March 2005 - Boost - lists.boost.org

[program_options] Patch to fix 64bit error and warning
by Jonathan Wakely 23 Mar '05

23 Mar '05

The attached patch fixes a 64 bit portability problem where std::string::size_type is assigned to unsigned, which is shorter than size_t on x86-64 and so will be truncated. This means the following comparison to std::string::npos is always false. Patch also prevents a warning with GCC; since the compiler doesn't know that boost::throw_exception never returns it thinks that cmdline::translate_property() can reach the end of the function without returning. The patch simply removes the "else" so that throw_exception is always called if control reaches the end of the function. A better solution might be to mark boost::throw_exception() with __attribute__((unused)) for GCC. The first change is required, the second is optional. jon -- "More computing sins are committed in the name of efficiency (without necessarily achieving it) than for any other single reason - including blind stupidity." - W.A. Wulf

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Re: Asynchronous I/O
by Hans Malherbe 23 Mar '05

23 Mar '05

--- Don G skryf: >Of the mechanisms discussed, I am not sure I understand what you mean >by async I/O with only one thread. I can imagine a nonblocking/select >style approach that has no extra threads, but as soon as the main >thread is not waiting on I/O itself (my interpretation of "async"), >there needs to be threads to do the waiting. The main thread does the waiting. In Windows NT you will either wait on the event flag in the OVERLAPPED structure or specify a completion routine and wait in an alertable state with the SleepEx or one of the *WaitFor*ObjectsEx functions. Groete Hans Malherbe ______________________________________________ "This information is intended only for the person or entity to which it is addressed and may contain private, confidential, proprietary and/or privileged material and may be subject to confidentiality agreements. Any review, retransmission, dissemination, or any other use of or taking of any action in reliance upon this information, by persons or entities other than the intended recipient, is prohibited. If you received this in error, please contact the sender and delete the material from all storage media. The company is neither liable for proper, complete transmission of the information contained in this communication, any delay in its receipt or that the mail is virus-free"

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Re: Re: FSM review
by Andreas Huber 22 Mar '05

22 Mar '05

Rob Stewart wrote: [snip] > Without digging out the previous messages and confirming the > matter, I think Jonathan's suggestion, quoted above, was simply > that *when* the user wants separate translation units *and* the > features that would typically require tight coupling, you could > introduce a weaker link -- some form of indirection -- that would > slow the resulting FSM or even complicate its specification, but > would at least permit the functionality. I think that's close to what I understood... [snip] > This is right on target. *Since* the current design, with all of > its requirements is so much slower, then the onus is on Andreas > to explain why the requirements his library meets exceed those > met by other FSM libraries and directly lead to the performance > overhead. Clear distinctions regarding the performance > improvements gained by avoiding the performance draining features > in an FSM while still using this library will help to demonstrate > that situation, too. [and] [snip] >> Normally, in designing a framework one considers a small handful >> (say two to six) of alternate designs which view the subject matter >> from completely different perspectives. In your case, what were >> those alternate designs? > > Note that Jonathan is asking that those alternatives be > documented. That way, other developers who wonder why you didn't > try X will see that you did and they'll see why you decided it > was not appropriate. I have agreed to add such documentation in one of my previous answers. >> Let me make one last attempt to explain what should be in the >> rationale. Look at section 16.2 of "The C++ Programming Language", >> 3d ed. Here Stroustrup gives two design criteria for a containers >> library, and then discusses three designs: >> >> "Specialized containers and iterators" - satisfies the first >> criterion "Based Containers" - satisfies the second criterion >> "STL" - satifies both criteria >> >> I'm not suggesting that you give such a detailed treatement as >> Stroustrup. However, if you were to give a similar overview of the >> landscape of possible FSM frameworks, and thoughtfully discuss the >> tradeoffs in flexibility and performace which each involves, >> reviewers might have some confidence that you are aware of the >> techniques which might be used to construct a fast, flexible FSM >> framework, and have carefully considered the design. >> >> This type of overview would probably be a useful component of any >> library's documentation; in your case it is made absolutely >> essential by the performance figures you cite. > > I don't think I can add any more to that. I think it is > reasonable and clear. It is but I'm not sure how this is relevant (I already agreed to add such documentation). -- Andreas Huber When replying by private email, please remove the words spam and trap from the address shown in the header.

