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Re: [Boost-users] enable_shared_from_this - or an alternative..
by James Hughes 20 Mar '06

20 Mar '06

> -----Original Message----- > From: Alan M. Carroll [mailto:amc@network-geographics.com] > Sent: 20 March 2006 13:44 > To: boost-users(a)lists.boost.org > Cc: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] enable_shared_from_this - or an > alternative.. > > > At 04:13 AM 3/20/2006, James Hughes wrote: > >Hello All, > > > >I have a couple of classes that I want to self register > themselves with a > >monitoring class. To do this they must pass a shared_ptr of > themselves to > >the monitor register function. > > > >Therefore I need to make a shared_ptr form the this pointer, in the > >constructor. > > Why not use intrusive_ptr? Way back when, I wrote my own > equivalent of that instead of using Boost.shared_ptr partly > for this very reason (i.e., having to use smart pointers in > constructors). > Ah, just read my Boost book on intrusive pointers and I think they would work. Not sure I will use for current issues, as have now written code for a factory mechanism (which appears to work!), but certainly worth knowing for the future. Thanks Rgds James

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Unicode support
by Calderon Hector 20 Mar '06

20 Mar '06

Is there any rationale for not supporting Unicode in some boost libraries (e.g. filesystem, program_options)? ++Hector C. ---------------------------------- --------------------------------- Yahoo! Mail Use Photomail to share photos without annoying attachments.

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Re: [Boost-users] enable_shared_from_this - or an alternative..
by James Hughes 20 Mar '06

20 Mar '06

> > > >> > > _______________________________________________ > > Boost-users mailing list > > Boost-users(a)lists.boost.org > > http://lists.boost.org/mailman/listinfo.cgi/boost-users > > > is the following snipped what you have in mind? > > struct base {}; > struct derived1 : public base {}; > struct derived2 : public derived1 {}; > > typedef boost::shared_ptr<base> base_ptr; > > struct monitor > { > void > add( const base_ptr & _ptr) > { > // ... > } > }; > > struct factory > { > factory( monitor & _monitor ) : > monitor_(_monitor) > { > } > > template<typename T> > boost::shared_ptr<T> > create( void ) > { > boost::shared_ptr<T> tmp(new T); > monitor_.add(tmp); > return tmp; > } > > private: > monitor & monitor_; > }; > > void > foo( void ) > { > monitor m; > factory f(m); > f.create<derived1>(); > f.create<derived2>(); > } > > -- dave > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users > Hi Dave, Yes, I think that pretty much does exactly what I require. And gives me a (almost comnpletely) generic factory class to boot! Thanks very much! James

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bjam and Intel 8 on windows
by Andreas Fabri 20 Mar '06

20 Mar '06

Hello, I just tried to install boost for the Intel 8 Compiler. bjam.exe "-sTOOLS=intel-win32" install failed updating 948 targets... skipped 412 targets... updated 3323 targets... Didn't I choose the right toolset? If I only want to create program_options, is this the right command: bjam.exe "-sTOOLS=intel-win32 --with-program_options" install thanks in advance, andreas

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Re: [Boost-users] enable_shared_from_this - or an alternative..
by Alan M. Carroll 20 Mar '06

20 Mar '06

At 04:13 AM 3/20/2006, James Hughes wrote: >Hello All, > >I have a couple of classes that I want to self register themselves with a >monitoring class. To do this they must pass a shared_ptr of themselves to >the monitor register function. > >Therefore I need to make a shared_ptr form the this pointer, in the >constructor. Why not use intrusive_ptr? Way back when, I wrote my own equivalent of that instead of using Boost.shared_ptr partly for this very reason (i.e., having to use smart pointers in constructors).

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Re: [Boost-users] enable_shared_from_this - or an alternative..
by David Klein 20 Mar '06

20 Mar '06

boost-users-bounces(a)lists.boost.org wrote: >> -----Original Message----- >> From: David Klein [mailto:d.klein@ascaron.com] >> Sent: 20 March 2006 10:27 >> To: boost-users(a)lists.boost.org >> Subject: Re: [Boost-users] enable_shared_from_this - or an >> alternative.. >>> [snip] > > Thanks Dave, that does cover the problem well. > > However, I cannot use the null deleter mechanism suggested as the > shared_ptr is passed on to monitor and is used there. The second > scheme, using a factory fucntion, would seem to be approriate, > however, how to I handle creation when the CSource1 class is actually > to be used as a base class? If the factory function is in CSource1, > it doesnt know about any derived classes. I don't want to have to > write factory functions in every dervied class - that seems a waste. > Is there a correct technique for getting around this issue? I am > assuming a template of some description, but now sure what that > entails. > > > > > James > >> > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users is the following snipped what you have in mind? struct base {}; struct derived1 : public base {}; struct derived2 : public derived1 {}; typedef boost::shared_ptr<base> base_ptr; struct monitor { void add( const base_ptr & _ptr) { // ... } }; struct factory { factory( monitor & _monitor ) : monitor_(_monitor) { } template<typename T> boost::shared_ptr<T> create( void ) { boost::shared_ptr<T> tmp(new T); monitor_.add(tmp); return tmp; } private: monitor & monitor_; }; void foo( void ) { monitor m; factory f(m); f.create<derived1>(); f.create<derived2>(); } -- dave

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Re: [Boost-users] enable_shared_from_this - or an alternative..
by James Hughes 20 Mar '06

