January 2015 - Boost - lists.preview.boost.org

Road to low-quality-code is paved with good intentions of dropping dependencies
by Antony Polukhin 09 Jan '15

09 Jan '15

Hi all, I've been looking through the latest changes to drop dependencies. Stuff that I saw is very frightening. For example: https://github.com/boostorg/move/blob/develop/include/boost/move/detail/typ… . Every boost release some issues are fixed in intrinsics of TypeTraits and is_move_* is_nothrow_* traits. Copy-pasting code from TypeTraits feels like loading a gun and pointing it on own foot. Another example is a sad story of boost::swap. We can not use Boost.Move here because it will add "a lot of dependencies" to Boost.Core. This leads us to nonoptimal implementation, which is sad. The Solution Almost *all* of the Boost libraries depend on TypeTraits, MPL, Core, Assert, StringRef. Language emulation features implemented in Exception, Move, StaticAssert, TypeIndex should be also widely used. hash_fwd.hpp must be used by almost all the containers and structures. So may be we should think of those libraries as of "base" libraries! I do not mean that they must be moved in a single "base" folder. I'm talking only about dependency reports: those libraries must be treated by the dependency tool as a single one and must have the level 1. Those libraries are "base", because they are the very common part of Boost framework. Not using them is more like a bad decision, reimplementing parts of them is an afwull decision. Threating them as base/common/core/main part of Boost seems reasonable. -- Best regards, Antony Polukhin

15 34

[bpm] Option to skip test dependencies?
by Beman Dawes 09 Jan '15

09 Jan '15

In looking at the Boost Package Manager [bpm] options, there is one omission I suspect users will ask for right away: an option to skip dependencies created by tests and perhaps examples. Is it possible to experiment with some simple strategy, like skipping the dependency check for "test" libraries to see what effect this has? Thanks, --Beman

2 1

ATTN library maintainers: libraries missing metadata files
by Peter Dimov 08 Jan '15

08 Jan '15

The following libraries are currently missing the metadata file meta/libraries.json, which describes the library: libs/algorithm/meta/libraries.json does not exist libs/assign/meta/libraries.json does not exist libs/bimap/meta/libraries.json does not exist libs/compatibility/meta/libraries.json does not exist libs/detail/meta/libraries.json does not exist libs/disjoint_sets/meta/libraries.json does not exist libs/function_types/meta/libraries.json does not exist libs/graph_parallel/meta/libraries.json does not exist libs/icl/meta/libraries.json does not exist libs/iostreams/meta/libraries.json does not exist libs/locale/meta/libraries.json does not exist libs/local_function/meta/libraries.json does not exist libs/numeric/meta/libraries.json does not exist libs/parameter/meta/libraries.json does not exist libs/ptr_container/meta/libraries.json does not exist libs/python/meta/libraries.json does not exist libs/random/meta/libraries.json does not exist libs/range/meta/libraries.json does not exist libs/rational/meta/libraries.json does not exist libs/scope_exit/meta/libraries.json does not exist libs/serialization/meta/libraries.json does not exist libs/statechart/meta/libraries.json does not exist libs/sync/meta/libraries.json does not exist libs/typeof/meta/libraries.json does not exist libs/type_erasure/meta/libraries.json does not exist libs/uuid/meta/libraries.json does not exist libs/winapi/meta/libraries.json does not exist Many of those libraries already have pull requests that contain the file. Please accept them and then merge them to master as well. :-) The file format is documented here: http://www.boost.org/development/library_metadata.html

2 3

Boost.Sort library hierarchy and namespacing
by Steven Ross 08 Jan '15

08 Jan '15

For the Boost.Sort library, I'm planning to add these (non-detail) files: boost/sort/sort.hpp boost/sort/spreadsort/spreadsort.hpp boost/sort/spreadsort/integer_sort.hpp boost/sort/spreadsort/float_sort.hpp boost/sort/spreadsort/string_sort.hpp Should all of these be in the boost::sort namespace? It seems silly to have a boost::sort::spreadsort namespace when there are only 5 publicly-visible functions in it. I actually can't imagine how of these names will conflict with names in other boost libraries, but using a boost::sort namespace appears conventional. Are there any objections or concerns based on this? Once this is done, I'd like to integrate this library into the boost build and testing system for the next appropriate release (I test it currently with modular boost).

2 2

Directory structure not quite right yet?
by Peter Dimov 08 Jan '15

08 Jan '15

Typically, when some library is installed in, say, $LIB, its headers reside in $LIB/include and its .a/.lib files in $LIB/lib. Our libraries, when built, go to $BOOST/stage/lib, which is close enough. But our header directory is just $BOOST, which doesn't seem right, as the whole of Boost is accessible through it. It makes sense, at least to me, to have the headers in $BOOST/include/boost, instead of just $BOOST/boost. The transition to Git would have been a good time to switch to that - there were enough other changes to the structure. I'm not saying that we should switch right away or something like that, but am I the only one to whom such a switch (at some unspecified time in the future) seems a good idea?

12 41

Is TypeOf library maintained?
by Adam Wulkiewicz 08 Jan '15

08 Jan '15

Hi, I'm asking because the most recent change in develop was done in 2013 and the last merge to master (or rather SVN release) was done in 2011. Would it be possible to along with the metadata PR have this trivial fix merged: https://github.com/boostorg/typeof/pull/1 ? It hangs there more than a half year. Thanks, Adam

2 1

New dependency report
by Peter Dimov 08 Jan '15

08 Jan '15

Here: http://www.pdimov.com/tmp/report-develop-3b5a9f4/module-overview.html http://www.pdimov.com/tmp/report-develop-3b5a9f4/module-levels.html and (new) here: http://www.pdimov.com/tmp/report-develop-3b5a9f4/module-weights.html "Weight" is on how many other modules a module depends, both directly and indirectly.

