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MPL ?
by Toon Knapen 01 May '02

01 May '02

Inside a templated class, I need to provide two different implementations for a function based on the compile-time decision ::boost::is_convertible< value_type,double >::value. How can I do this using MPL ? thanks, toon

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RE: [Boost-Users] shared_ptr and incomplete types
by bjorn.karlsson＠readsoft.com 01 May '02

01 May '02

> From: Jim Hyslop [mailto:jim.hyslop@leitch.com] > > I notice that the implementation available at boost.org does not allow > the single-argument ctor to be called on an incomplete type, e.g.: [snip] > The documentation on the single-argument ctor, though, does not state > that T must be a complete type. Is the implementation > stricter than the > documentation, or is the documentation incomplete? I believe that the implementation is correct, and that belief is confirmed by the latest documentation in the CVS - T must indeed be a complete type. Another change is the addition of a default constructor, which does not require T to be complete. > I'm writing an article on the smart pointers for the CUJ, and I'd like Cool! ;-) > to know if I can correctly state "The default behavior for > shared_ptr is > to require complete types. You can, however, manage an incomplete type > if you provide a function or function object, which will be > called when > the owned object is destroyed." Since shared_ptr requires a complete type only for a few operations, such as the constructor that you mentioned, and reset(T * p), I'd rephrase to something more explicit, like: "The instantiation of a shared_ptr typically requires a complete type. [etc]". Bjorn Karlsson [Non-text portions of this message have been removed]

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shared_ptr and incomplete types
by Jim Hyslop 01 May '02

01 May '02

The documentation at http://www.boost.org/libs/smart_ptr/shared_ptr.htm states that "T may be void, but in that case, either an explicit delete function must be passed in, or the pointed-to object must have a trivial destructor." I notice that the implementation available at boost.org does not allow the single-argument ctor to be called on an incomplete type, e.g.: class simple; simple * createSimple(); shared_ptr<simple> simpleFactory() { return shared_ptr<simple>(createSimple()); } The documentation on the single-argument ctor, though, does not state that T must be a complete type. Is the implementation stricter than the documentation, or is the documentation incomplete? I'm writing an article on the smart pointers for the CUJ, and I'd like to know if I can correctly state "The default behavior for shared_ptr is to require complete types. You can, however, manage an incomplete type if you provide a function or function object, which will be called when the owned object is destroyed." -- Jim

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Graph Library - AllExamples.dsw, anyone got it?
by loopylozzysdad 30 Apr '02

30 Apr '02

Hi All, Just read the excellent Boost Graph Library book. The AllExamples.dsw file is not on the accompanying CD. In the Errata web page (http://siek.info/bgl.html) it says... "On the accompanying CD, the file \BGL\VC++ Projects\AllExamples.dsw is missing. You can download the missing file from here BGLVCprojects.tgz." The file there is a .dsw file but it is NOT the missing one. Has anyone got the real thing? All the best and thanks - Richard Howells

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Re: Boost.Thread (VC specific)
by Holger Thiele 30 Apr '02

30 Apr '02

>-----Ursprungliche Nachricht----- >Von: bill_kempf [mailto:williamkempf@hotmail.com] >Gesendet: Dienstag, 30. April 2002 17:54 >An: Boost-Users(a)yahoogroups.com >Betreff: [Boost-Users] Re: Boost.Thread (VC specific) > > >I don't agree. If it's a good idea, then I'd expect MS to do this by >default for IDE generated builds. Such as default warning level 3? >There's some overhead involved in >generating this, there's compile time overhead (which is important to >some) Do you have figures on that? In my experience, this overhead seems to be a small price to pay for the ability to track bugs (inside your debugger!) on released code. >and there's the fact that many users will be confused by the >presence of debug information and why "stepping" through the code >behaves so strangely and unpredictably. As always, if someone doesn't know what he's doing, there's little help besides getting educated. But, seriously, I think that most users that even get into debugging release builds would surely appreciate library code that supports this. Just my 2 cents. Cheers, and thanks for one of my favorite libraries Holger Thiele D.A.V.I.D. GmbH www.david-gmbh.de

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RE: [Boost-Users] operator == in shared_ptr
by bjorn.karlsson＠readsoft.com 30 Apr '02