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implicit_cast has been removed, but this is sad
by Jens Theisen 22 Mar '05

22 Mar '05

implicit_cast was once in cast.hpp, but as the comments says, it has been removed due to uncertain purpose. I have to purposes of which I am wondering how to do them otherwise: 1. take the address of the conversion 2. initialise a std::vector< int > with a boost::assign::list_of in a constructor initialiser The latter is a bit subtle. list_of uses a templated conversion operator to containers (but technically everything) and std::vector's ctor are then all tried with taking converted arguments, which leads into an ambiguity. Using implicit_cast solves the problem, since then the constructor call to std::vector and the call to the conversion operator in list_of are both taken as user defined conversions, and there can only be one of them. vector< int > v = list_of(1)(2); // works vector< int > v(list_of(1)(2)); // ambiguous ctor() : v(implicit_cast< vector< int > >(list_of(1)(2))) { } // ambiguous ctor() : v(list_of(1)(2)) { } // ambiguous Any thoughts on this? Regards, Jens

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Re: [boost] Re: [review] hash functions
by brangdon＠cix.compulink.co.uk 22 Mar '05

22 Mar '05

In-Reply-To: <d1on4o$ijr$1(a)sea.gmane.org> daniel(a)calamity.org.uk (Daniel James) wrote (abridged): > > Admittedly hash_combine is also (nearly) redundant, being definable > > as: > > > > void hash_combine( size_t &hash, const T &t ) { > > hash_range( hash, &t, &t+1 ); > > } > > > > if T does not overload address-of. Note this is currently true because hash_range is defined as having the effect of: void hash_range( size_t &hash, It first, It last ) { for (; first != last; ++first) hash_combine( hash, *first ); } so calling hash_range on a range of 1 element returns the same result as calling hash_combine with that element. > Since nested vectors give different hash values to their flattened > form, I don't think a single element vector should have the same hash > values as it's element. It doesn't. One is: return hash_value( t ); the other is: size_t hash = 0; hash_combine( hash, t ); return hash; All the proposed definitions of hash_combine make these different. There is at least an xor, and possible a constant added. -- Dave Harris, Nottingham, UK

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Re: [boost] Re: [review] hash functions
by brangdon＠cix.compulink.co.uk 22 Mar '05

22 Mar '05

In-Reply-To: <003501c52a54$a28c4b90$6601a8c0@pdimov> pdimov(a)mmltd.net (Peter Dimov) wrote (abridged): > > size_t hash_value( int v ) { > > return size_t(v) + default_seed; > > } > > I wonder what do we gain from this. As you pointed out when I first suggested adding the constant in hash_combine: This would mean N fixes for a sequence of length N, when one simple fix is enough. The initial value of the seed is arbitrary so we can vary it at will. hash_combine, on the other hand, is based on research and has apparently been selected as one of the best amongst the shift+xor family. This doesn't mean that it's sacred, just that if we change it we'll no longer be able to just point at a PDF as a rationale but will need to do our own research (which might be a good idea anyway, though.) :-) > From the point of view of hash_combine the effect is the same The difference shows when you have something like: struct A { int x, y; }; struct B { A a, b, c; }; size_t hash_value( const A &a ) { size_t hash = 0xbead1; hash_combine( hash, a.x ); hash_combine( hash, a.y ); return hash; } size_t hash_value( const B &b ) { size_t hash = 0xbead2; hash_combine( hash, b.a ); hash_combine( hash, b.b ); hash_combine( hash, b.c ); return hash; } Here hash_combine is called 9 times, but hash_value(int) is only called 6 times, so we get different results depending on where the constant is added. > and we now rely on the user overloads of hash_value to not produce > a zero. That's surely reasonable. The hash_value of any user-defined class should be defined in terms of the hash_values of primitives, and boost provides all of those. > This reflects their intended use. The two argument overload is used > when one has a whole range and wants its hash value, as in the > hash_value overload for std::vector, for example. I actually think this is going to be fairly rare. This is mainly because there will usually be a constant thrown in to represent the type of the object. (I appreciate you won't do that for std containers, but I maintain its a good idea for user-defined types.) The 2-argument version is strictly redundant as it must be defined in terms of the 3-argument version. It's just a convenience function, used mainly by the std containers. Admittedly hash_combine is also (nearly) redundant, being definable as: void hash_combine( size_t &hash, const T &t ) { hash_range( hash, &t, &t+1 ); } if T does not overload address-of. Incidently, do you agree we will sometimes want to pass a hash value as the second argument to hash_combine? Like: hash_combine( hash, hash_range( first, last ) ); hash_combine( hash, obj.get_hash( some_arg ) ); If not, then maybe we should have a hash_combine that just combines hashes. At the moment the combining is mixed in with the getting; it's not a very orthogonal API. -- Dave Harris, Nottingham, UK

