July 2015 - Boost - lists.boost.org

A GUI Library
by jinhao 09 Nov '17

09 Nov '17

Hi, all I am developing a GUI library, it takes aim at easy-to-use and portable library for modern C++ methods. The project at http://stdex.sourceforge.net A git repository at http://nanapro.codeplex.com A brief at http://nanaproject.wordpress.com/2011/12/16/preliminary-study-of-nana-c-lib… Is there any interest in this library? Regards Jinhao

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Re: [boost] Boost CRC maintainer (Daryle Walker) missing in action?
by Olaf van der Spek 19 Jun '17

19 Jun '17

Hi Daryle, Any luck on your new setup? Gr, Olaf On Mon, Nov 28, 2011 at 1:11 AM, Daryle Walker <darylew(a)gmail.com> wrote: > I can look at it once I've finished my new setup. > > I had to reset my computer after a partial crash years ago. I never > got around to recreating my programming setup. My computer had been > at its maximum Operating System level back then, which is now 3 > versions behind. For the past few months, I've had my sister's old > laptop, with Windows Vista, and am trying to add a programming setup > to it now. > > > On Tue, Nov 22, 2011 at 7:18 AM, Beman Dawes <bdawes(a)acm.org> wrote: >> Hi Daryle, >> >> This guy has volunteered to take over maintenance of Boost CRC. Should >> we take him up on his offer? > >> ---------- Forwarded message ---------- >> From: >> Date: Wed, Nov 2, 2011 at 7:51 AM >> Subject: [boost] Boost CRC maintainer (Daryle Walker) missing in action? >> To: boost(a)lists.boost.org >> >> >> Hi, >> >> It looks like the Boost CRC maintainer (Daryle Walker) is missing in action? >> >> No response to tickets from the past 3 years. What's the procedure in this case? >> >> https://svn.boost.org/trac/boost/ticket/2492 >> https://svn.boost.org/trac/boost/query?component=crc&col=id&col=summary&col… > > -- > Daryle Walker > Mac, Internet, and Video Game Junkie > darylew AT gmail DOT com -- Olaf

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bad include guards
by Steven Watanabe 26 Jan '17

26 Jan '17

AMDG The following pairs of files have identical include guards ./boost/concept_check/general.hpp ./boost/concept/detail/msvc.hpp ./boost/concept_check/msvc.hpp ./boost/concept/detail/msvc.hpp ./boost/filesystem/cerrno.hpp ./boost/cerrno.hpp ./boost/interprocess/containers/tree.hpp ./boost/interprocess/containers/detail/tree.hpp ./boost/mpl/min_max.hpp ./boost/mpl/max.hpp ./boost/mpl/vector/aux_/front.hpp ./boost/mpl/list/aux_/front.hpp ./boost/multi_index/identity_fwd.hpp ./boost/multi_index/identity.hpp ./boost/python/pointee.hpp ./boost/python/detail/pointee.hpp ./boost/spirit/phoenix/closures.hpp ./boost/lambda/closures.hpp ./boost/xpressive/proto/v1_/proto_typeof.hpp ./boost/xpressive/proto/proto_typeof.hpp ./libs/config/test/boost_no_dep_nested_class.ipp ./libs/config/test/boost_has_vc6_mem_templ.ipp ./libs/config/test/boost_no_mem_templates.ipp ./libs/config/test/boost_has_vc6_mem_templ.ipp ./libs/config/test/boost_no_std_allocator.ipp ./libs/config/test/boost_has_vc6_mem_templ.ipp ./libs/conversion/test.hpp ./libs/any/test.hpp ./libs/interprocess/example/print_container.hpp ./libs/interprocess/example/printcontainer.hpp ./libs/interprocess/test/expand_bwd_test_template.hpp ./libs/interprocess/test/allocation_test_template.hpp ./libs/interprocess/test/printcontainer.hpp ./libs/interprocess/example/printcontainer.hpp ./libs/interprocess/test/print_container.hpp ./libs/interprocess/example/printcontainer.hpp ./libs/iostreams/test/detail/utf8_codecvt_facet.hpp ./boost/detail/utf8_codecvt_facet.hpp ./libs/regex/test/regress/test_regex_search.hpp ./libs/regex/test/regress/test_partial_match.hpp ./libs/serialization/test/C.hpp ./libs/serialization/test/A.hpp ./libs/xpressive/perf/regex_comparison.hpp ./libs/regex/performance/regex_comparison.hpp ./tools/inspect/time_string.hpp ./tools/common/time_string.hpp In Christ, Steven Watanabe

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[multiprecision] uses boost::math::gcd without including the header
by Peter Dimov 04 Jan '16

04 Jan '16

include/boost/multiprecision/cpp_int/misc.hpp uses boost::math::gcd (and lcm), but does not include common_factor_rt.hpp.