30 Apr '02

> From: sashan [mailto:sashang@ihug.co.nz] [snip] > Is there a better way that doesn't involve 1) having to write > a wrapper class around a basic type (or any type) and 2) > doesn't involve changing the shared_ptr::operator==. > As others have pointed out, the solution is to use a function object and std::find_if. In this case, the comparison doesn't even need a separate predicate - the (exceptionally cool) Boost.Bind library can be used instead: vector<shared_ptr<int> >::iterator it=std::find_if(vec.begin(),vec.end(),bind(std::equal_to<int>(),bind(&shared _ptr<int>::operator*, _1),42)); Bjorn Karlsson [Non-text portions of this message have been removed]

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operator == in shared_ptr
by sashan 30 Apr '02

30 Apr '02

Hi Because the operator== function compares pointers and not what they're pointing to this is what I've had to do to get it to find an integer. Basically I had to wrap the basic int type within another class called Int, as show below. class Int { private: shared_ptr<int> p; public: Int(int i) {p.reset(new int); *p = i;} bool operator==(const Int& r) {return *p.get() == *r.p.get();} ~Int() {}; }; void main() { vector < Int > vec; vec.push_back(Int(1)); vec.push_back(Int(2)); vec.push_back(Int(3)); Int p(4); if (find(vec.begin(), vec.end(), p) == vec.end()) { cout << "Couldn't find it"; } } Is there a better way that doesn't involve 1) having to write a wrapper class around a basic type (or any type) and 2) doesn't involve changing the shared_ptr::operator==. [Non-text portions of this message have been removed]

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boost::function::set()
by Douglas Gregor 29 Apr '02

29 Apr '02

Does anyone use the boost::function::set() methods? I'd like to remove them for Boost.Function v2 to cut down on the size of the interface. If you are using set() and would like to keep using it, please tell me. Doug

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RE: [Boost-Users] iterating over a tuple
by Aleksey Gurtovoy 29 Apr '02

29 Apr '02

Toon Knapen wrote: > On Friday 26 April 2002 13:37, Aleksey Gurtovoy wrote: > > Toon Knapen wrote: > > > I have a list of heterogeneous objects, e.g. > [snip sample code] > > > > And now I want to have a function that can accumulate the > > > value sof all the objects in the tuple, e.g. (pseudocode since > > > my problem is exacly that I can't figure out how to code this) > > > > > > template < typename TypleType > > > > int accumulate_values(const TupleType& t) > > > { > > > int acc = 0; > > > for(int i = 0 ; i < t.size() ; ++i ) acc += (get< i >( > t )).value(); > > > } > > > > > > Can I do this using mpl (mpl looks great but I can't figure > > > out how to do this). > > > > It's not exactly a part of MPL (the library doesn't target > "run-time" stuff > > to that extent yet; I hope it will some day), but "tuple extension" > > components I wrote some time ago > > > (http://groups.yahoo.com/group/boost/files/tuple_ext/tuple_ext-08-nov-01.zip ) > allow one to do exactly these kinds of things: > [snip aleksey's solution] > > Thanks, I like tuple_ext a _lot_ ! I am glad you found it useful. > It would be great to have complete STL-like functionality like this. Yep. The only problem with this is that we are going to end up with 3 STL-like libraries within the same language :) (the original one ("run-time"), the MPL one (pure compile time), and something in between, - HSTL (Heterogeneous Sequences Template Library :)). All three with the same algorithms, just written in different notation :). Emily's heterogeneous lists (www.oonumerics.org/tmpw01/winch.pdf, http://groups.yahoo.com/group/boost/files/alist-feb14-02.zip) 'tuple_ext' components, and MPL's v.2 half-run-time 'for_each' are obviously hanging around that "in between" thing. > Plans on adding this tuple_ext to the CVS ? Some; I think it should be a full-fledged submission that would take the prior art and build a simple framework on it. It's not a large undertaking, though - most of the concepts and some code are already here :). Aleksey

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BGL: "Supergraphs?"
by David A. Greene 29 Apr '02