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Re: [boost] Re: [review results] hash functions accepted
by brangdon＠cix.compulink.co.uk 22 Mar '05

22 Mar '05

In-Reply-To: <d1p2mg$mfk$1(a)sea.gmane.org> nesotto(a)cs.auc.dk (Thorsten Ottosen) wrote (abridged): > There is a small utility in the Pointer Container library which is more > general that hash_ptr ect. You can simply say > > unordered_set< MyType*, indirect_fun< boost::hash<MyType> >, > > indirect_fun< std::equal<MyType set; > > for the rare cases where the index is a pointer. OK. It might be worth mentioning in the documentation. -- Dave Harris, Nottingham, UK

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Re: [boost] Re: [review] hash functions
by brangdon＠cix.compulink.co.uk 22 Mar '05

22 Mar '05

In-Reply-To: <007b01c52ede$3ceefd80$6501a8c0@pdimov2> pdimov(a)mmltd.net (Peter Dimov) wrote (abridged): > So, in my opinion, your original suggestion is still the best one, even > though I did not seem to agree at first. ;-) OK. > > If not, then maybe we should have a hash_combine that just combines > > hashes. At the moment the combining is mixed in with the getting; > > it's not a very orthogonal API. > > ... yes, hash_value( size_t ) is the identity function partly for this > reason. Cool. (And this is another argument for adding the non-zero fix in hash_combine rather than hash_value.) -- Dave Harris, Nottingham, UK

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Re: [boost] Re: [review results] hash functions accepted
by brangdon＠cix.compulink.co.uk 22 Mar '05

22 Mar '05

In-Reply-To: <004c01c52edb$d07ee5e0$6501a8c0@pdimov2> pdimov(a)mmltd.net (Peter Dimov) wrote (abridged): > > Is it worth considering using x + x / sizeof(*p) instead? > > This will not work for incomplete types, including void. Good point :-) > I'd prefer equal hash_values for an incomplete T*, complete T*, > and void* with the same value. Indeed. Presumably this means casting to void* eg for the case where sizeof(void*) != sizeof(char *). > We'll lose one potential bit of enthropy when alignof(x) == 16, but > this seems sufficiently rare in practice. I was a bit concerned about cases where the heap produces a de facto alignment. Especially if there is a different pool for each size of object, or a user-defined X::operator new() that allocates from a huge array of X. I guess it can't be helped. -- Dave Harris, Nottingham, UK

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[Boost-bugs] [ boost-Bugs-1168431 ] LEDA graph adaptors do not handle hidden nodes properly
by SourceForge.net 22 Mar '05

22 Mar '05

Bugs item #1168431, was opened at 2005-03-22 10:39 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1168431&group_… Category: graph Group: None Status: Open Resolution: None Priority: 5 Submitted By: Douglas Gregor (dgregor) Assigned to: Douglas Gregor (dgregor) Summary: LEDA graph adaptors do not handle hidden nodes properly Initial Comment: Hidden nodes are completely ignored by the LEDA graph adaptors. This may cause problems when, for instance, there are hidden nodes but the equivalent of vertex_index is used to construct a (BGL) property map. The LEDA adaptors should probably take the same approach as filtered_graph: let num_vertices() return the number of the nodes in the graph plus the number of hidden nodes, but vertices() filters out the hidden nodes. Similarly for edges. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1168431&group_… ------------------------------------------------------- This SF.net email is sponsored by: 2005 Windows Mobile Application Contest Submit applications for Windows Mobile(tm)-based Pocket PCs or Smartphones for the chance to win $25,000 and application distribution. Enter today at http://ads.osdn.com/?ad_id=6882&alloc_id=15148&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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[Boost-bugs] [ boost-Bugs-1168424 ] LEDA adaptors for node_array, edge_array
by SourceForge.net 22 Mar '05

