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Re: Lambda shortcut?
by Daryle Walker 27 Aug '03

27 Aug '03

On Tuesday, August 26, 2003, at 10:05 AM, Jaakko Jarvi wrote: > In our last exciting episode Stephen Love wrote: >> operator-> *is* overloadable. > > It is, but not freely. The return type cannot be arbitrary, say a > lambda_functor type, making it not very useful for the LL. Specifically, the right side of "->" must be the NAME of a class' member or member function. It cannot be any kind of actual object (including pointers-to-member). This restricts the left side to: 1. A pointer to a (class/struct/union) data object (conventional C usage) 2. A class object with an "operator ->()" that returns a pointer to a data object 3. A class object with an "operator ->()" that returns an object that follows rules [2] or [3]. No matter what, "operator ->()" eventually leads to the standard C usage. All you can do is delay the event and build proxy objects to obtain the data. Daryle

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Link errors
by Ken Crismon 26 Aug '03

26 Aug '03

To all, I am a new user to the BOOST community and am putting together some test code to get a handle on what BOOST is and how it works. Am using .NET 2003 and am getting the following link errors. error LNK2019: unresolved external symbol "__declspec(dllimport) public: class std::_Ptrit<char,int,char *,char &,char *,char &> __thiscall std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::end(void)" Thanks in advance for the help, Ken Crismon

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First Boost installation under Windows and Borland
by Matías Nicolás Bossa 26 Aug '03

26 Aug '03

Hello, I'm a new Boost user and I need to install it (v. 1.30.0) under Windows 2000, with Borland C++ Builder 6. I've succeed in correctly installing and using it under linux, but I couldn't install it under Windows. I downloaded and unpacked boost_1_30_0.zip. I set the following variables: BOOST_ROOT=d:\proyect\boost_1_30_0 TOOLS=borland BCCROOT=c:\archiv~1\borland\cbuilder6 PYTHON_ROOT=c:\win\python I compiled bjam.exe by running tools\build\jam_scr\build.bat, and put it somewhere in the path. (but I also tried downloading a precompiled version) I run bjam from the boost_1_30_0 directory and the following message appeared: /****************************************************/ /****************************************************/ ...found 5339 targets... ...updating 573 targets... borland-C++-action libs\python\build\bin\boost_python.dll\borland\debug\runtime-link-dynamic\numeric.obj libs\python\build\../src\numeric.cpp: Error E2401 D:\project\boost_1_30_0\boost/python/object/inheritance.hpp 69: Invalid template argument list Error E2040 D:\project\boost_1_30_0\boost/python/object/inheritance.hpp 69: Declaration terminated incorrectly Error E2231 D:\project\boost_1_30_0\boost/python/object/inheritance.hpp 130: Member cast_generator<Source,Target>::is_upcast cannot be used without an object Error E2401 D:\project\boost_1_30_0\boost/python/object/inheritance.hpp 131: Invalid template argument list Error E2040 D:\project\boost_1_30_0\boost/python/object/inheritance.hpp 132: Declaration terminated incorrectly Error E2228 D:\project\boost_1_30_0\boost/python/object/inheritance.hpp 132: Too many error or warning messages *** 6 errors in Compile *** /****************************************************/ /****************************************************/ For the moment I just need ublas and random libraries, I need boost in order to compile another library which use it, called Bayes++. I wil be very grateful if someone could help me, and I'm sorry for the length of the mail. Regards, Matías ___________________________________________________ Yahoo! Messenger - Nueva versión GRATIS Super Webcam, voz, caritas animadas, y más... http://messenger.yahoo.es

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Lambda shortcut?
by Hurd, Matthew 26 Aug '03

26 Aug '03

Hi, Is there a short cut for bind(&class::method_name, this, _1)? I could wrap it in a macro, as I use it enough, but is there something nicer I'm missing? I often just do the for loop as it is a little more readable, maybe... For example, for( some_collection::iterator i = check_list.begin(); i!= check_list.end(); ++i ) { turn_off_calcs(*i); } Is hopefully the same as for_each( check_list.begin(), check_list.end(), lambda::bind(&instrument_store::turn_off_calcs,this,lambda::_1) ); Regards, Matt.

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How to use boost::bind
by Darren Cook 26 Aug '03

26 Aug '03

Hi, I have a project with many occurences of while loops iterating through a container, and operating on the data. I'd like to use for_each() and turn them into one-liners, but I don't like writing one-off functor classes. I was hoping boost::bind could help, but I've read the docs, scratched my head, and failed to work out how the examples apply to my case. Maybe they don't and I'm trying to use it for something it cannot do? See an example below. My function currently looks something like grab_keys() and I want it to look like grab_keys2(). Could some kind soul show me how to write this? (or explain why it cannot be written). Thanks, Darren ------------------------- class Info{ public: int key; std::set<int> points; }; class InfoContainer{ public: Info* get(int); }; void grab_keys(const InfoContainer &cs,const Info *c){ std::set<int> list; std::set<int>::const_iterator i=c->points.begin(); while(i!=c->points.end()){ Info *ec=cs.get(*i++); list.add(ec->key); //Previous two lines could be written: list.add(cs.get(*i++)->key); } //Do something with list here. } void grab_keys2(const AllInfo &cs,const Info *c){ Points list; std::for_each(c->points.begin(),c->points.end(), boost::bind( /* what goes here? */ ) ); //Do something with list here. }

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newbie: comand line for g++
by Ruslan Talpa 26 Aug '03

26 Aug '03

how to staticaly link a boost library (regex) to a project (what is the g++ command line for that) Thanks PS i have only used VC till now.

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XML output from Boost test framework.
by Jarl Friis 26 Aug '03

26 Aug '03

Hi. The release notes on Boost test framework says: XML log format is introduced XML report format is introduced I would like to know how I use those features, the documentation says nothing about it, at least I can't find it. Thanks in advance. Jarl

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ClearCase and Boost
by Matt Trentini 26 Aug '03

26 Aug '03

Heya, The best way I've found to import Boost into ClearCase is by using "clearfsimport". If anyone wants a hand in setting up the parameters (it's a bit tricky - please make sure you don't use the mklabel and preview options together, otherwise you'll lock the VOB!) let me know. Cheers, Matt

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filesystem in CVS differs from 1.30.x ?
by Anders Moe 26 Aug '03

26 Aug '03

Hi all. I'm somewhat confused about how to use filesystem, since it appears that the CVS version differs from 1.30.x. In particular, the following simple snippet suddenly wouldn't compile on 1.30.2 using MSVC 7.1: boost::filesystem::path p("dd"); boost::filesystem::ofstream os("dd"); It works, however, with the current CVS version. In fact, I have failed to compile any variant of the above under 1.30.2. Regards, Anders Moe.

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mem mapping containers
by spam_me_da 25 Aug '03

25 Aug '03

I'd like to know if there is any available implementation of a memory mapped linear array. (Linux) Thanks -K

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