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RE: [boost] VTL question (sorry if this is slightly off-topic)
by Powell, Gary 11 Feb '04

11 Feb '04

Hello, I was reviewing the View Template Library (VTL) - see http://www.zib.de/weiser/vtl/ ... and have a few questions regarding Views as applied to STL Maps. I was also wondering if Boost was planning to eventually provide a VTL-like framework? ---------------------------------- Gary > Yes, I'm planning on using the new Iterator Adaptors and converting the VTL library to use boost. --------------------------- I'm looking for a type of View that provides read-only access to an STL map, with only const iterators, but also provides limited insertion and removal access as well (as shown below): This new limited View-like map will only allow clients to iterate using const iterators, and also provides only one public insert(const key&) and one erase(const key&) method. These insert and erase member functions need to be implemented as "Template Method Functions", as follows: (see Design Patterns) * Note: these are shown using the latest SGI STL implementation (i.e., the _M_t.insert_unique and _M_t.erase calls) virtual bool preInsert(const value_type&) { return true; } pair<iterator, bool> insert(const value_type& x) { if(preInsert(x) { return _M_t.insert_unique(x); } return make_pair(end(), false); // make compiler happy } virtual bool preErase(const key_type&) { return true; } size_type erase(const key_type& x) { if(preErase(x) { return _M_t.erase(x); } return 0; // make compiler happy } The preInsert and preErase methods are virtual Hook Methods, and derived classes override these to add behavior to the (non-virtual) insert and erase functions.. Another nice addition to this map view would be a const _Tp& operator[](const key_type& k) const function, implemented something like this: const _Tp& operator[](const key_type& k) const { const_iterator i = lower_bound(k); if(i == end() || key_comp(k, (*i).first)) // if i->first is >= k throw SearchError(k); return (*i).second; } * Note: this simple implementation assumes that the key can be converted to a string in the constructor of the SearchError exception object. I have at least three Manager-like (Mediator) classes that can use this pattern (i.e., derived from this Map View class) as well as others that need a vector view with a similar filtered design... ---------------------------------------------- Gary > If you are asking me to write this code, well I'm not likely to get around to it. However I'd be glad to review it as an addition to the library. We generally stayed with the STL model of no virtual functions. In the meantime you might like to look at the Iterator Adaptor library and generate your own special view container. -Gary-

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Re: [BGL] Interest in a random-path algorithm.
by Cromwell Enage 11 Feb '04

11 Feb '04

Oh, yeah, I forgot to mention you could use the random path algorithm, too. And thanks for the credit! Cromwell Enage __________________________________ Do you Yahoo!? Yahoo! Finance: Get your refund fast by filing online. http://taxes.yahoo.com/filing.html

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RE: [boost] Perfect Forwarding (almost)
by Powell, Gary 11 Feb '04

11 Feb '04

Just because I like this sort of stuff, I added a test case with 1 level of inheritence, and it works pretty well. There is a minor amount of trickiness to get the derived class to call the right base class constructor. Just need to remember to use the ref.p. All in all I like it better than the MOJO soln which IMO was much more invasive. (I still like the core soln of adding && to indicate you are taking a move reference though, seems to be less error prone to code IMHO.) tested only on gcc 3.22 (2.93 fails miserably.) Anyway "cool" Dave! Yours, -Gary-

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RE: [boost] Re: future of boost.threads
by Glen Knowles 11 Feb '04

11 Feb '04

From: David Abrahams [mailto:dave@boost-consulting.com] >> Of course you cannot portably pass all exceptions, but you may be able >> to pass all the ones that use standard types. > >And what if the std library or somebody else throws exceptions >*derived* from the standard types? If it is not a recognized corba exception what the ACE TAO does is eat it with a catch(...) and then throws a corba system exception on the other side. Glen

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Boost.Python proposed patch 1.31.0
by John Gerschwitz 11 Feb '04

11 Feb '04

It would appear numeric.cpp has some () missing. This means calls to functions such as nelements fail. The text "isaligned" replaced with "iscontiguous" in iscontiguous call. John Gerschwitz *** numeric.cpp.orig 2004-02-11 10:57:50.000000000 +1000 --- numeric.cpp 2004-02-11 11:00:33.000000000 +1000 *************** *** 226,247 **** bool array_base::isaligned() const { ! return extract<bool>(attr("isaligned")); } bool array_base::iscontiguous() const { ! return extract<bool>(attr("isaligned")); } long array_base::itemsize() const { ! return extract<long>(attr("itemsize")); } long array_base::nelements() const { ! return extract<long>(attr("nelements")); } object array_base::nonzero() const --- 226,247 ---- bool array_base::isaligned() const { ! return extract<bool>(attr("isaligned")()); } bool array_base::iscontiguous() const { ! return extract<bool>(attr("iscontiguous")()); } long array_base::itemsize() const { ! return extract<long>(attr("itemsize")()); } long array_base::nelements() const { ! return extract<long>(attr("nelements")()); } object array_base::nonzero() const

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Re: [boost] Is anyone interested in dynamic multi array libarray
by RGProlog＠aol.com 11 Feb '04