29 Apr '02

Hi, I've been learning the BGL and porting some existing code over to it. First off, Kudos to Jeremy, Lie-Quan and all the BGL developers. This library is great! I find the filtered_graph potentially very useful for my application except for one case. In some (not rare) instances I need to be able to create a filtered_graph that spans two graphs. In other words, I have two separate graphs. Most of the time the information I need is entirely contained in one graph so a filtered_graph works perfectly. However, sometimes I need to create a filtered_graph from several separate graphs and link them together in a well-defined manner (i.e. I easily know where the edges should go). I need a "supergraph" that is the combination of the two filtered graphs. Right now the application handles this problem by creating a new graph from the existing graphs. But this takes time and memory. I'd like to get rid of this overhead if possible, especially since these are often short-lived graphs. The filtered_graph objects would not be induced subgraphs so a subgraph object wouldn't work (subgraph also doesn't support something that spans multiple graphs anyway). What I need is the opposite of subgraph -- a unified interface to multiple filtered_graphs. This seems very hard to do because each filtered_graph will have its own vertex and edge index mappings. An extra level of indirection would solve the problem but I'm not sure the overhead would be less than simply creating a new graph. Thoughts? Opinions? Thanks again for a great library! -Dave -- "Some little people have music in them, but Fats, he was all music, and you know how big he was." -- James P. Johnson

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Newbie: problems installing under RedHat 7.2
by Benjamin Han 28 Apr '02

28 Apr '02

I'm just trying to install Boost library under RedHat 7.2. I was following the build instructions found on the Boost website, but it seemed to fail for several targets. I'm wondering if it's because RH7.2 uses its version of gcc 2.96. Since my project work needs gcc 3.0+, my question is, what do I need to do in order to use gcc3/g++3 instead of gcc/g++? The build system seems exotic and I just want to get over with the installation asap and start to use the library. (does changing /usr/bin/gcc and /usr/bin/g++ links work?) Here is the build command I tried: jam -sBOOST_ROOT=. -sTOOLS="gcc" Errors (selected): ... libs/thread/build/../src/once.cpp: In function `void boost::call_once (void (*) (), once_flag &)': boost/thread/once.hpp:38: previous declaration of `void boost::call_once (void (*) (), once_flag &)' with C++ linkage libs/thread/build/../src/once.cpp:77: conflicts with new declaration ... MkDir1 libs/python/build/bin/libboost_python_static/gcc/debug/runtime-link-dynam ic/shared-linkable-true gcc-C++-action libs/python/build/bin/libboost_python_static/gcc/debug/runtime-li nk-dynamic/shared-linkable-true/types.o In file included from boost/python/errors.hpp:13, from boost/python/detail/call_object.hpp:8, from libs/python/build/../src/types.cpp:11: boost/python/detail/wrap_python.hpp:24:24: patchlevel.h: No such file or directo ry boost/python/detail/wrap_python.hpp:100:20: Python.h: No such file or directory ... (lots of Python-related errors) ... gcc-C++-action status/bin/is_function_test/gcc/debug/runtime-link-dynamic/is_fun ction_test.o boost/type_traits/function_traits.hpp: In instantiation of `boost::is_function<i nt[]>': status/../libs/type_traits/tests/is_function_test.cpp:68: instantiated from he re boost/type_traits/function_traits.hpp:148: Internal error: Segmentation fault. Please submit a full bug report. See <URL:http://bugzilla.redhat.com/bugzilla/> for instructions. ... &boost::noncopyable::operator= (const boost::noncopyable &)' is private status/../libs/utility/noncopyable_test.cpp:35: within this context ...failed updating 43 targets... ...skipped 24 targets... ...updated 629 targets... The folllowing RPMs are installed on the machine: 1. gcc-2.96-110 2. gcc3-3.1-0.23.1 3. python-1.5.2-38 4. python2-2.2-16 5. glibc-2.2.5-32 6. boost-build-1.0-1 7. boost-jam-3.0-1 Other info: kernel 2.4.18 (manually built) Any comment would be greatly appreciated, Ben

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RE: [Boost-Users] iterating over a tuple
by Aleksey Gurtovoy 28 Apr '02

