On 05/09/2017 08:21 AM, Igor Mironchik via Boost-users wrote:

2017-05-09 09:07, degski via Boost-users пишет:

...

On 9 May 2017 at 08:44, Igor Mironchik via Boost-users mailto:boost-users@lists.boost.org> wrote:

Is it possible?

Without specifying which library you are thinking of, no-one can answer that question other than by saying: "It depends".

I asked about such approach totally. But if there is no common answer - your answer is good enough for me. Thank you.

Hi Igor, Jens Weller once came up with a dependency analyzer of boost libraries. IIRC, one of his motivations was aligned to your request, i.e. finding which headers/libs a given boost library depends upon. For more information, see: https://meetingcpp.com/index.php/br/items/releasing-boost-dependency-analyze... as this post is from 2013, I am unclear what the current status of the project is. Best, P

Hi, Thank you for your replies. 2017-05-09 10:04, Asif Lodhi пишет:

It looks like you fear that all the boost libraries will get included in your final executable - that's not the case. Only the code that you call gets included - that's a function of C++ compiler tool chain. Including a header makes code from that library available to your own code. You can then use using declarations or using directives for scoping. Only the functions that you call get included.

No, I asked about it because I possibly will put part of Boost in the repo...

On 9 May 2017 at 11:21, Igor Mironchik via Boost-users mailto:boost-users@lists.boost.org> wrote:

2017-05-09 09:07, degski via Boost-users пишет:

...

On 9 May 2017 at 08:44, Igor Mironchik via Boost-users mailto:boost-users@lists.boost.org> wrote:

Is it possible?

Without specifying which library you are thinking of, no-one can answer that question other than by saying: "It depends".

I asked about such approach totally. But if there is no common answer - your answer is good enough for me. Thank you.

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-----Original Message----- From: Boost-users [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Paolo Bolzoni via Boost-users Sent: 09 May 2017 16:05 To: boost-users@lists.boost.org Cc: Paolo Bolzoni Subject: Re: [Boost-users] Cutting headers

Unfortunately it is a long standing problem, even Bjarne Stroustrup mentions it. http://www.stroustrup.com/bs_faq.html#boost

The interdependence of Boost libraries isn't a 'problem' - it may be an inconvenience, but is an unavoidable consequence of missing built-in language features and Boost's invaluable working for multiple platforms, targets and compilers and standard versions. Work has been done to minimize unnecessary interdependence, but it remains almost impossible to write any library without using some other libraries, as the dependency graphs show. There is nothing to stop users figuring out the subset of essential libraries, sometimes quite small, as others have commented. The downside is that keeping up-to-date may be tiresome. Enjoy! Paul --- Paul A. Bristow Prizet Farmhouse Kendal UK LA8 8AB +44 (0) 1539 561830

From: Boost-users [mailto:boost-users-bounces@lists.boost.org] On Behalf Of degski via Boost-users Sent: 10 May 2017 14:55 To: boost-users@lists.boost.org Cc: degski Subject: Re: [Boost-users] Cutting headers On 10 May 2017 at 11:36, Paul A. Bristow via Boost-users wrote: The interdependence of Boost libraries isn't a 'problem' - it may be an inconvenience, but is an unavoidable consequence of missing built-in language features and Boost's invaluable working for multiple platforms, targets and compilers and standard versions. In my opinion, supporting things like VC7.1 in boost is actually doing the world a dis-service. The CRT's that come with VC7.1 (f.e.) have severe, known (to black-hat hackers) security issues AND ARE NOT SUPPORTED BY Microsoft. Microsoft is clear about what is and what isn't supported. Boost should not support more than that. If one doesn't adopt this approach, the backlog (of mess from the past) will never be cleared and windows will forever be characterised as THE unsafe platform, which I think is un-warranted. When will boost stop supporting VC7.1 (and all the other out-dated stuff, VC8 etc etc)? Well I think that it is, slowly, by adding new libraries that say C++11, or even C++17 only. Some reasons for not trying to actively strip out C++very_old handling code are 1 Not gratuitously mucking up those who are stuck maintaining C++98 systems but want to use the latest Boost version (surely a good idea?). If they have security issues, *they* should fix them; current Boost will still work. 2 It isn’t good use of limited peoples time to do this. 3 There is a very big risk of collateral damage. If it ain’t broke, don’t fix it. In short, evolution, not revolution - that usually means bloodshed ;-) HTH Paul --- Paul A. Bristow Prizet Farmhouse Kendal UK LA8 8AB +44 (0) 1539 561830

On 5/10/2017 11:14 AM, Paolo Bolzoni via Boost-users wrote:

On Wed, May 10, 2017 at 10:36 AM, Paul A. Bristow via Boost-users wrote:

...

...

Unfortunately it is a long standing problem, even Bjarne Stroustrup mentions it. http://www.stroustrup.com/bs_faq.html#boost

...

The interdependence of Boost libraries isn't a 'problem' - it may be an inconvenience, but is an unavoidable consequence of missing built-in language features and Boost's invaluable working for multiple platforms, targets and compilers and standard versions.

