October 2008 - Boost-users - lists.boost.org

[Proto] Extracting types of sub-expression in transform
by Ivan Godard 20 Oct '08

20 Oct '08

Various comments: http://en.wikipedia.org/wiki/Algol68: I don't see any discussion there of van Wijngaarden grammars, or even anything that is recognizable as a formal grammar. What am I supposed to be looking at on that page? The Wikipedia Algol68 article is a reasonable brief informal introduction. It does not mention VWG; I cited it so you could see what VWG was used to define, and so you would have a more congenial starting point than the Algol68 definition itself. http://burks.brighton.ac.uk/burks/language/other/a68rr/rrtoc.htm I see a large table of contents there. Care to narrow it down for me? This citation is the formal definition. The discussion of the definition mechanism is chapter 1. Chapters 2-9 are the language proper; 10-11 are what a modern language would call the "standard library" and in this context can be ignored; and 12 is tabular summary material that appears to have been omitted from the document. The whole report is <10% the size of of the C++ standard /without/ its standard library, and for a richer language than C++ at that. In consequence the definition is extremely dense semantically. For example, Algol68 permits slicing (a generalization of subscripting) a multidimensional array so that the result is an array of the same or less dimension that is a regular partial alias of the original. For example, given a rectangular matrix you can apply a slicing operation that yields the tridiagonal of the original, which then can be manipulated as an array in its own right. The /whole /formal definition of this capability (including syntax, type and semantic definition) is this gem in VWG (from 5.3.2.1 in the cite): a) *REFETY MODE1 NEST slice*{5D <http://burks.brighton.ac.uk/burks/language/other/a68rr/rr5.htm#51D> } * : weak REFLEXETY ROWS1 of MODE1 NEST PRIMARY*{5D <http://burks.brighton.ac.uk/burks/language/other/a68rr/rr5.htm#51D> } *, ROWS1 leaving EMPTY NEST indexer*{b,c,-}* STYLE bracket, where (REFETY) is derived from (REFLEXETY)*{531b,c <http://burks.brighton.ac.uk/burks/language/other/a68rr/rr53.htm#5311b> ,-}*; where (MODE1) is (ROWS2 of MODE2), weak REFLEXETY ROWS1 of MODE2 NEST PRIMARY*{5D <http://burks.brighton.ac.uk/burks/language/other/a68rr/rr5.htm#51D> } *, ROWS1 leaving ROWS2 NEST indexer*{b,d,-}* STYLE bracket, where (REFETY) is derived from (REFLEXETY)*{531b,c <http://burks.brighton.ac.uk/burks/language/other/a68rr/rr53.htm#5311b> ,-}*. * The rest of the section comprises a few non-terminal definitions that are used in the above, examples of each production rule, and a (perhaps) helpful narrative comment to explain the lot: {A *subscript* decreases the number of dimensions by one, but a *trimmer* leaves it unchanged. In rule a, *'ROWS1'* reflects the number of *trimscripts* in the *slice*, and *'ROWS2'* the number of these which are *trimmers* or *revised-lower-bound-options*. If the value to be sliced is a name, then the yield of the *slice* is also a name. Moreover, if the mode of the former name is *'reference to flexible ROWS1 of MODE'*, then that yield is a transient name (see 2.1.3.6.c <http://burks.brighton.ac.uk/burks/language/other/a68rr/rr213.htm#2136c> ).} Note that Algol68 dates from the days when Fortran II was the preeminent language for such things; C did not exist; object orientation was known only in an obscure simulation language; and even the notion of structured programming was not yet fully worked out. If you really want to pursue this then I strongly recommend that you start with Lindsey & van der Meulen (Lindsey, C.H. and van der Meulen, S.G., /Informal Introduction to ALGOL 68/, North-Holland, 1971). It is well written and clear, and you will know far more about language design and definition than perhaps you really wanted when you have finished it. As for my own contribution: How badly do you want to see something like this in Boost? Badly enough to jump in and get your hands dirty with some code? Maybe you could help me to add two-level grammar support to Proto. the answer is not badly enough to do it myself, and you (or anyone) have /much /to do even before deciding to actually try. Yes, I'll help, but I have no capacity to hand-hold. However, by all means jump in: Well, is there room for *yet another guy* in this stuff cause I'm really interested to get somethign out of this. However, the boost list is probably not the right place. You can reach me directly through /ivan at ootbcomp dot com/. Google has a lot on both Algol68 and van Wijngaarden grammars. Have fun :-) Ivan