28 Apr '02

Toon Knapen wrote: > I have a list of heterogeneous objects, e.g. > > struct Foo { > Foo(int v) : value_( v ) {} > int value() const { return value_ ; } > int value_; > }; > > struct Bar { > Bar(int v) : value_( v ) {} > int value() const { return value_ ; } > int value_; > }; > > int main() > { > Foo foo(3); > Bar bar(7); > typedef boost::tuple< Foo, Bar > MyTuple ; > MyTuple my_tuple( foo, bar ); > return 0; > } > > And now I want to have a function that can accumulate the > value sof all the objects in the tuple, e.g. (pseudocode since > my problem is exacly that I can't figure out how to code this) > > template < typename TypleType > > int accumulate_values(const TupleType& t) > { > int acc = 0; > for(int i = 0 ; i < t.size() ; ++i ) acc += (get< i >( t )).value(); > } > > Can I do this using mpl (mpl looks great but I can't figure > out how to do this). It's not exactly a part of MPL (the library doesn't target "run-time" stuff to that extent yet; I hope it will some day), but "tuple extension" components I wrote some time ago (http://groups.yahoo.com/group/boost/files/tuple_ext/tuple_ext-08-nov-01.zip ) allow one to do exactly these kinds of things: // untested! :) template< typename Seq, typename T, typename BinaryOp > T accumulate(Seq const& s, T const& Init, BinaryOp op) { T result = Init; for_each( begin(s) , end(s) , boost::bind<T>(op, boost::ref(result), _1) ); return result; } With the above, you can do something like this: struct get_value { template< typename T > int operator()(T const& x) const { return x.value(); } }; int sum = accumulate( tuple , 0 , boost::bind(std::plus<int>() , _1 , boost::bind<int>(get_value(),_2) ) ); Hope it's not too complicated :). LL might allow to do better on this one. Aleksey

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iterating over a tuple
by Toon Knapen 26 Apr '02

26 Apr '02

I have a list of heterogeneous objects, e.g. struct Foo { Foo(int v) : value_( v ) {} int value() const { return value_ ; } int value_; }; struct Bar { Bar(int v) : value_( v ) {} int value() const { return value_ ; } int value_; }; int main() { Foo foo(3); Bar bar(7); typedef boost::tuple< Foo, Bar > MyTuple ; MyTuple my_tuple( foo, bar ); return 0; } And now I want to have a function that can accumulate the value sof all the objects in the tuple, e.g. (pseudocode since my problem is exacly that I can't figure out how to code this) template < typename TypleType > int accumulate_values(const TupleType& t) { int acc = 0; for(int i = 0 ; i < t.size() ; ++i ) acc += (get< i >( t )).value(); } Can I do this using mpl (mpl looks great but I can't figure out how to do this). thanks, toon

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RE: [Boost-Users] iterating over a tuple
by Aleksey Gurtovoy 26 Apr '02

26 Apr '02

Toon Knapen wrote: > > Hope it's not too complicated :). LL might allow to do > > better on this one. > > Thanks, I'll try it out. Coudl you enlighten me on how to > solve it with the lambda library. I don't see how to iterate over > the different indexes in combination with LL ? Oh, sorry, my last sentence was probably misleading. What I meant is that LL can do a better job on construction of the function object that is passed to tuple's 'accumulate': struct get_value { template< typename T > int operator()(T const& x) const { return x.value(); } }; int sum = accumulate(tuple, 0, _1 + ll::bind(get_value(),_2)); I was also hoping that it could help us to get rid of the ad hoc 'get_value' class, but, thinking about it more, I don't see how :(. HTH, Aleksey

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Redistributing Boost?
by Duane Murphy 26 Apr '02

26 Apr '02

Boost has a reasonably liberal license for use in product both commercial and non-commercial. However I am wondering about redistributing source code. Does the boost license(s?) allow the sources to be redistributed as part of a commercial product? For example, a commericial library or framework that is developed using boost for underlying support and that library is sold in source code form. What are the legalities of distributing boost in this fashion? ...Duane -- "If tyranny and oppression come to this land, it will be in the guise of fighting a foreign enemy." - James Madison

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boost::thread_specific_ptr problem
by svanechel 26 Apr '02

