June 2008 - Boost-users - lists.preview.boost.org

a problem with interprocess::managed_windows_shared_memory
by Alex 06 Jun '08

06 Jun '08

Hello, in my program a shared memory object is created by: managed_windows_shared_memory shm (open_or_create, "MySharedMemory", shm_size); The problem is that calling to 'shm' object methods, the program cannot detect - was shared memory actually created or it was opened only? Looks like somewhere inside 'managed_windows_shared_memory' class this information is availble but not exposed via its public interface. May it be fixed? Regards, Alex

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[Boost.StringAlgo] How to insert substr into str
by Valentine Rozental 06 Jun '08

06 Jun '08

Dear All, what is the elegant/right way to insert some substr into the given str? For example: // ------------------------------------------------------- ... std::string str("xyz_123_abc_xyyz_a1b"); std::string mark("abc"); std::string substr("$$$"); iterator_range<range_iterator<std::string>::type> it1 = boost::find_first(str, mark); ... // ------------------------------------------------------- I want to insert substr ("$$$") after mark ("abc") if the mark exists in the str. That is, the result in the example above should be: "xyz_123_abc$$$_xyyz_a1b" Thank you in advance!

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How to simplify repetetive constructor calls?
by Zeljko Vrba 06 Jun '08

06 Jun '08

I have a following situation: class X { type1 v1; type2 v2; ... typen vn; other_var ... public: X() : v1(this), v2(this), .., vn(this), other_var(1, 2, 3) { } }; I'm looking for suggestions on how to automatically initialize variables v1..vn with "this" being passed as the only argument to their constructor. In the ideal case, the programmer should not need to specify any constructor calls for v1..vn, so that the end result looks something like: class X { type1 v1; ... typen vn; other_var; public: X() : other_var(1, 2, 3) { // some "magic" arranges that v1(this) .. vn(this) is called } }; Thanks!

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resize() in boost/multi_array.hpp
by Eric Darve 05 Jun '08

05 Jun '08

Hi, I found what I think is a bug in boost/multi_array.hpp. Perhaps some of you can explain what is wrong. Look at the code below. When executed you get the following error: multi_array_ref.hpp:487: failed assertion `std::equal(other.shape(),other.shape()+this->num_dimensions(), this->shape())' This is caused by the line x.resize(extents[n+1][3]); It seems to me that the code is correct and should work properly. Curiously if one adds x[i][j].resize(extents[0][0]); before x.resize(extents[n+1][3]), the error message disappears. I also added another piece of code at the end showing that if one replaces multi_array< multi_array<int,2>, 2> x; by multi_array< vector<int>, 2> y; then the resize seems to work. The code was run on MacOSX with g++. Eric #include "boost/multi_array.hpp" #include <vector> using boost::multi_array; using boost::extents; using std::vector; int main(void) { const int n = 10; multi_array< multi_array<int,2>, 2> x; x.resize(extents[n][3]); for (int i=0;i<n;++i) { for (int j=0;j<3;++j) { x[i][j].resize(extents[i+1][2]); // Size varies with i } } for (int i=0;i<n;++i) { for (int j=0;j<3;++j) { // x[i][j].resize(extents[0][0]); /* failed assertion below disappears if line above is un-commented */ } } x.resize(extents[n+1][3]); /* Failed assertion when executing line above: multi_array_ref.hpp:487: failed assertion `std::equal(other.shape(),other.shape()+this->num_dimensions(), this->shape())' */ // Attempting a similar operation using vector<int> this time multi_array< vector<int>, 2> y; y.resize(extents[n][3]); for (int i=0;i<n;++i) { for (int j=0;j<3;++j) { y[i][j].resize(i+1); } } y.resize(extents[n+1][3]); /* This instruction executes fine */ return 0; }

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build times and Boost.MultiIndex
by gast128 05 Jun '08