22 Mar '05

Bugs item #1168424, was opened at 2005-03-22 10:36 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1168424&group_… Category: graph Group: None Status: Open Resolution: None Priority: 5 Submitted By: Douglas Gregor (dgregor) Assigned to: Douglas Gregor (dgregor) Summary: LEDA adaptors for node_array, edge_array Initial Comment: LEDA has constructs similar to property maps, called node_array and edge_array, that allow the user to create external mappings from vertices or edges to user-defined data. Both classes are templated over the data type T. The BGL LEDA adaptors should provide a wrapper for these data structures to make them into property maps, so that LEDA graphs and LEDA's form of external property maps can be used with BGL algorithms. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1168424&group_… ------------------------------------------------------- This SF.net email is sponsored by: 2005 Windows Mobile Application Contest Submit applications for Windows Mobile(tm)-based Pocket PCs or Smartphones for the chance to win $25,000 and application distribution. Enter today at http://ads.osdn.com/?ad_id=6882&alloc_id=15148&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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[Boost-bugs] [ boost-Bugs-1168420 ] LEDA graph adaptors for undirected graphs
by SourceForge.net 22 Mar '05

22 Mar '05

Bugs item #1168420, was opened at 2005-03-22 10:33 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1168420&group_… Category: graph Group: None Status: Open Resolution: None Priority: 5 Submitted By: Douglas Gregor (dgregor) Assigned to: Douglas Gregor (dgregor) Summary: LEDA graph adaptors for undirected graphs Initial Comment: The LEDA graph adaptors in the BGL seem to work properly for directed graphs (the LEDA type GRAPH<...>), but there are no corresponding adaptors for the undirected LEDA graph type (UGRAPH<...>). Undirected LEDA graphs follow a very different model than the undirected graphs in the BGL, which will require some special machinery. The LEDA type UGRAPH<...> is actually just a class derived from GRAPH<...> that applies the "make_undirected()" member function upon initialization. make_undirected() moves all of the in-edges of each vertex to the out-edges list. This has several unfortunate consequences: 1) The in-degree of an undirected LEDA graph is always zero, even when the out-degree is greater than zero. The in_edges list is therefore empty. 2) When traversing the list of out-edges for a vertex u, the edges returned may have u as their target but not their source. This breaks an important invariant in the BGL, which mandates that source(e, g)==u if e came from out_edges(u, g). Similarly for in-edges. Thus, an undirected LEDA graph adaptor will need to introduce special adaptors for the out_edge_iterator and in_edge_iterator types, which return a new edge_descriptor type for LEDA that can swap the source and target of a LEDA edge as needed. Additionally, graph-mutating operations (such as add_edge) may need to ensure that the graph remains undirected, as if make_undirected() had been called. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1168420&group_… ------------------------------------------------------- This SF.net email is sponsored by: 2005 Windows Mobile Application Contest Submit applications for Windows Mobile(tm)-based Pocket PCs or Smartphones for the chance to win $25,000 and application distribution. Enter today at http://ads.osdn.com/?ad_id=6882&alloc_id=15148&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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[Boost-bugs] [ boost-Bugs-1168411 ] adjacency_matrix should model BidirectionalGraph
by SourceForge.net 22 Mar '05

22 Mar '05

Bugs item #1168411, was opened at 2005-03-22 10:24 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1168411&group_… Category: graph Group: None Status: Open Resolution: None Priority: 5 Submitted By: Douglas Gregor (dgregor) Assigned to: Douglas Gregor (dgregor) Summary: adjacency_matrix should model BidirectionalGraph Initial Comment: Class template adjacency_matrix should model the BidirectionalGraph concept. This will require the introduction of an in_edge_iterator that strides across the rows of the adjacency matrix. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1168411&group_… ------------------------------------------------------- This SF.net email is sponsored by: 2005 Windows Mobile Application Contest Submit applications for Windows Mobile(tm)-based Pocket PCs or Smartphones for the chance to win $25,000 and application distribution. Enter today at http://ads.osdn.com/?ad_id=6882&alloc_id=15148&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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Re: [boost] Re: [review results] hash functions accepted
by brangdon＠cix.compulink.co.uk 22 Mar '05

22 Mar '05

In-Reply-To: <d1na66$6p2$1(a)sea.gmane.org> daniel(a)calamity.org.uk (Daniel James) wrote (abridged): > > 5. change implementation of hash values for pointers so undefined > > behavior is gone (and consider adding x + (x >> 3) ) > > I'm going to do that. Is it worth considering using x + x / sizeof(*p) instead? -- Dave Harris, Nottingham, UK