20 Mar '06

> -----Original Message----- > From: David Klein [mailto:d.klein@ascaron.com] > Sent: 20 March 2006 10:27 > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] enable_shared_from_this - or an > alternative.. > > > boost-users-bounces(a)lists.boost.org wrote: > > Hello All, > > > > I have a couple of classes that I want to self register themselves > > with a monitoring class. To do this they must pass a shared_ptr of > > themselves to the monitor register function. > > > > Therefore I need to make a shared_ptr form the this pointer, in the > > constructor. > > > > I have derived my classes from > enabled_shared_from_this...(code to get > > monitor omitted) > > > > //psuedo code.. > > monitor::AddSource1(boost::shared_ptr<CSource1>); > > monitor::AddSource2(boost::shared_ptr<CSource2>); > > > > class CSource1 : public enable_shared_from_this<CSource1> > > { > > CSource1() { Monitor->AddSource(shared_from_this()); }; > > } > > > > and > > > > class CSource2 : public base1, public > > enable_shared_from_this<CSource2> { > > CSource2() { Monitor->AddSource(shared_from_this()); };} > > } > > > > > > This all compile fine, but when run, the shared_from_this call > > asserts with a bad weak ptr - at the time of calling the > weak_ptr has > > no content, and looking at the boost code, I cannot see where it is > > supposed to get set to access the this value. > > > > Should I be using enable_shared_from_this in this way or is there a > > better way to convert the this ptr to a shared_ptr in a constructor > > that I need to use. > > > > > > James > > _______________________________________________ > > Boost-users mailing list > > Boost-users(a)lists.boost.org > > http://lists.boost.org/mailman/listinfo.cgi/boost-users > > hi james, > > see: http://boost.org/libs/smart_ptr/sp_techniques.html#in_constructor > > HTH dave > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users Thanks Dave, that does cover the problem well. However, I cannot use the null deleter mechanism suggested as the shared_ptr is passed on to monitor and is used there. The second scheme, using a factory fucntion, would seem to be approriate, however, how to I handle creation when the CSource1 class is actually to be used as a base class? If the factory function is in CSource1, it doesnt know about any derived classes. I don't want to have to write factory functions in every dervied class - that seems a waste. Is there a correct technique for getting around this issue? I am assuming a template of some description, but now sure what that entails. James >

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enable_shared_from_this - or an alternative..
by James Hughes 20 Mar '06

20 Mar '06

Hello All, I have a couple of classes that I want to self register themselves with a monitoring class. To do this they must pass a shared_ptr of themselves to the monitor register function. Therefore I need to make a shared_ptr form the this pointer, in the constructor. I have derived my classes from enabled_shared_from_this...(code to get monitor omitted) //psuedo code.. monitor::AddSource1(boost::shared_ptr<CSource1>); monitor::AddSource2(boost::shared_ptr<CSource2>); class CSource1 : public enable_shared_from_this<CSource1> { CSource1() { Monitor->AddSource(shared_from_this()); }; } and class CSource2 : public base1, public enable_shared_from_this<CSource2> { CSource2() { Monitor->AddSource(shared_from_this()); };} } This all compile fine, but when run, the shared_from_this call asserts with a bad weak ptr - at the time of calling the weak_ptr has no content, and looking at the boost code, I cannot see where it is supposed to get set to access the this value. Should I be using enable_shared_from_this in this way or is there a better way to convert the this ptr to a shared_ptr in a constructor that I need to use. James

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Re: [Boost-users] enable_shared_from_this - or an alternative..
by David Klein 20 Mar '06

20 Mar '06

boost-users-bounces(a)lists.boost.org wrote: > Hello All, > > I have a couple of classes that I want to self register themselves > with a monitoring class. To do this they must pass a shared_ptr of > themselves to the monitor register function. > > Therefore I need to make a shared_ptr form the this pointer, in the > constructor. > > I have derived my classes from enabled_shared_from_this...(code to get > monitor omitted) > > //psuedo code.. > monitor::AddSource1(boost::shared_ptr<CSource1>); > monitor::AddSource2(boost::shared_ptr<CSource2>); > > class CSource1 : public enable_shared_from_this<CSource1> > { > CSource1() { Monitor->AddSource(shared_from_this()); }; > } > > and > > class CSource2 : public base1, public > enable_shared_from_this<CSource2> { > CSource2() { Monitor->AddSource(shared_from_this()); };} > } > > > This all compile fine, but when run, the shared_from_this call > asserts with a bad weak ptr - at the time of calling the weak_ptr has > no content, and looking at the boost code, I cannot see where it is > supposed to get set to access the this value. > > Should I be using enable_shared_from_this in this way or is there a > better way to convert the this ptr to a shared_ptr in a constructor > that I need to use. > > > James > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users hi james, see: http://boost.org/libs/smart_ptr/sp_techniques.html#in_constructor HTH dave

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newbie question: how to make boost helloworld in linux
by kdsfinger＠gmail.com 20 Mar '06

20 Mar '06

hi, boost users Can someone tell me how to build boost helloworld.cpp in linux using g++? I have boost installed via yum in my fc3 box. Here is my code. //test.cpp #include <boost/shared_ptr.hpp> #include <iostream> int main(){ std::cout<<"helloworld"; return 0; } g++ test.cpp //can't find boost. Thanks in advance. zl2k

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