26 Apr '02

Hi there, I've encountered a curious problem when using thread_specific_ptr. We are developing a Win32 Service and for each thread we need an object that stays alive for as long as the thread runs (except for the main thread). So we created a dll and in its DllMain function we did something like this: boost::thread_specific_ptr<SomeClass> someClass; BOOL WINAPI DllMain( HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved ) { switch ( fdwReason ) { case DLL_THREAD_ATTACH: someClass.reset( new SomeClass ); // Breakpoint 1 case DLL_THREAD_DETACH: someClass.reset(); // Breakpoint 2 } } And now comes the curious bit: If you build this dll and implicitly link it with the exe the exe's startup code hangs in GetModuleFileName (). This is the call stack upto that point _setargv (STDARGV.C) __getmainargs (CRTLIB.C) WinMainCRTStartup (CRTEXE.C) At that point the code hasn't reached Breakpoint 1 yet (it's still in the exe's startup code in the main thread and we are not interested in the main thread) It is not the class we are allocating. We tried it with an empty class and that produced the same result. However, if we stored an object in a TLS slot allocated with the API, everything works. It probably has nothing to do with the exe being a service either, since the same dll with linked to a normal exe had the same problems. To complicate matters even further we reached Breakpoint 1 in a number of runs, but as soon as we left DllMain in those instances the application hanged again. If you break then you see from the call stack that the code is running somewhere in NTDll. Are we using thread_specific_ptr in a way that it wasn't meant to be used, or did we encounter a real problem here? I've used thread_specific_ptr before and had no problems then. PS: We develop under Windows 2000 on a Compaq Evo W6000 dual processor machine, using MSVC 6, SP 5 and the 08/2001 version of the platform SDK. The service can run both under the Local System Account or under an account with absolutely no privileges at all. Sven Van Echelpoel

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operator== in the shared_ptr class
by sashan 25 Apr '02

25 Apr '02

Hi Why does the operator == function in the shared_ptr class compare the pointer values and not what they are pointing to? I'm trying to use the find function (in the stl) and I don't know how to get around this. Here's an example. vector <shared_ptr <SomeClass> > vecStuff; shared_ptr<SomeClass> pkToFind(new SomeClass(x,y,z)); if (find(vecStuff.begin(), vecStuff.end(), pkToFind) != vecStuff.end()) { } This didn't work as expected because the shared_ptr class's operator== function does not use SomeClass's operator == function to do the comparison. Instead it compares the pointer values. I don't understand why they made it like this and I don't think they were dumb enough to overlook this so there must be something I'm missing. Thanks Sashan [Non-text portions of this message have been removed]

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Building Boost 1.27.0 for VC7
by Javier Estrada 25 Apr '02

25 Apr '02

I'd like to build boost for VC7. I've followed several of the threads that detail some of the problems that people has faced and the solutions that have been found. Being the first time that I use boost: -How do I get access to a "free" CVS client that I can use on my machine and some information on how to use it? I'm familiar with SourceSafe on Windows platforms and I'm running Windows 2000 at home, Windows XP in my office. - Is it worth it to build 1.27, or should I wait for a "minor point" (1.27.1??) release or should I download the sources and go from there? It seems that there have been several changes made to 1.27.0 to accomodate VC7. Regards, Javier.

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RE: [Boost-Users] crc
by Arjun Bijanki 25 Apr '02

25 Apr '02

GIE wrote: > I have problem compiling following empty project: [code removed] It looks like you must define BOOST_NO_DEPENDENT_TYPES_IN_TEMPLATE_VALUE_PARAMETERS. If I define that, it compiles. Arjun Bijanki Microsoft Corporation

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Boost.Threads lib files
by judoka1981 24 Apr '02

24 Apr '02

[Tried sending this through news://gmane.comp.lib.boost.user a few days ago, but it didn't seem to get through anywhere] Hi, I've started experimenting a bit with Boost.Thread, platform is currently WinXP / VC.NET. Just a question on the generated libraries and their names. Wouldn't it be more convenient to put all resulting .lib files in the same directory, and distinguishing between debug/release versions by name, e.g.: libboost_thread.lib // release libboost_thread_d.lib // debug libboost_threadmon.lib // release threadmon ... etc ... and, when the libraries support static linking of the CRT also: libboost_thread_static.lib libboost_thread_static_d.lib As it is now (Boost 1.27.0), it really is a bit awkward to use. Also, why not put all Boost library files in the same directory (e.g. BOOST_ROOT/lib) during build? Sorry if this topic already has been covered, I've been off the Boost lists for some time now. // Johan