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Re: [boost] [review results] hash functions accepted
by brangdon＠cix.compulink.co.uk 22 Mar '05

22 Mar '05

In-Reply-To: <d1mq8d$b5q$1(a)sea.gmane.org> nesotto(a)cs.auc.dk (Thorsten Ottosen) wrote (abridged): > 7. the hash_ptr<> suggestion is better done with general indirected > function Did I miss where this was discussed? To recap, we were talking about adding something like: template<typename T> struct hash_ptr { size_t operator()(const T *p) const { return hash_value( *p ); } }; template<typename T> struct equal_ptr { bool operator()( const T *a, const T *b ) const { return *a == *b; } }; to the hash library for use as, eg: unordered_set< MyType *, hash_ptr<MyType>, equal_ptr<MyType> > What do you mean by using a "general indirected function" instead? -- Dave Harris, Nottingham, UK

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[filesystem] symbolic_link_exists naming AND is_file
by Jeff Garland 22 Mar '05

22 Mar '05

I'm writing a small program with filesystem and I needed to check for symbolic links so I can avoid processing them. I noticed the symbolic_link_exists method and, like all good programmers, didn't read the docs b/c I was sure it didn't do what I needed. So I set about writing a function that would and when I looked at the filesystem implementation I realized I was wrong. I was thinking that symbolic_link_exits would check that a symbolic link points to a valid file -- essentially following the symlink. Any reason why this funtion isn't called is_symlink to match the is_directory call? Also, in the code I'm writing I need to only process regular files. So it would be nice to write: if (is_file(my_path)) { //do stuff } where is_file is defined as follows: // equivalent of if (-d path) in perl // returns !is_directory(p) && !is_symlink(p); bool is_file(fs::path p); Or maybe it could be is_regular_file or is_plain_file if we want to be verbose. Seems like this would be handy to have in the filesystem lib. I can probably be talked into supplying patches ;-) Thoughts? Jeff

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BOOST_CHECK_EQUAL again
by Stefan Slapeta 21 Mar '05

21 Mar '05

Hi, attached are the test cases for BOOST_CHECK_EQUAL on strings. I don't know which of the combinations are actually supported, but as you can see in the comments, it's quite mixed at the moment what does work and what not for Intel and VC. (the comments show failing test cases) Gennadiy, shall I add these test cases or are there some we definitely don't support? BTW, the (commented) results are for 1.32 as the code still doesn't work for Intel at all because of the numeric_limits problem! I tested with VC 7.1 and Intel 8.1. Cheers, Stefan #include <boost/test/test_tools.hpp> int test_main( int, char *[] ) { char const *buf_ptr_cch = "abc"; char const buf_array_cch[] = "abc"; char *buf_ptr_ch = "abc"; char buf_array_ch[] = "abc"; std::string buf_str("abc"); BOOST_CHECK_EQUAL(buf_ptr_cch, buf_ptr_cch); BOOST_CHECK_EQUAL(buf_ptr_cch, buf_array_cch); BOOST_CHECK_EQUAL(buf_ptr_cch, buf_ptr_ch); // VC BOOST_CHECK_EQUAL(buf_ptr_cch, buf_array_ch); BOOST_CHECK_EQUAL(buf_ptr_cch, buf_str); BOOST_CHECK_EQUAL(buf_array_cch, buf_ptr_cch); BOOST_CHECK_EQUAL(buf_array_cch, buf_array_cch); BOOST_CHECK_EQUAL(buf_array_cch, buf_ptr_ch); // VC+Intel BOOST_CHECK_EQUAL(buf_array_cch, buf_array_ch); // Intel BOOST_CHECK_EQUAL(buf_array_cch, buf_str); BOOST_CHECK_EQUAL(buf_ptr_ch, buf_ptr_cch); // VC BOOST_CHECK_EQUAL(buf_ptr_ch, buf_array_cch); // VC+Intel BOOST_CHECK_EQUAL(buf_ptr_ch, buf_ptr_ch); BOOST_CHECK_EQUAL(buf_ptr_ch, buf_array_ch); // VC+Intel BOOST_CHECK_EQUAL(buf_ptr_ch, buf_str); BOOST_CHECK_EQUAL(buf_array_ch, buf_ptr_cch); // Intel BOOST_CHECK_EQUAL(buf_array_ch, buf_array_cch); // Intel BOOST_CHECK_EQUAL(buf_array_ch, buf_ptr_ch); // VC+Intel BOOST_CHECK_EQUAL(buf_array_ch, buf_array_ch); BOOST_CHECK_EQUAL(buf_array_ch, buf_str); BOOST_CHECK_EQUAL(buf_str, buf_ptr_cch); BOOST_CHECK_EQUAL(buf_str, buf_array_cch); BOOST_CHECK_EQUAL(buf_str, buf_ptr_ch); BOOST_CHECK_EQUAL(buf_str, buf_array_ch); BOOST_CHECK_EQUAL(buf_str, buf_str); return 0; }