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[variant] Opinion on boost::safe_get<> and default boost::get<> behavior
by Antony Polukhin 18 Dec '15

18 Dec '15

Hi all, I'm in doubt and would like to hear opinions on the following issue. boost::get for boost::variant was not making any compile time checks, resulting in runtime errors where a compile time error must be: boost::variant<int, string> v(100); boost::get<bool>(&v); // returns NULL instead of compile time error boost::get<bool>(v); // throws exception on runtime instead of compile time error Now we have an implementation of compile time checked get in a separate branch at git: boost::variant<int, string> v(100); boost::safe_get<bool>(&v); // compile time error boost::safe_get<bool>(v); // compile time error boost::unsafe_get<bool>(&v); // returns NULL instead of compile time error boost::unsafe_get<bool>(v); // throws exception on runtime instead of compile time error I'm in doubt, what the default behavior of boost::get must be: * safe_get behavior is much closer to Standard Library behavior (just like std::get for tuples) and allows to avoid errors in user code * unsafe_get behavior is same as behavior of old boost::get and won't break user's code if boost::get is used in some generic contexs What's your opinion? -- Best regards, Antony Polukhin

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[thread] Do we can a non backward compatible version with non-blocking futures?
by Vicente J. Botet Escriba 18 Oct '15

18 Oct '15

Hi, in Boost 1.58 I fixed some issues as the result of the async and future<T>:then() was not a blocking future as the documentation described. However the implementation is horrible and I suspect that it is subject to deadlocks. BTW, I added already some fixes on the develop branch. Sometime ago I started in a branch an implementation that don't use blocking futures [1]. Well the implementation is also horrible after making futures non-blocking, but less ;-) The problem is that now I have some issues with the executors :( Anyway, Gor has told me that with the blocking implementation he is unable to define await_suspend (using resumable functions) >It is just if .then returns a blocking future, I cannot subscribe a callback to .then in await_suspend. >await_suspend(f, cb) { > f.then(cb); >} &will block here preventing coroutine from suspending I don't know yet if he will reach to configure boost::future<T> on the non-blocking branch. My question is if the Boost community will accept (or even wants) a breaking change on a near release (when I would reach to fix the executors issues) including non-blocking futures instead of the current blocking futures. Best, Vicente [1] https://github.com/boostorg/thread/tree/feature/non_blocking_futures

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[WG21 mailing] N4453 Resumable expressions
by Niall Douglas 15 Oct '15

15 Oct '15

I'm finding Chris' paper on resumable expressions instead of compiler magic created resumable functions awfully compelling: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4453.pdf I essentially proposed the same with my functionally composed constexpr basic_future design some months ago. Would anyone else like to comment on this library based instead of compiler based resumable execution? I'm not against some compiler support for resumable execution, but I am finding the await based proposal highly problematic, and Chris does an excellent job in summarising my own thoughts on what's wrong with it. Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/

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Re: [boost] [afio] AFIO review postponed till Monday
by Glen Fernandes 29 Aug '15

29 Aug '15

Did the review start yesterday? Glen

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"Simple C++11 metaprogramming"
by Peter Dimov 22 Aug '15

22 Aug '15

I've recently made the mistake to reread Eric Niebler's excellent "Tiny Metaprogramming Library" article http://ericniebler.com/2014/11/13/tiny-metaprogramming-library/ which of course prompted me to try to experiment with my own tiny metaprogramming library and to see how I'd go about implementing tuple_cat (a challenge Eric gives.) Ordinarily, any such experiments of mine leave no trace once I abandon them and move on, but this time I decided to at least write an article about the result, so here it is, with the hope someone might find it useful. :-) http://pdimov.com/cpp2/simple_cxx11_metaprogramming.html

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[filesystem] proposal: treat reparse files as regular files
by Paul Harris 14 Aug '15

