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Re: Re: Re: Is there any way to get typeid() to return the derived class name?
by Chris Just 02 Mar '05

02 Mar '05

Jody Hagins wrote: >> I'm using MS Visual C++ 6.0. This is what I'm doing: >> When I look at the type_info object's name(), it always returns >> "CBase", even if it's actually a CDerived object. > > > You have ommitted the most important pieces in your code sample... > > > Compile and run the above on your compiler. If it fails, you have a > problem with your compiler. Otherwise, you probably have a problem with > your code. Note that you only get the most derived type, if the class > is polymorphic (i.e., has at least one virtual function). Thanks, that fixed it. I could have sworn I tried that before, but I guess not... :) __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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Re: Singleton is documented!
by Jason Hise 01 Mar '05

01 Mar '05

I just got a message from Michel Decima regarding an interesting problem. What happens when you have to use a library which maintains static or global variables that you don't have control over, and you need your singletons to have access to them? The answer is that you have to make sure that your singletons get destroyed before or as main ends, not after. To do so, you have one of three options: A) Use the dependency_lifetime and make sure not to keep any static or global pointers. B) Explicitly call destroy on each of your singletons before main exits. C) Explicitly destroy the secret singleton boost::singleton::detail::longevity_registry before main exits. I recommend option three, combined with some RAII. For example: struct CleanupSingletons ( ) { ~ CleanupSingletons ( ) { boost::singleton::detail::longevity_registry::pointer ( ).destroy ( ); } }; int main ( ) { CleanupSingletons cleanup; //... return 0; } I wonder if this functionality is useful enough that I should add a non-member function 'cleanup' directly in the singleton namespace which destroys the longevity_registry internally. Thoughts and opinions? -Jason

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Re: MPL integral wrapper failure on gcc4
by Aleksey Gurtovoy 01 Mar '05

01 Mar '05

Jeff Garland writes: > I realize this is an experimental compiler, but I notice date-time > isn't building because of an MPL failure. Similar problem in the > MPL tests. I looked at the code, but I have no idea what the > problem could be, possibly something simple? Just looked into it, and it appears to be a GCC bug: they seem to disallow any cast notation in integral constant expressions, while section 5.19 [expr.const] para 1 explicitly allows type conversions to integral or enumeration types: [...] Floating literals (2.13.3) can appear only if they are cast to integral or enumeration types. Only type conversions to integral or enumeration types can be used. [...] If you could verify that the following stripped down version of the code in question is rejected, I'd submit a corresponding bug report: template< int n > struct int_ {}; typedef int_< static_cast<int>(5) > n; -- Aleksey Gurtovoy MetaCommunications Engineering

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Iostreams questions
by christopher diggins 01 Mar '05

01 Mar '05

Several questions, 1) There is the (apparently) undocumented pipe operator http://www.ootl.org/boost/iostreams/pipable.hpp.htm . What does it do exactly? It appears to push filters into a filtering_stream or filtering_streambuf, but I am unsure. 2) Can we use it to write arbitrarily long chains such as: source | input_filter | bidirectional_filter | output_filter | sink? 3) why the name bidirectional_filter when inputoutput_filter (or io_filter) would be apparently more consistent with stl naming convention? 4) what is the url for the latest version and what is the status? Thanks! Christopher Diggins Object Oriented Template Library (OOTL) http://www.ootl.org

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Re: [boost] RPC library
by Iain Hanson 01 Mar '05

01 Mar '05

Hi, On Tue, 2005-03-01 at 14:09 +0000, Jarl Lindrud wrote: > Hi all, > > I've searched this list a bit and found a few mentions of rpc's (Remote > Procedure Call), but nothing concrete. > > I've written a library for doing portable C++ RPC's, which can be downloaded at > > http://www.codeproject.com/threads/RMI_For_Cpp.asp > > Is there any interest in Boost for something like this, and if so in what > directions do you all think it should be developed? Nice idea. Unfortunately RPC's ( including Java RMI ) don't scale. Thats why CORBA and J2EE were created. Simple RPC mechanisms like this inevitably end up being extended piece by piece until you have reproduced most of the CORBA functionality. Therefore IMHO I don't think it is a good idea for boost. /ikh

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RE: [boost] Re: Re: Re: Iostreams Question: Bestwaytooutputtowin32debugger\outwindow ?
by Brian Braatz 01 Mar '05