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RE: [boost] Re: google going open source
by Brian Braatz 21 Mar '05

21 Mar '05

Just quickly- I am making good progress on app integration and adding to the Profiler library by Chris Diggins. I will be mailing out more info in the next few weeks. Additionally- a quick look at below looks like it would be something that would add value to profiler lib. I plan on taking a deeper look at that and will report back what I see. I want to REALLY spend some time with below to understand it better\ see how it could fit in with current profiler being worked on. THANK YOU for sending this out, very interesting.... > -----Original Message----- > From: boost-bounces(a)lists.boost.org [mailto:boost-bounces@lists.boost.org] > On Behalf Of Martin Wille > Sent: Friday, March 18, 2005 12:50 AM > To: boost(a)lists.boost.org > Subject: Re: [boost] Re: google going open source > > Thorsten Ottosen wrote: > > "Bronek Kozicki" <brok(a)rubikon.pl> wrote in message > > news:4239ED44.5090508@rubikon.pl... > > | under BSD 2.0 license > > | http://code.google.com/ > > | > > > > Hm...would anyone volenteer to boostify > > https://sourceforge.net/projects/goog-perftools/, > > Can't be done, due to the license. > > Regards, > m > > _______________________________________________ > Unsubscribe & other changes: > http://lists.boost.org/mailman/listinfo.cgi/boost

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Mersenne Twister seed fix
by Daniel van der Zee 21 Mar '05

21 Mar '05

I was wondering if the fix to mersenne twister as suggested in http://lists.boost.org/MailArchives/boost/msg78304.php made it into the random number library for the next release. Thanks, Daniel

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RE: [boost] Re: google going open source
by Brian Braatz 21 Mar '05

21 Mar '05

I would also like to request anyone who looks at this or spends time with it share on the list what they have learned. So far, it looks like it is gcc only as shipped, so porting is one area that needs analysis > -----Original Message----- > From: boost-bounces(a)lists.boost.org [mailto:boost-bounces@lists.boost.org] > On Behalf Of Brian Braatz > Sent: Monday, March 21, 2005 9:22 AM > To: boost(a)lists.boost.org > Subject: RE: [boost] Re: google going open source > > Just quickly- I am making good progress on app integration and adding to > the Profiler library by Chris Diggins. > > I will be mailing out more info in the next few weeks. > > Additionally- a quick look at below looks like it would be something > that would add value to profiler lib. I plan on taking a deeper look at > that and will report back what I see. I want to REALLY spend some time > with below to understand it better\ see how it could fit in with current > profiler being worked on. > > THANK YOU for sending this out, very interesting.... > > > > -----Original Message----- > > From: boost-bounces(a)lists.boost.org > [mailto:boost-bounces@lists.boost.org] > > On Behalf Of Martin Wille > > Sent: Friday, March 18, 2005 12:50 AM > > To: boost(a)lists.boost.org > > Subject: Re: [boost] Re: google going open source > > > > Thorsten Ottosen wrote: > > > "Bronek Kozicki" <brok(a)rubikon.pl> wrote in message > > > news:4239ED44.5090508@rubikon.pl... > > > | under BSD 2.0 license > > > | http://code.google.com/ > > > | > > > > > > Hm...would anyone volenteer to boostify > > > https://sourceforge.net/projects/goog-perftools/, > > > > Can't be done, due to the license. > >

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[filesystem] include_pathes?
by David Abrahams 21 Mar '05

21 Mar '05

Seems to me that this should be "include_paths," no?? -- Dave Abrahams Boost Consulting www.boost-consulting.com

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How much should I care about allocators?
by Dan Rosen 21 Mar '05

