. 17, 2000

> From: "Belopolsky, Alexander" <alexander.belopolsky(a)gs.com> > Subject: RE: Digest Number 54 > > Yes this is in the standard: > > ISO/IEC 148882:1998(E) Section 27.4.2.4 [lib.ios.members.static] So it is. And a big "whoops, sorry!" to all. -Dave

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RE: [c++-sig] Digest Number 54
by Belopolsky, Alexander Nov. 16, 2000

Nov. 16, 2000

Yes this is in the standard: ISO/IEC 148882:1998(E) Section 27.4.2.4 [lib.ios.members.static] --alex -----Original Message----- From: mark.mcmahon(a)eur.autodesk.com [mailto:mark.mcmahon@eur.autodesk.com] Sent: Thursday, November 16, 2000 9:21 AM To: c++-sig(a)python.org Subject: RE: [c++-sig] Digest Number 54 It is actually part of the standard (of which I do not have) but http://www.claas-solutions.de/iostreams/ios_base.html M > Or you could use sync_with_stdio

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RE: [c++-sig] Digest Number 54
by mark.mcmahon＠eur.autodesk.com Nov. 16, 2000

Nov. 16, 2000

It is actually part of the standard (of which I do not have) but http://www.claas-solutions.de/iostreams/ios_base.html M -----Original Message----- From: David Abrahams [mailto:abrahams@mediaone.net] Sent: 16 November 2000 15:15 To: mark.mcmahon(a)eur.autodesk.com; c++-sig(a)python.org Subject: Re: [c++-sig] Digest Number 54 That's a nonstandard and thus nonportable feature of one particular standard library implementation. The OP didn't say which platform he was using. -Dave ----- Original Message ----- From: <mark.mcmahon(a)eur.autodesk.com> > Or you could use sync_with_stdio > > ----- copy from MSDN ----------- > ios_base::sync_with_stdio > > static bool sync_with_stdio(bool sync = true); > > The static member function stores a stdio sync flag, which is initially true. When true, this flag ensures that operations on the same file are properly synchronized between the iostreams functions and those defined in the Standard C library. Otherwise, synchronization may or may not be guaranteed, but performance may be improved. The function stores sync in the stdio sync flag and returns its previous stored value. You can call it reliably only before performing any operations on the standard streams. > -------------------------------- _______________________________________________ C++-SIG maillist - C++-SIG(a)python.org http://www.python.org/mailman/listinfo/c++-sig

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RE: [c++-sig] Digest Number 54
by mark.mcmahon＠eur.autodesk.com Nov. 16, 2000

Nov. 16, 2000

Or you could use sync_with_stdio ----- copy from MSDN ----------- ios_base::sync_with_stdio static bool sync_with_stdio(bool sync = true); The static member function stores a stdio sync flag, which is initially true. When true, this flag ensures that operations on the same file are properly synchronized between the iostreams functions and those defined in the Standard C library. Otherwise, synchronization may or may not be guaranteed, but performance may be improved. The function stores sync in the stdio sync flag and returns its previous stored value. You can call it reliably only before performing any operations on the standard streams. -------------------------------- -----Original Message----- From: David Abrahams [mailto:abrahams@mediaone.net] Sent: 16 November 2000 14:29 To: c++-sig(a)python.org Subject: Re: [c++-sig] Digest Number 54 > From: tom(a)malcolmson.com (Tom) > I have seen it reported that the C++ iostreams library (and the C++ string > class, which uses iostreams) should never be mixed with the C streams > library. I've seen it reported that if you eat pop rocks and drink coke, your stomach will explode ;-) > Given that Python uses the C streams library, does this mean that I can't > use C++ iostreams with Python related code? No. On the other hand, if you want to write to stdout/stderr coherently, using std::cout/std::cerr to do it may have surprising results, since they are buffered separately from the 'C' streams. There's a lot more to C++ iostreams than just cout/cerr, though. For example, you can make an ostreambuf that writes to a 'C' FILE stream, or you can write to an ostringstream and then write its contents into stdout yourself (less convenient, but easier to implement). that's-what-happened-to-mikey-you-know-the-life-cereal-kid-ly y'rs dave _______________________________________________ C++-SIG maillist - C++-SIG(a)python.org http://www.python.org/mailman/listinfo/c++-sig

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Re: [c++-sig] Digest Number 54
by David Abrahams Nov. 16, 2000

Nov. 16, 2000

> From: tom(a)malcolmson.com (Tom) > I have seen it reported that the C++ iostreams library (and the C++ string > class, which uses iostreams) should never be mixed with the C streams > library. I've seen it reported that if you eat pop rocks and drink coke, your stomach will explode ;-) > Given that Python uses the C streams library, does this mean that I can't > use C++ iostreams with Python related code? No. On the other hand, if you want to write to stdout/stderr coherently, using std::cout/std::cerr to do it may have surprising results, since they are buffered separately from the 'C' streams. There's a lot more to C++ iostreams than just cout/cerr, though. For example, you can make an ostreambuf that writes to a 'C' FILE stream, or you can write to an ostringstream and then write its contents into stdout yourself (less convenient, but easier to implement). that's-what-happened-to-mikey-you-know-the-life-cereal-kid-ly y'rs dave