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RE: Common build problems (was: Building Boost 1.27.0 for VC7)
by Jim.Hyslop 24 Apr '02

24 Apr '02

I wrote: > I think if we break it down and everyone scans 30 messages > (the number of messages presented on the web interface) we > can go through the archive pretty quickly. I forgot to mention, I will coordinate this effort - if you want to scan some messages in the archive, email me and I'll let you know which messages to scan. -- Jim

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RE: Common build problems (was: Building Boost 1.27.0 for VC7)
by Jim.Hyslop 24 Apr '02

24 Apr '02

Javier Estrada [mailto:ljestrada@hotmail.com] wrote: > I'd like to build boost for VC7. I've followed several of > the threads that > detail some of the problems that people has faced and the > solutions that have been found. It seems to me that we're seeing the same build problems crop up again and again. I have added a page to the Wiki: http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl?CommonBuildPr oblems where we can build up a list of frequently-encountered problems and how to solve them. So far it's just a skeleton, feel free to add to it, everyone :-) It would be nice if we could review the email archive to add the problems to the Wiki. Slogging through all 600+ messages is a bit of a long haul, but I think if we break it down and everyone scans 30 messages (the number of messages presented on the web interface) we can go through the archive pretty quickly. Reviewing the main Boost list, on the other hand... -- Jim

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Building boost into another directory.
by tlolczyk 23 Apr '02

23 Apr '02

I want to build boost so that it gets installed in a directory other than the one that it is extracted to. I did it once but I can't figure out how I did it. Can anyone help?

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crc
by GIE 22 Apr '02

22 Apr '02

Hello. I have problem compiling following empty project: #include "stdafx.h" //-------------------------------------------------------------------------- - #include <boost/config.hpp> #include <boost/cstdint.hpp> // for boost::uint16_t, etc. #include <boost/crc.hpp> //-------------------------------------------------------------------------- - int _tmain(int argc, _TCHAR* argv[]) { return 0; } //-------------------------------------------------------------------------- - with following errors: d:\compil\vc_libs\boost_1_27_0\boost\crc.hpp(71) : error C2059: syntax error : '<constant tree>' d:\compil\vc_libs\boost_1_27_0\boost\crc.hpp(94) : error C2977: 'boost::crc_optimal' : too many template arguments d:\compil\vc_libs\boost_1_27_0\boost\crc.hpp(75) : see declaration of 'boost::crc_optimal' d:\compil\vc_libs\boost_1_27_0\boost\crc.hpp(95) : error C2977: 'boost::crc_optimal' : too many template arguments d:\compil\vc_libs\boost_1_27_0\boost\crc.hpp(75) : see declaration of 'boost::crc_optimal' d:\compil\vc_libs\boost_1_27_0\boost\crc.hpp(96) : error C2977: 'boost::crc_optimal' : too many template arguments d:\compil\vc_libs\boost_1_27_0\boost\crc.hpp(75) : see declaration of 'boost::crc_optimal' d:\compil\vc_libs\boost_1_27_0\boost\crc.hpp(98) : error C2977: 'boost::crc_optimal' : too many template arguments d:\compil\vc_libs\boost_1_27_0\boost\crc.hpp(75) : see declaration of 'boost::crc_optimal' d:\compil\vc_libs\boost_1_27_0\boost\crc.hpp(258) : error C2983: 'boost::crc_optimal' : new template parameter list has more parameters than the previous declaration d:\compil\vc_libs\boost_1_27_0\boost\crc.hpp(258) : see declaration of 'boost::crc_optimal' d:\compil\vc_libs\boost_1_27_0\boost\crc.hpp(214) : error C2062: type '<template parameter>' unexpected d:\compil\vc_libs\boost_1_27_0\boost\crc.hpp(258) : see reference to class template instantiation 'boost::crc_optimal<,TruncPoly,InitRem,FinalXor,,>' being compiled What is the proplem? I'm using MS VC 7. -- Best regards, GIE

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Jam and include dirs.
by tlolczyk 22 Apr '02

22 Apr '02

My gcc include idrectories are in a nonstandard location. What do I modify in Jam to cause -I/myinclude to be added to the compile line.TIA

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