14 Aug '15

Hi all, -- Proposal -- tl;dr : I propose that we treat all non-symlink "reparse_files" as "regular_files". If the boost library user wants to do something special with these plain reparse files, they should use alternative means. But typically they are supposed to be treated as regular files. This means we could drop the "reparse_file" enum, or continue to use it for a special-case whats_my_real_status() function. --- Motivation --- Windows Server 2012 uses reparse points to implement deduplification. Those files should be treated as regular files in all circumstances. Currently, they are not classed as "regular" files, so fs::copy() will skip those files, and library-user code written to list files based on official examples will ignore all dedup'd files. This is causing serious and latent problems at the user end, because deduping only happens occasionally after X days, and users cannot easily check if a file is dedup'd (they look just like regular files). --- Real life example --- Another example of reparse use is the "Symantec Enterprise Vault" (version 10), which I found running on one site. It replaces files on the server with reparse-point files. FSUTIL REPARSEPOINT QUERY filename.txt shows the contents of the reparse buffer, which is a URL to an internal HTTP server. The url points to a .asp link with a bunch of codes and dates to identify the file in the server. Copy-pasting that URL into a webbrowser allows you to directly download the file via the webbrowser, which is pretty neat I suppose. In this case, the reparsed-files in Windows Explorer all have grey X crosses on their file icon. If you "type" them (via cmd) or open them, the icon loses the grey cross and the file is no longer a reparse point file. My software refused to read the files because they were "not regular files". Once I adjusted the boost code (described below), my software saw them as regular and opened the files. The file icons lost the grey cross. SO it seems that the file server automatically downloads and replaces the files with the stored content on demand, and the file reading client program should really just treat these files as normal files. --- Short logic --- reparse files (that are not symlinks) should almost always be treated as plain files. They are a mechanism for MS file servers to store files in clever ways, but the client should not care and just read/write them as if they were normal files. This is different to all the other "other" files which can't be treated like normal files: block, character, fifo, socket, unknown So, reparse files should not be grouped with the "other" file types. They are also NOT symlinks, and should not be treated as symlinks (which would require special decisions for copying, or querying the status, or checking if the target still exists). --- What are reparse files --- I did some reading, if I understand correctly: Reparse points give drivers (on the server) a chance to get data through some other specialised means (eg query from a cluster store). They are processed by the server, not the client, so clients should treat reparse data as opaque data. EXCEPT for symlink reparse files. https://msdn.microsoft.com/en-us/library/dd541667.aspx quote:"The following reparse tags, with the exception of IO_REPARSE_TAG_SYMLINK, are processed on the server and are not processed by a client after transmission over the wire. Clients should treat associated reparse data as opaque data." It seems like the rest of the tags are used for connecting files to other types of storage (eg long term storage, cluster storage). Clients may need to do something special with SOME reparse point files, IF the client cares about how long the file read may take. https://msdn.microsoft.com/en-us/library/windows/desktop/aa365505(v=vs.85).… quote: "Most applications should take special actions for files that have been moved to long-term storage, if only to notify the user that it may take a while to retrieve the file." --- Changes required --- Option 1: change is_regular_file() to return true where type==reparse_file I don't like this option, as library-users could be checking the type directly instead of using is_regular_file(). Option 2: These functions return reparse_file: fs::file_type query_file_type(const path& p, error_code* ec) file_status status(const path& p, error_code* ec) file_status symlink_status(const path& p, error_code* ec) They should instead return regular_file instead. --- How to test with dedup files --- Creating dedup'd files is a feature only available on Windows Server 2012, I believe, although Windows XP/Vista/7/8/10 clients all can read dedup files. Here is how I created a windows server to test with (for free!) on a demo Azure cloud server. I have one working, so if anyone would like to use it for their testing, let me know. Step one: follow this blog article: http://blogs.technet.com/b/tommypatterson/p/azureservertrial.aspx once the machine was "running" I clicked Connect at the bottom. That gave me an .rdp file which in theory I could use with rdesktop, but it uses a DNS name that was only just created, so that didn't work. When you click the name of the server in the list, it shows the public IP on the right.. and the port then you can do this $ rdesktop that.ip.addr:port But only if you have the latest rdesktop AND you have set up kerberos something-something. Instead I found a windows computer and used remote desktop from there. --- Once inside, in the "Server Manager --> Dashboard" window on the screen, click "Add Roles" then go next next until "Server Roles" expand "File and Storage services" , "File and iSCSI" , and tick "Data Deduplication" Then next next etc and Install. Wait a bit... and its done. http://www.techrepublic.com/blog/data-center/configuring-windows-server-8-d… --- Continuing on that webpage... Time to enable dedup. There is a temp disk D: so lets enable there. Method 1... I did this and then went to method 2... Start PowerShell, type: "Enable-DedupVolume D:" Method 2... in that same Dashboard, hit the 4th button (File and Storage Services) Then Volumes --> Disks click Volume 1 at the top, and then right click D: at the bottom --> Configure Dedup. To try and accelerate this puppy, I set the "age to dedup" to 0 days. http://www.techrepublic.com/blog/data-center/windows-server-2012-deduplicat… --- Time to make something to dedup. We'll just duplicate the warning.txt file that exists on D: In powershell: PS> D: PS> $file = Get-Content DATALOSS_WARNING_README.txt Then, do these 2 commands a bunch of times until "big.txt" gets to say 6MB PS> Add-Content big.txt $file PS> $file = Get-Content big.txt Then use windows explorer (or other) to make a dozen copies of big.txt Copy c:\windows\explorer.exe to D: to give it something to dedup Go to D: and then copy-paste explorer.exe a dozen times. In PowerShell, type: PS> Update-DedupStatus -Volume D: PS> Start-DedupStatus -Type Optimization -Volume D: and then wait for it to finish. you can track its progress with: PS> Get-DedupJob PS> Get-DedupStatus -Volume D: --- So, once its deduped, you check. PS> FSUTIL REPARSEPOINT QUERY big.txt you should see that its a reparse point with that 0x800etc0013 code. Copy-paste big.txt to big2.txt and check it with the query, and it should tell you big2 is NOT a reparse point. NOW you have some files to test the boost library... You can't zip them up (they lose the dedup tag), you have to run boost binaries ON the computer in the sky. --- Finish --- Thanks for reading, Paul

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