1 0

[Tick] Universal quantified concepts/traits
by Vicente J. Botet Escriba 06 Jan '15

06 Jan '15

Hi, I'm trying to represent the concept of a mathematical Functor (as in Haskell) with Concept Lite. Here is what I want to express: A Functor W is a type constructor for wrappers of another type T providing a function map taking a function (T) -> U and a W<T> and returning a W<U>. Here is how I think that could be done with Concept Lite. If I understand the proposal correctly we need to add the type T and the function parameter to the concept. concept Functor<typename W, typename T, typename F > = requires { using WT = ApplyType<W, T>; // type constructor using U = ResultType<F, T>; using WU = ApplyType<W, U>; Function<F, U, T> && requires (F f, WT wt) { WU { map(f, wt) }; } }; But this is not exactly what I want to conceptualize. The wrapped type T and the function F should be universally quantified, that is, the concept concerns only the type constructor W: Functor<W>. I have a problem introducing the universal quantification of T and F. I don't know how to do it without using again a template. concept Functor<typename W> = template <typename T, typename F> // universal quantification on T and F requires { using WT = ApplyType<W, T>; using U = ResultType<F, T>; using WU = ApplyType<W, U>; Function<F, U, T> && requires (F f, WT wt) { WU { map(f, wt) }; } } }; But this is not valid code, isn't it. Is there something wrong with this kind of concepts? What would be the best way to conceptualize this kind of concepts with the Tick library ? Best, Vicente

3 5

bpm, a tool to install a modular Boost distribution
by Peter Dimov 06 Jan '15

06 Jan '15

One month ago, Stephen Kelly wrote: > git affects the developer workflow, but that thread was about creating > modular releases and downloads, which is a different goal and has a > different set of problems to solve. That's what that thread was about. I > didn't see any desire to have that as a goal in the thread. > > Git doesn't affect users. > > Before and after transition to git, they download all-of-boost.zip from > the boost website. To address this point of his, I've been working at a tool, bpm, that can install a modular Boost distribution. As I've already mentioned in other threads, it works like this: D:\boost-1.60.0>bpm install system bpm: installing module 'system' bpm: installing module 'assert' bpm: installing module 'config' bpm: installing module 'core' bpm: installing module 'predef' bpm: installing module 'build' bpm: the following libraries need to be built: system bpm: (use ./b2 to build) bpm: recreating header links bpm: recreating index That is, when told to install Boost.System, it downloads and installs the 'system' package into ./libs/system, along with all its dependencies, then creates links to the headers (like 'b2 headers') in ./include and an ./index.html file listing the installed libraries. The full syntax is: D:\boost-1.60.0>bpm Usage: bpm [-v] [-q] command [options] [modules] -v: Be verbose -vv: Be more verbose -q: Be quiet bpm install [-n] [+d] [-k] [-a] [-i] [-p] <module> <module>... Installs the specified modules and their dependencies into the current directory. -n: Only output what would be installed +d: Do not install dependencies -k: Do not remove partial installations on error -a: All modules (use instead of a module list) -i: Installed modules -p: Partially installed modules bpm remove [-n] [-f] [-d] [-a] [-p] <package> <package>... Removes the specified packages. (A package, like 'numeric', can contain more than one module.) -n: Only output what would be removed -f: Force removal even when dependents exist -d: Remove dependents as well. Requires -f -a: Remove all packages. Requires -f -p: Remove partially installed packages bpm list [-a] [-i] [-p] [-b] [prefix] Lists modules matching [prefix]. -a: All modules (default when no -b) -i: Installed modules (default when -b) -p: Partially installed modules -b: Modules that require building bpm headers Recreates the header links in the include/ subdirectory of the current directory. bpm index Recreates the file index.html, which lists the installed modules, in the current directory. -- This all works already under Windows. (I haven't finished the POSIX part yet but it should be close.) I could have made a Windows binary available for people to play with, but I'd rather give sources (at first). bpm contains code to do rm -rf <directory>, and if I've made a mistake somewhere, it could cause damage. So, if there is interest and there are no objections, I'd like to put this tool into the Boost repository, in tools/bpm.

5 10

[GIL] runtime assertion error
by Stephan Menzel 06 Jan '15

06 Jan '15

Hello, I was playing with GIL a little and started out with the tutorial. After adapting it a bit I noticed a runtime assertion error here in color_base.hpp +343: template <typename Element, typename Layout, int K> typename element_reference_type<homogeneous_color_base<Element,Layout,K> >::type dynamic_at_c(homogeneous_color_base<Element,Layout,K>& cb, std::size_t i) { assert(i<K); return (gil_reinterpret_cast<Element*>(&cb))[i]; } The example works if I compile in release but I still wanted to bring it up because of an extensive comment above this template that states that this assertion checks for compiler specific behavior and mentions flags that need to be set but not which flags. I believe there might be a bug there. Also, since it's the tutorial, I suppose it should work under most circumstances. I have a sample of the code attached. It's gcc 4.8 here in Linux 64. Nothing fancy. Boost 1.56. Cheers, Stephan

2 4