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Boost Graph Layout with Fixed Nodes
by Donovan Parks 20 Oct '08

20 Oct '08

Hello, I wish to layout a graph using a force-directed layout algorithm, but where a few of the nodes are fixed. That is, there is a subset of nodes that have a predetermined position that must be maintained. Is it possible to achieve such behavior using one of the boost graph layout algorithms? I have been over the documentation for each and my conclusion would be that such behavior is not possible. Has anyone tried this before? Can anyone point me to some resources that aim to achieve this sort of layout? Any and all suggestions welcomed. Thanks. Regards, Donovan

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Can not compile a program that uses typeof, package by gcc?
by Ivan Godard 20 Oct '08

20 Oct '08

Peng asked: Can somebody let me know if the following code can be compiled by a more recent version of gcc or some other compiler? The gcc folks themselves use the EDG front end to check bug reports against gcc/g++. The EDG front end is used by Intel's ICC compiler and many others. There is a great online service through which you can try your code against this compiler: http://www.comeaucomputing.com/tryitout/ I heavily use this Comeau service, not only for actual gcc bugs (I've reported a ton) but also to make progress when the bug is between my ears and gcc is not being helpful. The EDG diagnostic quality is way beyond gcc - they even do a better job of the cryptic error message stacks from template metaprogramming. Ivan

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counting semaphore boost 1.36
by gali barabash 20 Oct '08

20 Oct '08

Hello, I would like to use a counting semaphore - and to make sure that the threads will enter the semaphore by their arrival order. Is there a build-in counting semaphore with some kind of priority queue? if not, do boost threads have some kind of priority? I've noticed that some people implemented counting semaphore with condition variable, using wait and notify, but that doesn't keep the order. Is there another way to do it without actually implement my own priority queue? Thanks in advance, Gali

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Re: [Boost-users] [Proto] Extracting types of sub-expression in transform
by Ivan Godard 20 Oct '08

20 Oct '08

Eric Niebler wrote: I hadn't even considered the notion of a type system for a DSEL, but it makes perfect sense. Unfortunately, the only tutorial I found for van Wijngaarden grammars is here: http://homepages.cwi.nl/~steven/vw.html Perhaps it's because I'm tired, but I'm not making heads or tails of it at the moment. Can you point me to a gentler introduction? (Way back when I started with expression templates, I thought that calling them an "embedded language" was just a cute metaphor, but much can be gained from taking the serious view that these really *are* languages, deserving of grammars, semantic actions, ... type systems, too. Once we fully embrace that view, there's decades worth of programming language theory we can leverage.) and: Joel Falcou wrote: Eric Niebler a ?crit : > > (Way back when I started with expression templates, I thought that > > calling them an "embedded language" was just a cute metaphor, but much > > can be gained from taking the serious view that these really *are* > > languages, deserving of grammars, semantic actions, ... type systems, > > too. Once we fully embrace that view, there's decades worth of > > programming language theory we can leverage.) > > > You just have described parts of my research plans ;) My current work try to get a way using ET and Concept in C++ to have a condensed way to describe operationnal and/or denotanionnal semantic for C++ DSEL. Guess I'll indeed have to swallow up this typing system rules myself. Ivan : Thanks for the references. VWG was invented for and used to define Algol68. Personally, I find it easiest to understand a formal system when I have a worked out example in front of me. If you're the same way, I suggest starting with: http://en.wikipedia.org/wiki/Algol68 http://burks.brighton.ac.uk/burks/language/other/a68rr/rrtoc.htm Lindsey, C.H. and van der Meulen, S.G., /Informal Introduction to ALGOL 68/, North-Holland, 1971 (also sometimes known as "Algol68 without Tears") I'm biased here - I was on the working group that produced the second reference above - but I think that the only way to introduce semantics into a practical and general DSEL system is via formal means. However, both VWG and its exemplar in Algol68 have a very high intellectual tractability barrier, akin to the barrier facing newcomers to Functional Programming or Metaprogramming. But a casual note in Boost has already turned up three people who at least see the problem. That's a start :-) Ivan