21 Mar '05

Hi all, I'm in the process of putting together my own submission for a boost::tree<>, which has been discussed here on occasion before. Without getting into much detail about the tree itself, I have two nuts-and-bolts questions about conventions using allocators in containers. First: The standard allocator concept has several distinct typedefs: "value_type", "pointer", "reference", etc. My understanding is that the main motivation for allocators was the necessity to abstract out differences in pointer types on different platforms. So I assume this implies that to use an allocator properly, one can't necessarily expect that "pointer" is identical to "value_type*". I hope this assumption is correct so far. What I take this to further imply is that in my container, I need to write code of this nature: template <typename T, typename A = std::allocator<T> > class tree { public: typedef A allocator_type; typedef typename A::value_type value_type; typedef typename A::pointer pointer; typedef typename A::reference reference; // etc. private: class node_t; typedef typename A::template rebind<node_t>::other node_allocator; typedef typename node_allocator::value_type node; typedef typename node_allocator::pointer node_pointer; class node_t { pointer t_; node_pointer parent_; // etc. }; // etc. }; In other words, to respect the allocator I've been given, I need to make sure my internal node structure uses the rebound node allocator's pointer and value types, and so forth. So my first question is, is this assumption correct? The reason I ask is that looking over the standard library implementation that comes with gcc 4.0, I noticed that their implementation of std::list<> has nodes which contain straight pointers, rather than the allocator typedef equivalents. To me that seems to contradict my assumption, assuming the gcc implementation is correct. My second question is about allocator's construct() method. The implementation of std::allocator has construct() invoking the copy ctor using placement new(). That much is self-explanatory. It also seems reasonable to me that allocator does not have construct() methods taking arbitrary parameters. But I'm not sure I understand the reason why it does not have a construct() method to invoke an object's default ctor. What that implies to me, and seems to be supported by gcc's list implementation, is that the nodes in my tree mustn't have a default ctor that actually does anything, because the only way to properly initialize objects using an allocator is through copying. Is that correct? What this boils down to is, using allocators seems to dictate some aspects of how I design and implement this tree (or any container). So how much should I strive to operate within their limitations, and am I understanding these limitations correctly? I hope this is an appropriate forum for these questions. Thanks very much, dr

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[Post review] Pointer Container
by Thorsten Ottosen 20 Mar '05

20 Mar '05

Dear all, The Pointer Container library is very almost finished. Since the review, the following major changes has been made - improved docs with new tutorial and improved browsing - new indirect functions - new Cloneable and Clone Allocator concepts - support for null values - refactored template interface off all classes - implementation guarantees to only instantiate std::container<void*> - rewritten iterators - improved tests The new docs, and code can be downloaded from the files section: http://groups.yahoo.com/group/boost/files/pointer%20container/ptr_container… The test runs with vc7.1 and gcc.3.3.3. Comments, suggestions and portability fixes are welcome. There are one major issue and one minor I need to have resolved during the post-review. Minor issue: allocation in map:operator[] ---------------------------------------- should a default allocated object use operator new or heap_clone_allocator::allocate_default(); ? This happens in ptr_map<string,int> m; m["foo"] = 5; // will allocate an int with new Normally the use can control all allocations because he always add objects manually or via cloninin (which he also controls). But the default object is just allocated with operator new inside ptr_map::operator[]. Should some hook be provided in a new allocator concept, map_heap_allocator? Major issue: ptr_iterator implementation. ----------------------------------------- So what is the problem? Well, since void* is used internally, the iterators must cast to the proper type in operator*; that is no problem for the default indireted iterators; the problem is with the iterators from ptr_iterator ptr_begin(); ptr_iterator ptr_end(); One way to define would be to say typedef internal_container::iterator ptr_iterator; Then the reference type would be void*& and not T*& as we would like. So if the user wanted to sort the container, he would do std::sort( cont.begin(), cont.end(), void_ptr_indirect_fun< std::less<T>, T>() ); This give us a rather insecure interface where you have to cast manually to T* inside the functor. So I wish we could get a T*& reference type. I think, from discussion with David Abrahams, that the current implementation is non-portable even though my test works: typedef T*& reference; reference dereference() const { // void_type is void* or const void* // I'm not sure why this is needed, but it seems to be return reinterpret_cast<reference>( const_cast<void_type&>( *iter_ ) ); } Does anybody knows how to rewrite this crappy code propoerly? I think we're faced with three options 1. keep the current behavior and describe in the docs that it is non-portable 2. go back to making ptr_iterator the default iterator with void*& reference type; 3. add a small subset of algorithms to the classes themselves; I'm thinking that the subset from std::list is appropriate: - sort - remove_if - remove - unique - reverse - merge Let me hear what you think best regards -- Thorsten Ottosen ---------------------------- www.dezide.com www.cs.aau.dk/index2.php?content=Research/bss www.boost.org www.open-std.org/JTC1/SC22/WG21/

