- Boost-users - lists.preview.boost.org

Typelists.
by jamescurran＠mvps.org 28 Nov '01

28 Nov '01

Over on the Boost Developer group, there a lot of talk about how to best implement a typelist. Just so I can follow that discussion, could someone give me the basic thumbnail sketch of what exactly a typelist is, and what they are used for?

3 2

Real-world applications using Boost - results
by Björn Karlsson 27 Nov '01

27 Nov '01

I recently posted a question about "real-world" use of Boost. The (surprisingly few) answers I received can be found at the end of the e-mail. I think it is safe to say that the usage is more widely spread than the answers indicate. [Note: I have excluded the names from the e-mails, although not explicitly asked to do so.] Summary: There were replies from 8 Boosters. It seems that the lightweight utility classes are the most popular, likely due to the fact that their impact on existing systems is easily manageable. Thank you for your answers! Bjorn Karlsson Reply ////////////////////////////////////////////////////////////////////////// Using some small parts of it. Selected because it lets you pick and chose things to use from a large set of (relatively) small components/tools rather than ending up "buying into" some grand scheme of things. Well designed small interfaces rather than including the kitchen sink, making it easier for people to pick up/maintain code later.... Did what I needed to do at the time.... Note that the things I have elected to use so far have been small and intended to reduce the risk of mistakes (eg operators, traits) rather than anything vast. Reply [translated] ////////////////////////////////////////////////////////////////////////// We have just started to use Boost for converting a Python prototype to C++. The experience is still limited, but the results after a few days of work are very good. Reply ////////////////////////////////////////////////////////////////////////// I'm using Boost heavily in FEMTown (www.femtown.org) FEMTown is an open-source finite-element framework in development. We're using Boost because it provides stable and slim functionality that helps us making FEMTown more efficient, flexible and robust. (although our choice of C++ for a scientific application is even kinda controversial) Reply ////////////////////////////////////////////////////////////////////////// At this moment, I'm using the Boost lexical_cast in one of our commercial software products (Pilot - see http://www.leitch.com/custserv/products.nsf/lookup/CCS-PILOT) I needed to convert from integers to text for transmission across the network, then back from text to integer value. I had been using strstream, but the lexical_cast wrapped all the complexity up for me. I chose Boost because it's portable (our software runs on Windows NT and on embedded software using gcc). I knew there is a good chance that lexical_cast will become a standard keyword. As I learn more about the various libraries that are available, I will likely find appropriate places to use them. Reply ////////////////////////////////////////////////////////////////////////// My group is currently using Boost on one project as an experiment. We do cross-platform Macintosh/Windows development and it was valuable to have a tested library that worked on our two main development platforms. We have been phasing different parts of Boost in as come across problems that Boost will solve. As a community I find Boost a source of best practices that I have tried to implement in our workplace. Reply ////////////////////////////////////////////////////////////////////////// We've been using Boost at Zetec for over two years. Initially just for shared_ptr, but since expanding to lexical_cast, iterator_adaptors, tokenizer, and others. If you need any other info, let me know. Reply ////////////////////////////////////////////////////////////////////////// I am starting a new project using boost. It is a financial risk-management engine. I cannot tell you a lot about it yet. We are a team of 8 developers, 4 developing the backend and 4 developing the interfaces. The product will hopefully be a big success in the financial world as it is developed in cooperation with some the best people of the financial industry. It is a 12 months development effort using the XP development process. boost will be used to provide some utility classes (smart pointers, anys, threads ... ). The engine will run on Solaris and Linux. A future version on Windows may exist in the future. Reply ////////////////////////////////////////////////////////////////////////// We've used small parts of Boost in a digital video distribution back-end system; the system was developed by a client of us(us=CMG). If you want names in your summary I'd have to ask for permissions from them.