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Re: Problem with last version of py_cpp
by David Abrahams Nov. 9, 2000

Nov. 9, 2000

> From: Xavier JUVIGNY <Xavier.Juvigny(a)onera.fr> > Subject: Problem with last version of py_cpp > > Hi, > > I try to use the last version of py_cpp on a Unix station with gcc > 2.95.1 > <snip> > Has anyone a idea ? First, as your function takes more than 5 arguments, you'll need to run: > gen_all.py xxx where xxx >= the most arguments you need to handle in the py_cpp directory. This will generate code to support more arguments. I think you may want to grab an updated copy of gen_extclass.py first, though, from: http://cvs.sourceforge.net/cgi-bin/cvsweb.cgi/boost/development/py_cpp/gen_e xtclass.py?cvsroot=boost as I believe we fixed a bug in the past few days. Also, I suggest you get gcc 2.95.2, as 2.95.1 is not supported with py_cpp. Regards, Dave

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Problem with last version of py_cpp
by Xavier JUVIGNY Nov. 8, 2000

Nov. 8, 2000

Hi, I try to use the last version of py_cpp on a Unix station with gcc 2.95.1 I had a problem with a method with three arguments. The folowing example : #include <py_cpp/class_wrapper.h> class A { public: A() {} void f(int,int,int,float,float,float) { } }; void initMesh() { try { // Create the object representing this extension module py::Module PyA("A"); // Create the Python type object for our extension class. py::ClassWrapper<A> A_class(PyA, "PyA"); // A_class.def(&A::f, "f"); } catch(...) { py::handle_exception(); } } give me the unexcepted error : /data/Wksp/juvigny/Decoupeur.d/py_cpp/functions.h: In function `class py::Function * py::new_wrapped_function<void (A::*)(int, int, int, float, float, float)>(void (A::*)(int, int, int, float, float, float))': /data/Wksp/juvigny/Decoupeur.d/py_cpp/extclass.h:371: instantiated from `py::ExtensionClass<A,py::HeldInstance<A> >::def<void (A::*)(int, int, int, float, float, float)>(void (A::*)(int, int, int, float, float, float), const char *)' /data/Wksp/juvigny/Decoupeur.d/py_cpp/class_wrapper.h:35: instantiated from `py::ClassWrapper<A,py::HeldInstance<A> >::def<void (A::*)(int, int, int, float, float, float)>(void (A::*)(int, int, int, float, float, float), const char *)' Py_A.C:22: instantiated from here /data/Wksp/juvigny/Decoupeur.d/py_cpp/functions.h:127: no matching function for call to `return_value (void (A::* &)(int, int, int, float, float, float))' Has anyone a idea ? Thanks for help. Juvigny Xavier

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Yet another py_cpp update
by David Abrahams Nov. 6, 2000

Nov. 6, 2000

Available at http://www.egroups.com/files/boost/py_cpp/py_cpp_20001106.zip or http://people.ne.mediaone.net/abrahams/downloads/py_cpp.html -Dave Changes since last release: 2000-11-06 0:22 Lots of documentation updates added 4-argument template constructor to py::Tuple added "add" member function to ClassWrapper<> to allow arbitrary Python objects to be added to an extension class. gen_all.py now generates support for n argument member functions and n+1 argument member functions at the suggestion of "Ralf W. Grosse-Kunstleve" <rwgk(a)cci.lbl.gov> Added regression tests and re-ordered declare_base calls to verify that the phantom base class issue is resolved. 2000-11-04 17:35 Integrated Ullrich Koethe's brilliant from_python_experiment for better error-reporting in many cases. extclass.h, gen_extclass.py: removed special-case MSVC code added much commentary removed unused py_copy_to_new_value_holder init_function.h, gen_init_function.py: added missing 'template' keyword on type-dependent template member usage removed special-case MSVC code added much commentary 2000-11-04 0:36 Removed the need for the phantom base class that screwed up inheritance hierarchies, introduced error-prone ordering dependencies, and complexified logic in many places! extclass.h: Added some explanatory comments, removed wasteful m_self member of HeldInstance extclass_demo.cpp: Added #pragmas which allow compilation in ansi strict mode under Metrowerks functions.h: Added virtual_function as part of phantom base class removal; expanded commentary pyptr.h: Added some missing 'typename's and a GCC workaround fix subclass.cpp: Added missing string literal const_cast<>s. 2000-11-03 10:58 Fix friend function instantiation bug caught by Metrowerks (thanks Metrowerks!) Add proof-of-concept for one technique of wrapping function that return a pointer Worked around MSVC optimizer bug by writing to_python(double) and to_python(float) out-of-line 2000-11-02 23:25 Add /Zm200 option to vc6_prj to deal with MSVC resource limitations Remove conflicting /Ot option from vc6_prj release build

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test - please ignore
by David Abrahams Nov. 3, 2000

Nov. 3, 2000

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