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[iterator + lambda] transform_iterator and lambda expression
by Vladimir Prus 04 Jun '04

04 Jun '04

I'm again trying to use FP in C++, and having problems. What I wanted to do was: for_each(predecesor(v, g), /* BLL expression */ ); where predecessor(..) returns a pair of 'transform_iterator' instances. The simplest example which illustrates the problem is: struct functor { typedef int result_type; int operator()(int i) const { return i+1; }; }; transform_iterator<functor, vector<int>::iterator> it(v.begin()); (cout << _1)(*it); This does not compile, because operator* of transform_iterator return rvalue which can't be bound to non-const reference that operator() of the lambda expression accepts. Of all workarounds suggsted on BLL docs, only break_const is applicable to my case (I want to pass non-const references to the lambda, so const_parameters won't do), and break_const is scary. It looks like a serious problem with using FP, so I wonder what can be done. Maybe, transform_iterator should have yet another template parameter telling if it should store a value internally, and return reference (i.e. lvalue) in that case? It need not be enabled by default, but functions like my 'predecessor' above would make use of that extra template parameter. - Volodya

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Re:[boost] A question on serialization library
by Robert Ramey 04 Jun '04

04 Jun '04

Virendra Verma wrote: > If a class has a pointer to an object, how does class know that the > pointer was created by library or the class itself before serialization? It doesn't. Why would it need to? Robert Ramey

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transform_iterator( Iterator const& x ) ???
by David Abrahams 04 Jun '04

04 Jun '04

I'm not sure why I never saw this on the list, but since I saw the moderation request and I figure you deserve a reply... boost-owner(a)lists.boost.org writes: > From: "Sascha" <vudu(a)gmx.net> > Subject: boost::transform_iterator( Iterator const& x ) ??? > To: <boost(a)lists.boost.org> > Date: Thu, 3 Jun 2004 00:22:18 +0200 > > hi > > a simple question about the construction of > boost::transform_iterator. > > currently there are two ctors implemented: > > transform_iterator(); > transform_iterator(Iterator const& x, UnaryFunction f); > > why does boost::transform_iterator(Iterator const& x) not exist leaving > the function object default constructed? Are you looking at the source code or the documentation? Oh, I see you're doing as you should and looking at the documentation! Well it turns out that the source code actually contains this constructor: explicit transform_iterator(Iterator const& x) : super_t(x) { // don't provide this constructor if UnaryFunction is a // function pointer type, since it will be 0. Too dangerous. BOOST_STATIC_ASSERT(is_class<UnaryFunction>::value); } > can I add it without getting in trouble? No, but we can fix the documentation ;-) -- Dave Abrahams Boost Consulting http://www.boost-consulting.com

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[Boost-bugs] [ boost-Bugs-966496 ] [BGL] Asymmetry between read_graphviz() and write_graphviz()
by SourceForge.net 04 Jun '04

04 Jun '04

Bugs item #966496, was opened at 2004-06-04 06:02 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=966496&group_i… Category: graph Group: None Status: Open Resolution: None Priority: 5 Submitted By: Nobody/Anonymous (nobody) Assigned to: Jeremy Siek (jsiek) Summary: [BGL] Asymmetry between read_graphviz() and write_graphviz() Initial Comment: During some experiments with the BGL-GraphViz interface, I observed a significant asymmetry between a given DOT graph input with boost::read_graphviz() and output with boost::write_graphviz() (without changing any attributes). Given the input DOT file <metro.dot> (which is, of course, much longer with the full set of information), the elementary BGL program <metro.cxx> transforms this into the output DOT file <metro_boost.dot> (the three files are attached to this submission). It seems that somewhere on the way, the graph and node (and edge) attributes get clobbered. Note that even the graph name "metro" gets replaced by the name of the (last) subgraph "ligne_1", and /all/ node attributes get mixed up. This seems to be somewhat similar to the recent edge-related problem posted by Hideaki Hiraki to the boost-users list. I have not (yet) tried to mess with the graphviz parser code, so I am asking here for help. Thanks. Greetings, Andreas <andreas dot scherer at rb-its dot de> ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=966496&group_i… ------------------------------------------------------- This SF.Net email is sponsored by the new InstallShield X. >From Windows to Linux, servers to mobile, InstallShield X is the one installation-authoring solution that does it all. Learn more and evaluate today! http://www.installshield.com/Dev2Dev/0504 _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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BOOST_NO_STDC_NAMESPACE and LIBCOMO
by Robert Ramey 04 Jun '04

04 Jun '04

Commeau I'm building with como-win32 with the libcomo library. It seems that BOOST_NO_STDC_NAMESPACE is set to true with this combination and that it should be set to false for this combination. Robert Ramey

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RE: [boost] Re: Re: Re: Boost Mathematicians
by Hurd, Matthew 04 Jun '04