01 Mar '05

> -----Original Message----- > From: boost-bounces(a)lists.boost.org [mailto:boost-bounces@lists.boost.org] > On Behalf Of Jonathan Turkanis > Sent: Monday, February 28, 2005 10:26 PM > To: boost(a)lists.boost.org > Subject: [boost] Re: Re: Re: Iostreams Question: > Bestwaytooutputtowin32debugger\outwindow ? > > Reid Sweatman wrote: > >> -----Original Message----- > >> From: boost-bounces(a)lists.boost.org > >> [mailto:boost-bounces@lists.boost.org] On Behalf Of Jonathan Turkanis > > >> Okay Brian, > >> > >> The following apparently works, but when OutputDebugString is > >> called I don't see any output. I'm not sure if the previous > >> version worked or not; I've run out of time for now. > > > > I didn't see most of this thread, and may be totally off-base here, > > but you need to use a tool that can intercept the output from > > OutputDebugString(), > > as that function assumes there's a debugger attached to its process; > > if there's no attached debugger, it attempts to use the Windows system > > debugger, which must be both installed and active. However, I like > > SysInternals' DebugView, both because it's well-written and easy to > > use, and because it's free. Very lightweight alternative to invoking > > a full debugger when that would be overkill. It can do kernel-mode > > debugging, too, which is a major plus, if you need that; got a copy > > running on my other machine right now. www.sysinternals.com. And if > > this is not to the point, or you already know all this, bear in mind > > that I only had this post available, and skimmed it pretty cursorily, > > and please just disregard my post. > > Thanks for the info. > > The main point of the thread was to show how to write a sink with a built- > in > line-ending filter, so the user doesn't always have to add one explicitly. > > Jonathan > [Brian Braatz Writes:] Yes. (sorry if I got off base)- the question relevant to boost \ iostreams was this- Given a device which has different line termination than \n, how do you handle it in such a way that allows for that device to be able to interpret std::endl so it works as the user would expect. (and so the code you write using the sink makes sense to the user) I happen to be using win32's outputdebugstring, but the same issue applies for "printing" to a windows edit control. The same issue might also apply to a daisy wheel printer. And, personally, I think boost should support daisy wheel printers (grin)....

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Re: Re: Is there any way to get typeid() to return the derived class name?
by Chris Just 01 Mar '05

01 Mar '05

Jody Hagins wrote: >> I've been looking through the boost library and I haven't been able to >> find anything that works like typeid() that returns the exact (i.e. >> derived) class name instead of just the base class. >> I want to compare two derived classes to make sure that they are of >> the same class, but typeid() only returns the name of the base class. >> >> If there is a boost function that does this, or if someone has a way >> of doing it could you please point me in the right direction? > > Funny about timing... > > I think I can answer your question, but I must answer with another > question. What do you mean by "typeid() only returns the name of the > base class?" This is surely not the case for polymorphic types, at > least according to the standard. Maybe if you post a bit of code, which > represents what you are trying to accomplish, I can help... I'm using MS Visual C++ 6.0. This is what I'm doing: CBase { ... }; CDerived : public CBase { ... }; CSomething { public: CSomething( const CBase& base ) : m_Base( base ) {} CSomething& operator=( const CSomething& rhs ) { if ( typeid( m_Base ) != typeid( rhs.m_Base ) ) // This never fails. { throw exception(); } } private: CBase& m_Base; }; When I look at the type_info object's name(), it always returns "CBase", even if it's actually a CDerived object. __________________________________ Do you Yahoo!? Yahoo! Mail - now with 250MB free storage. Learn more. http://info.mail.yahoo.com/mail_250

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Select overload revisited
by Daniel James 01 Mar '05

01 Mar '05

I was thinking about the overload resolution functions suggested a while back by Arturo Cuebas[1] and had no idea why the compiler needs to be told the number of parameters in the first place. So I took his code and removed the numbers from functions, and it worked (in gcc). I guess that it didn't work for him because of his compiler. Well, it almost worked. Sometimes there is more than the one function that fits the template parameters. So I kept the numbered overloads to be able to match them. It might be possible to get these to work without the number of parameters by making the compiler prefer overloads for functions with less parameters. I've attached a demo. Daniel [1] http://lists.boost.org/MailArchives/boost/msg69451.php

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Added "restore" member functions to ios_state
by Daryle Walker 01 Mar '05

01 Mar '05

See "BOOST_ROOT/boost/io/ios_state.hpp," CVS version 1.3, and "BOOST_ROOT/libs/io/doc/ios_state.html," CVS version 1.7, if they uploaded OK. (I had a temporary[?] wait on my own lock.) -- Daryle Walker Mac, Internet, and Video Game Junkie darylew AT hotmail DOT com

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build boost1_32_0 lib on solaris 9.
by JIM WANG, BLOOMBERG/ SKILLMAN 01 Mar '05

01 Mar '05

Hi all, i am building build libraries for version 1_32_0 on solaris 9 but running into many errors. For example, there are similar errors like in compiling serialization/build/../src/xml_wgrammar.cpp:14: #error "wide char i/o not supported on this platform" The command i used is: bjam "-sTOOLS=gcc" --with-python-root=/usr/local/Python2.3.2 install Are there any detailed procedures for build on solaris 9? Thanks

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