1 0

(no subject)
by Paul Grenyer 25 Nov '01

25 Nov '01

Paul Grenyer pjgrenyer(a)iee.org

1 0

"referenced symbol not found" when loading modules
by dlrubin＠yahoo.com 25 Nov '01

25 Nov '01

I'm getting a "refernced symbol not found" error when loading modules compiled with Boost. I tried using boost using this example code: #include <stdio.h> #include <string> #include <boost/python/class_builder.hpp> namespace { std::string greet() { return "hello, world"; } int square(int number) { return number * number; } } namespace python = boost::python; BOOST_PYTHON_MODULE_INIT(example) { try { // Create an object representing this extension module. python::module_builder this_module("example"); // Add regular functions to the module. this_module.def(greet, "greet"); } catch(...) { python::handle_exception(); // Deal with the exception for Python } } and when I try importing into python, here's the error I get: Python 2.1.1 (#5, Nov 22 2001, 14:04:45) [GCC 2.95.2 19991024 (release)] on sunos5 Type "copyright", "credits" or "license" for more information. >>> import example Traceback (most recent call last): File "<stdin>", line 1, in ? ImportError: ld.so.1: python: fatal: relocation error: file ./example.so: symbol handle_exception__Q25boost6pythonv: referenced symbol not found Any suggestions? thanks, Daniel

1 0

Introducing Me
by Paul Grenyer 24 Nov '01

24 Nov '01

Dear All I don't know if this is the appropriate thing to do here (I'm sure the moderator will filter me out if it isn't), but I failed to introduce myself on other lists and with hindsight I think it would have been better if I had. I've been programming in C++ for about 18 months, since I left university and started working. I was introduced to the C++ standard library and boost libraries a few months ago by a member of the ACCU. I have just started a new job writing distributed software using the C++ standard library and the ATL and I'm making as much use of boost as possible. Previous to that I was writing windows software to control dot markers and laser markers using the MFC. So, I am very new to boost and am not expecting to be able to contribute much for a while and I'll no doubt need the odd nudge in the right direct. Thanks Paul Paul Grenyer pjgrenyer(a)iee.org

1 0

Re: [boost] how to get a *real* copy of a boost-python object that supports virtual function
by Phil Austin 24 Nov '01

24 Nov '01

(I'm posting to both boost and boost-users, but I'm assuming we're supposed to move this kind of discussion to Boost-Users(a)yahoogroups.com?) dkottowk(a)yahoo.com writes: [snip] > my question is, how do i get a copy of PyGenome_Callback, > which also is a copy of the python-side of the object ? I'd also be interested in a pointer to an elegant way to do this, as well as an example of a from_python function that converts PyObject* to PyGenome_Callback. Brute force does work for me -- i.e. if you need the derived class and can't construct the object in Python code, you can call the derived constructor from the C++ side like this: PyObject* theMod=PyImport_ImportModule("mymodule"); PyObject* theDict=PyModule_GetDict(theMod); py::ref theRef(theDict); py::dictionary modDict(theRef); py::ref constructor=bDict.get_item(py::string("theObject").reference()); PyObject* theInstance=PyObject_CallObject(constructor.get(),0); This was ugly enough so that I added a python wrapper around my extension to construct the derived objects I needed in Python and pass them back to C++. Phil

1 0

boost tokenizer
by pjgrenyer＠iee.org 23 Nov '01

23 Nov '01

Dear All I'm using the boost tokenizer to tokenise lines similar to this one: first_initial |23|1| This gives me: first initial 23 1 but what I actually want is: first_initial 23 1 Does anyone know how to get it to ignore the underscore? Thanks Paul

3 2

passing data to a thread
by d33pmind＠yahoo.fr 23 Nov '01

23 Nov '01

How can I pass data to a thread ? Why does the boost::thread's constructor takes a boost::function0<void> as parameter, instead of a boost::function1<void> which would have allowed to pass it a pointer to a thread safe structure ? Julien.

2 1

core dump when invoking jam
by d33pmind＠yahoo.fr 23 Nov '01

23 Nov '01

On a Linux Mandrake 8.1 (i586), I succesfully built jam, but when I invoke it I got no output except a core dump. Has anyone encountered the same problem ? I compiled it with gcc 3.0.1, and modified gcc-tools.jam to use gcc- 3.0.1 and g++-3.0.1 instead of gcc and g++ (which are 2.96). Thanks. Julien.

2 1

What's safe_bool?
by mr_lilirong＠yahoo.com 23 Nov '01

23 Nov '01

Hi, The following code is excerpted from Boost.Function. I just don't unstanding it. Why use "safe_bool"? What's the advantage? Can any one explain it to me? Thanks. // code from <boost/function/function_base.hpp> // ===> private: struct dummy { void nonnull() {}; }; typedef void (dummy::*safe_bool)(); public: operator safe_bool () const { return (this->empty())? 0 : &dummy::nonnull; } safe_bool operator!() const { return (this->empty())? &dummy::nonnull : 0; } // code from <boost/function/function_base.hpp> // <===

2 2