05 Jun '08

Dear all, just refactored a component in our (large) application with use of Boost.MultiIndex. However using a test application it seems that by only including the Boost.MultiIndex header in the header files, the build time is 7 times (700%) slower than without that header file. Pulling Boost.MultiIndex to the cpp file is no option, because I need to export the iterator as well. Of course I can make a wrapper around the iterator as well (for the sole purpose to shield the inclusion of the Boost.MultiIndex header), but isn't this a little bit strange? Putting Boost.MultiIndex in the pch is also a no-op because, 1) every pch must be adjusted, 2) VC++ 7.1 chokes on that. It is not something Boost can do much about it, but it as least an irritating point to put it mildly. It greatly cost productive hours to wait for builds to finish. Something for the c++ committee? c# seems to have a superior build system... wkr, me

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Reader/Writer Mutex
by Selçuk Giray Özdamar 05 Jun '08

05 Jun '08

Hi everyone, Below you can see my simple thread safe class which allows multiple readers and exclusive write for single writer. Is this boost implementation correct? Also if anyone has other aspects, I'm open. Regards... typedef boost::shared_mutex ReadWriteMutex; typedef boost::shared_lock<boost::shared_mutex> ReadLock; typedef boost::unique_lock<boost::shared_mutex> WriteLock; class MtClass { public: MtClass() : m_value() { } ~MtClass(){} void setValue(int value) { WriteLock w_lock(rw_mutex); m_value = value; } int getValue(void) const { ReadLock r_lock(rw_mutex); return m_value; } private: int m_value; mutable ReadWriteMutex rw_mutex; };

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Where is Math Toolkit in the Boost Vault?
by John Maddock 05 Jun '08

05 Jun '08

Boris wrote: > Can anyone provide me a link to download the Math Toolkit? If I > remember correctly it could be found in the Boost Vault before (but I > can't find it anymore). I know that it's shipped now with Boost > 1.36.0 but I can't upgrade to the latest version. The version in the vault was outdated so I removed it once it shipped as a released Boost version. What I suggest you do is grab a copy of boost/math and libs/math from the 1.36 release and use those. I'm fairly sure (!) that should work OK with 1.35.1. HTH, John.

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boost documentation in printable format
by e r 05 Jun '08

05 Jun '08

Hi, I'd like to print an entire boost library documentation. Is there a convenient way to do it? Thanks, E.

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Using Boost.Test in a dynamically loaded library
by Florian Winter 05 Jun '08

05 Jun '08

We are trying to write units tests using the Boost.test framework which involve dynamic loading of libraries (i.e. lt_dlopen on Linux or LoadLibrary on Windows) and doing tests using the Boost test tools in code inside the dynamically loaded library. Does Boost.Test support this? We have run into problems when trying to use the quick-and-dirty "include" option for defining the Boost.Test symbols. Dynamically loaded libraries may not contain undefined symbols, and including the implementation headers such as <boost/test/included/unit_test.hpp> in both the dynamically loaded library and the main application seems to lead to duplicate symbols. In particular, if we use BOOST_CHECK macros in both the main application, everything works fine. However, if we use BOOST_CHECK macros in the dynamically loaded library, we get an exception with the following comment: can't use testing tools before framework is initialized We suspect that this is caused by Boost.Test global symbols being defined multiple times - once in the application and once in the dynamic library. We would like to know what is the "best" practice to use Boost.Test in unit tests that require dynamic loading of libraries and tests being made in both application code and dynamic library code. It must work on Linux (using libraries created with libtool and libltdl for dynamic loading) and Windows (using DLLs and LoadLibrary for dynamic loading). Is this even possible and has it been tested before? Would using a static or shared library version of Boost.Test solve our problem? Are there any other potential pitfalls that we should be aware of? Thanks in advance for your help. Best Regards, Florian Winter, Motama GmbH -- Florian Winter Software-Entwickler

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[serialization] reverse bytes in portable_binary_oarchive
by Chris Weed 04 Jun '08

04 Jun '08

I am a little confused by the section of code in the ifdef of portable_binary_oarchive 48 #ifdef BOOST_BIG_ENDIAN 49 cptr += (sizeof(boost::intmax_t) - size); 50 if(m_flags & endian_big) 51 reverse_bytes(size, cptr); 52 #else 53 if(m_flags & endian_big) 54 reverse_bytes(size, cptr); 55 #endif I would expect line 50 to be if(m_flags & endian_little) Chris

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