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[FSM library] review result: accepted with few conditions
by Pavel Vozenilek 20 Mar '05

20 Mar '05

FSM library written by Andreas Huber has been accepted into Boost, with few conditions and few recomendations. Thanks, Andreas, for your work and stamina to get thus far! Also thanks to all courageous reviewers. Short overview: =============== Opinions of reviewers were mixed. Large group liked the library, some even used it in production code. Other large group had objections Most questioned were performance and API. At the end my opinion is: no single perfect fit exists so it makes little sense to dismiss this library waiting for a hypothetical everyone-is-happy solution. Other variant was to ask for changes and for second review later. FSM is mature, has been developed for years and will be maintained in the future: its not likely such solution would make much of good for end result. Conditions: 1. Name of the library should be changed: - not to suggest that only one FSM implementation may exists in Boost - not to give wrong impression to people who look for tool with maximal runtime efficiency. - to stress the "high-level" nature of the library Names suggested during review were Statechart (by Alexander Nasonov) and umlfsm. 2. Information about performance overhead should be separated into page of its own and made clearly visible. Recomendations: 3. API of the library should be simplified as much as possible. Quirks and dangerous situations should be eliminated as much as possible. 4. The documentation should be improved as much as possible. 5. Runtime overhead should be decreased as much as feasible but without sacrifying currently available features of the library. Detailed information: ===================== 1. Name of the library should include change of namespace as well. 2. The information about runtime overhead. Separate page should be created and made visible on front page. It should contain examples of applications where FSM may not be the best solution (e.g. parsers). 3. API of the library, quirks and features. People asked many ways to simplify the API and increase orthogonality of its features: - the danger in using transit<> should be eliminated (Jonathan Turkanis suggested way how to do it) - the syntax to add deferred event should be cleaned up, even it it adds overhead - similarly posting events from inside FSM: if there's chance to make its syntax easier it should be done (no matter what IMHO) - reducing # of template parameters for state, possibly putting reactions as typedef inside state - it was suggested (by Daryl Green) to deduce reaction-list by examination of class interface - polymorphic events may be added for completeness (Peter Petrov found workaround but it may be better to do it right) - add handling of unknown events - custom allocator for FSM used for all states constructed in it. Perhaps it is possible to detect presence of overloaded operator new in state and it if doesn't exist then use state_machine allocator - not using containers keeping historical data when history feature is not used - possibility to use flyweight classes for states or class factories to create states - eliminate need for mpl::list for history parameter - description of transition guards in header was requested (perhaps it may be optional feature) Whether the library should separate its asynchronous part out was not discussed much. I guess it is better to keep it in and possibly submit it as standalone library. 4. Documentation. Among suggested improvements were: - better indentation in code snippets, inlined comments, syntax highlighting - adding complete examples to code snippets so users can try immediatelly - more information for error handling and asynchronous FSMs - reduce the radius of big black dots for initial states - external documents describing UML mapping should be more visible - avoiding forward declarations of events in code snippets - more examples (e.g. half-adder used twice to create a full-adder, suggested by Dave Gomboc, combination of synchronous and asynchronous machines) The documentation is now very dense, splitting it into smaller parts may help. More hyperlinking would also help a lot. The documentation may contain page "How to" with tricks, workarounds and non-obvious examples of use. For example how to use nested state to keep data related to inner states. I think adding UML and/or FSM tutorial in documentation is not task if this library. 5. Runtime overhead. Best effort should be made but only after stabilizing features and API. Reducing executable code size (per state/transition) may be the first direction here. ------------------------------- I hope that alternative FSM implementations (like the one currently developed by Alexander Nasonov) or dynamic FSM will appear and will be submitted to Boost as well. /Pavel

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[fsm] Outstanding answers to review questions
by Andreas Huber 20 Mar '05

20 Mar '05

It seems I have finally managed to answer all the questions. In case someone is still waiting for answer, please let me know. Thanks & Regards, -- Andreas Huber When replying by private email, please remove the words spam and trap from the address shown in the header.

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