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A question about boost::asio (using boost 1.36 minGW eclipse CDT windows
by gali barabash 20 Oct '08

20 Oct '08

Hello, I have compilation problem when trying to just #include <boost/asio.hpp>: /src/timer.o: In function `ZNK5boost16exception_detail15exception_cloneINS0_19error_info_injectorINS_6system12system_errorEEEE7add_refEv': C:/Dev/MessageThreads/Debug/../src/timer.cpp:(.text$_ZN5boost4asio6detail12winsock_initILi2ELi0EE7do_initD1Ev[boost::asio::detail::winsock_init<2, 0>::do_init::~do_init()]+0x7): undefined reference to `WSACleanup@0' C:/Dev/MessageThreads/Debug/../src/timer.cpp:(.text$_ZN5boost4asio6detail12winsock_initILi2ELi0EE7do_initC1Ev[boost::asio::detail::winsock_init<2, 0>::do_init::do_init()]+0x1f): undefined reference to `WSAStartup@8' collect2: ld returned 1 exit status I linked boost system boost_system-mgw34-mt-d-1_36 in Eclipse (MinGW C++ linker). Can someone please tell me what is wrong? Thanks a lot! Gali.

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Boost [Asio] Problem with POST Request and async_read
by anti00Zero 20 Oct '08

20 Oct '08

Hello. I've wrote a SSL Proxy and have a big problem. I use a HTTP Client in bei Proxy to communicate with my HTTP Server. HTTP Client and HTTP Server are localhost. A SSL Browser should call my local SSL Proxy and internal a HTTP Client communicate with my HTTP Server. If the SSL Brower sends a POST request to my proxy, I have a problem. This is my code: async_write(m_HTTPSocket, buffer(m_sSSLRequestBuffer), transfer_at_least(1), boost::bind(&CSession::HandleHTTPWriteRequest, this, placeholders::error)); void CSession::HandleHTTPWriteRequest(const error_code& error) { if (!error) { async_read(m_HTTPSocket, buffer(m_HTTPResponse, MAX_HTTPRESPONSE_BUFFER_LENGTH), transfer_at_least(1), boost::bind(&CSession::HandleHTTPReadResponse, this, placeholders::error, placeholders::bytes_transferred)); } else if(error != error::eof) { SendErrorToSSL(error); } } void CSession::HandleHTTPReadResponse(const error_code& error, size_t iTransferredBytes) { if(!error) { The error is boost::asio::error::connection_aborted (10053 (WSAECONNABORTED)). If I don't use my SSL Proxy the HTTP Browser works correct. I use Visual Studio 2005 with Boost 1.36 Thanks for help. -- Psssst! Schon vom neuen GMX MultiMessenger gehört? Der kann`s mit allen: http://www.gmx.net/de/go/multimessenger

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should i delete the *.o files?
by control_batik 20 Oct '08

20 Oct '08

Hi all, I recently compiled boost_ 1.36,(after 4 hours....). My question is simple (I haven't so much experience with C++ ), I only need the dll and .lib files, right?, because my build directory contains also the *.o files , and it sums 17 gb in my disk, and I think it's too much. Can i erase the *.o files??? Thanks for your answer. -- View this message in context: http://www.nabble.com/should-i-delete-the-*.o-files--tp20053058p20053058.ht… Sent from the Boost - Users mailing list archive at Nabble.com.

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Re: [Boost-users] Visual Studio 9.0 Express & boost 1.36 linker issues
by BenBe 20 Oct '08

20 Oct '08

Hi! I have exactly the same problem with the same error messages. Has somebody find out how to solve it? How can i build the lib sources with the settings of my project? - BenBe -- View this message in context: http://www.nabble.com/Visual-Studio-9.0-Express---boost-1.36-linker-issues-… Sent from the Boost - Users mailing list archive at Nabble.com.

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thread pool
by Migunov Andrey 20 Oct '08

20 Oct '08

Hi! I need to use a thread's pool in my program. There is no way to do it with boost::thread of current release. I found some libraries, but i don't know how quality is it. Please, advise me a good thread's pool library that is compatible with boost. best regards

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