11 Feb '04

Wrote garcia(a)cs.indiana.edu >Greetings, >I am trying to grok what it is you describe, but I am afraid I may be >missing something. Could you explain in what ways >dynamic_multi_array >differs from the arrays in the Boost.MultiArray library? >Thanks Thank you for your interest. The dynamic_multi_array arrays differ from the the arrays in the Boost.MultiArray library in the same way the arrays in the Boost.Dynamic Bitset library differ from the arrays in the std::bitset library; it is dynamic vs. static. Thus the rationale behind the Dynamic Multi Array library is similar to the rationale behind Boost.Dynamic Bitset library. It complimemts the Boost.MultiArray library. The way the Dynamic Multi Array library is implemented is different. The relationship between the components of the Dynamic Myltiarray library, for example, is different. While the coupling between multi_array and multi_array_ref the Boost.Dynamic Bitset library is almost the stongest possible, public inheritance, the relationship between dynamic_multi_array & dynamic_multi_array_ref is the weakest possible. The dynamic_multi_array_ref points to the data initialized and managed by the dynamic_multi_array and that's it. (for the details see documentation once it will become available on the vault.) There is a clear rationale behind this decision. The dynamic_multi_array component does not provide the capacity to hone in on its subviews; the dynamic_multi_array and the dynamic_subarray components do. The dynamic_multi_array is stricly an extension of std::vector into the multi dimensional enviroment. Thus a user who needs just that --- a strict extension of std::vector --- and wants to avoid the performance penalty the subview capacity would incur, he/she can use the the dynamic_multi_array component of the library alone. For those who want it all, though, the rest of the components will do the job. Also, the Dynamic Multi Array library does not define a subview type. Instead, at a meager price of a few numeric assignment, an existing dynamic_multi_array_ref object can be parametrized to act as any subview of the same dimension of the array object it references, and still retain its iterator interface. Also, the Dynamic Multi Array library does not define an analog of the Boost.MultiArray library index_gen facility. In analogy to std::vector whose objects can be both accessed and generated using a single integral type, the dynamic_multi_array object can be constructed and accessed using C++ arrays, boost::arrays, std::vector arrays or any other class that contains a contiguous block of integral data and has a random access interface. I did e-mail to you, and will e-mailt to anyone expressing interest in the Dynamic Multi Array library the library's code untill the day I will be able to put the code on the wault. ---Roman

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Three questions about the new license
by Gennaro Prota 11 Feb '04

11 Feb '04

Sorry, if this has already been discussed before, but a) the new license text says: "The copyright notices in the Software and this entire statement, including the above license grant, this restriction and the following disclaimer, must be included in all copies of the Software". IIUC, "the Software" (with a capital 's') includes documentation. Am I right? b) IIUC again, the comments we are inserting into source files // Use, modification and distribution are subject to the // Boost Software License, Version 1.0. (See accompanying file // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) are unnecessarily verbose (and potentially dangerous). One could simply say // Subject to the Boost Software License, Version 1.0. (See etc. etc.) That avoids repeating "use, modification and redistribution" which I'm not sure is everything one can do with the Software (I see for instance, that the license talks about "use, *reproduce*, *display*, distribute, execute, and transmit"). Are, legally speaking, "display" and "reproduce" something different from "use"? c) Suppose one wants to redistribute documentation only (for instance, documentation for one library). Is that allowed? The license seems to say that the docs can only _accompany_ the software (with a lowercase 's'). Genny.

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Python 2.3
by Sebastian Henriksen 11 Feb '04

11 Feb '04

I cannot seem to get Boost.Python properly working with version 2.3. I define the root directory correctly, and the version as 2.3 but vc7.1 tries to link to python22.lib instead of python23.lib. How can I solve this? Thanks... --------------------------------- Do you Yahoo!? Yahoo! Finance: Get your refund fast by filing online

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Questions about the new license
by Powell, Gary 11 Feb '04

11 Feb '04

I know this is pretty late in the process but also have a couple of questions: #1 I'd prefer that any software I contribute to boost remain "free", as in I don't want someone to add 20 lines of code to a library and then sell it. You can sell the compiled machine code but not the original or the modified source other than to cover duplication and distribution costs. #2 I have worked for a overly restrictive employer who was paranoid that anything anyone might do on their own time might be owned by the employee and not the employee. It would be extremely helpful if the license states clearly that derivatives cannot be owned. I'm all for a company like "Boost Consulting", I think they add plenty of value to the boost community and give back way more than they take from the free software. However greedy companies have been known to take free software, modify it and not return it to the public domain. There of course is no time limit and no way to prevent this from happening but it would be better if the copyright was a copy left. Also all that bit about the liability disclaimers, forget it, you can be sued for anything, at anytime, not withstanding the claim about the liability, it might as well not be there for all the good it will do us. On the other hand it does give us a leg up in the event of a lawsuit, "We claimed it was worthless your honor." Also one should be able to write a book about boost, use part of the documentation without a heap of trouble. But a bound reprint of the documentation is owned by???? In general I support this effort. Perhaps some clarifying statements in the FAQ would be enough to calm my fears. -Gary-

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Copyright on bigint in sandbox
by Richard Peters 11 Feb '04

11 Feb '04

Hello, I'm working on a big integer library, and for outputting the value of the integer to a stream I would like to use the code in the bigint library in the sandbox. Unfortunately, the file containing the code (bigint.hpp) hasn't got a copyright notice. Could I have permission to use that code in my own big integer library? For what it's worth, I'm planning to submit my big integer library to boost eventually. thanks, Richard Peters

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