04 Jun '04

> Behalf Of Thorsten Ottosen > > > "Hurd, Matthew" <hurdm(a)sig.com> wrote in message <snip> > See Type-Based Alias Analysis: > > http://www.ddj.com/documents/s=880/ddj0010d/0010d.htm?temp=fXniOPb1aS Thanks for the link. > > I my suggestion for Design by Contract I mentioned that aliasing (or lack of > it) > could be expressed by a function precondition: > > void foo( T* l, T* r, size_t sz ) > precondition() { > std::less<T*>( l + sz, r ) || std::less<T*>( r + sz, l ); > }; That's ok for simple contiguous spaces but it becomes intractable with complex object collections, but then perhaps the efficiency probably ain't so important as you've lost the locality anyway. > | You still need to wrap as you can't hope, nor should you try, to offer > | all algorithms from all languages. > > probably not. But simply wrapping stuff is not always an option. For eaxample, > in the > statistics lib I'm working on, I need to invert matrices. If I write wrappers, > I will > probably only be ably to support float,double,complex leaving out higher > precsion > datatypes. Yup. Generic interface first. Implementation with ublas where possible. Other generic implementations. Specialize for performance I guess. I haven't looked at uBLAs for a while but there was an interface to ATLAS for performance and also a partial wrapper for LAPACK. Not sure if the use of ATLAS or otherwise is or can be made to be automatic at compile time, but this would give us most of what we need. Generic implementations with pluggable special high performance specializations wherever possible. Regards, Matt Hurd. _______________ Matt Hurd +61.2.8226.5029 hurdm(a)sig.com Susquehanna _______________ IMPORTANT: The information contained in this email and/or its attachments is confidential. If you are not the intended recipient, please notify the sender immediately by reply and immediately delete this message and all its attachments. Any review, use, reproduction, disclosure or dissemination of this message or any attachment by an unintended recipient is strictly prohibited. Neither this message nor any attachment is intended as or should be construed as an offer, solicitation or recommendation to buy or sell any security or other financial instrument. Neither the sender, his or her employer nor any of their respective affiliates makes any warranties as to the completeness or accuracy of any of the information contained herein or that this message or any of its attachments is free of viruses.

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RE: [boost] Proposed Boost Library for Data Series Analysis
by Hurd, Matthew 04 Jun '04

04 Jun '04

> Behalf Of Tom Brinkman > Sounds very powerful. Is there any additional web > information to help me incorporate > these ideas. Not that I know of, but it isn't overly original in approach. Most interactive tools, such as a spreadsheet, will have something like a DAG structure at their core to represent a model-view type dependency thingo. Wish I had more time to play with this stuff... Regards, Matt Hurd. _______________ Matt Hurd +61.2.8226.5029 hurdm(a)sig.com Susquehanna _______________ IMPORTANT: The information contained in this email and/or its attachments is confidential. If you are not the intended recipient, please notify the sender immediately by reply and immediately delete this message and all its attachments. Any review, use, reproduction, disclosure or dissemination of this message or any attachment by an unintended recipient is strictly prohibited. Neither this message nor any attachment is intended as or should be construed as an offer, solicitation or recommendation to buy or sell any security or other financial instrument. Neither the sender, his or her employer nor any of their respective affiliates makes any warranties as to the completeness or accuracy of any of the information contained herein or that this message or any of its attachments is free of viruses.

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RE: [boost] [assignment library post review]
by Rozental, Gennadiy 04 Jun '04

04 Jun '04

> The post review version can be downloaded from > http://tinyurl.com/38c7d Could you please clean archive from garbage in test directory. Gennadiy.

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RE: [boost] [assignment library post review]
by Max Khesin 04 Jun '04

04 Jun '04

Thorsten, link's dead. > -----Original Message----- > From: Thorsten Ottosen [mailto:nesotto@cs.auc.dk] > Sent: Thursday, June 03, 2004 1:08 PM > To: boost(a)lists.boost.org > Subject: [boost] [assignment library post review] > > > Dear All, > > The post review version can be downloaded from > > http://tinyurl.com/38c7d This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail.

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Proposed Boost Library for Data Series Analysis
by Tom Brinkman 04 Jun '04

04 Jun '04

I've created a library for data series calculation and analysis. I've received permission to open-source the library and I would like to submit it for review to the boost if there is sufficient interest. Simple Example 1: Calculate the 10-day simple-moving-average of the 15 exponential-moving-average. (Demonstrates: boost::algorithm::compose). std::vector<double> v1; v1 += 3,4,4,6,7,8,4,7,8,3,2,3,2,5; typedef boost::algorithm::compose<double, boost::function<double (double)>, boost::function<double (double)> > COMPOSE; std::vector<double> v; std::transform(v1.begin(), v1.end(), std::back_inserter(v), COMPOSE(moving_average(15), exponential_moving_average(10))); Simple Example 2 (contrived): * Add 100 to the results from above. * then divide by 100, * then subtract by 100, * then multiply by 100. std::vector<double> v1; v1 += 3,4,4,6,7,8,4,7,8,3,2,3,2,5; typedef boost::algorithm::compose<double, boost::function<double (double)>, boost::function<double (double), boost::function<double (double), boost::function<double (double)> > COMPOSE2; std::vector<double> v2; std::transform(v.begin(), v.end(), std::back_inserter(v2), COMPOSE2(_1 += 100, _1 /= 100, _1 -= 100, _1 *= 100)); Here is a paritial list of functors currently provided by the library. Many additional functors have been written but are fairly specific to our problem domain. moving_average triangle_moving_average rate_of_change momentum vertical_horizontal_filter volatility weighted_moving_average exponential_moving_average variable_moving_average accumulate_n relative_strengh_index cumulative_sum max_numeric_limit variance standard_deviation correlation z_score Please tell me if there is any interest in this library. I will boostify it and submit it for review if there is sufficient interest. Regards, Tom Brinkman __________________________________ Do you Yahoo!? Friends. Fun. Try the all-new Yahoo! Messenger. http://messenger.yahoo.com/

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