I find this pattern all the time, so even if a bit out of topic I have to ask. Perhaps it is simply a language barrier. Since when knowing where a problem come from makes it less a problem? You essentially are saying: "Yes, that's the situation. Here why. So it's not a problem." The problem IS there, if it is unavoidable, or incredibly difficult to solve, or "solving it" means to "replace it with bigger problems", then it is fine and we live with it. But it does not mean that it's not a problem.

...

Work has been done to minimize unnecessary interdependence, but it remains almost impossible to write any library without using some other libraries, as the dependency graphs show.

True enough, but some interdipendency are a bit gratuitous. Doubly now that the standard language gives part of boost.

I wrote a library whose purpose was to reduce the dependence on a Boost library when the C++ standard equivalent library was available at compile time, while reducing to a minimum any difference in the code between using Boost or the C++ standard equivalent, but no one was interested. So essentially dependence on other Boost libraries, even when the C++ standard equivalent is available via the compiler implementation, was not seen as an issue by other Boost developers.

...

There is nothing to stop users figuring out the subset of essential libraries, sometimes quite small, as others have commented. The downside is that keeping up-to-date may be tiresome.

"Nothing stops users" is not even an argument. The problem is exactly (quoting Stroustrup) that "it [is] hard to pick and choose." Hard does not mean impossible.

Said that, I DO NOT mean at all to say: boost has the problem that the libraries are overly coupled and so do not use it. Quoting again "it is usually a really dumb idea to go and reinvent a wheel that boost already offers," what I mean is: it is infortunate and we have to deal with it. Just like with arrays that becomes pointers.

On 5/10/2017 5:54 PM, james via Boost-users wrote:

This is ok depending on what your definition of 'equivalent' is.

In my cxxd library 'equivalent' meant that the syntax was the "same", but not necessarily the implementation. However the same syntax normally means that the same result would be expected.

For example, if I have something like

#ifdef MY_USE_BOOST using UnorderedMap = boost::unordered_map<...> #else using UnorderedMap = std::unordered_map<...> #endif

my code will likely compile ok, but the runtime behaviour will be different when the key is of type int, for example, due to the different hashing algorithms used between boost (a static_cast) and MS's implementation (computes an actual hash).

While the implementation may dictate that one side or the other is faster or uses less memory, I hardly believe that the result of using UnorderedMap would be different in actual usage. That is not to say you might prefer one or the other based on speed or size considerations.

Was there ever an attempt to standardise the default hashing algorithms?

I do not know what this means. Is there not a std::hash implementation ? BTW, when you top post, rather than answering inline, it is very hard to know to what you are referring. That is why you are admonished not to top post on mailing lists.

On Wed, May 10, 2017 at 8:59 PM, Edward Diener via Boost-users mailto:boost-users@lists.boost.org> wrote:

On 5/10/2017 11:14 AM, Paolo Bolzoni via Boost-users wrote:

On Wed, May 10, 2017 at 10:36 AM, Paul A. Bristow via Boost-users mailto:boost-users@lists.boost.org> wrote:

Unfortunately it is a long standing problem, even Bjarne Stroustrup mentions it. http://www.stroustrup.com/bs_faq.html#boost http://www.stroustrup.com/bs_faq.html#boost

The interdependence of Boost libraries isn't a 'problem' - it may be an inconvenience, but is an unavoidable consequence of missing built-in language features and Boost's invaluable working for multiple platforms, targets and compilers and standard versions.

I find this pattern all the time, so even if a bit out of topic I have to ask. Perhaps it is simply a language barrier. Since when knowing where a problem come from makes it less a problem? You essentially are saying: "Yes, that's the situation. Here why. So it's not a problem." The problem IS there, if it is unavoidable, or incredibly difficult to solve, or "solving it" means to "replace it with bigger problems", then it is fine and we live with it. But it does not mean that it's not a problem.

Work has been done to minimize unnecessary interdependence, but it remains almost impossible to write any library without using some other libraries, as the dependency graphs show.

True enough, but some interdipendency are a bit gratuitous. Doubly now that the standard language gives part of boost.

I wrote a library whose purpose was to reduce the dependence on a Boost library when the C++ standard equivalent library was available at compile time, while reducing to a minimum any difference in the code between using Boost or the C++ standard equivalent, but no one was interested. So essentially dependence on other Boost libraries, even when the C++ standard equivalent is available via the compiler implementation, was not seen as an issue by other Boost developers.

There is nothing to stop users figuring out the subset of essential libraries, sometimes quite small, as others have commented. The downside is that keeping up-to-date may be tiresome.

"Nothing stops users" is not even an argument. The problem is exactly (quoting Stroustrup) that "it [is] hard to pick and choose." Hard does not mean impossible.

Said that, I DO NOT mean at all to say: boost has the problem that the libraries are overly coupled and so do not use it. Quoting again "it is usually a really dumb idea to go and reinvent a wheel that boost already offers," what I mean is: it is infortunate and we have to deal with it. Just like with arrays that becomes pointers.

On 5/9/17 10:23 AM, Niall Douglas via Boost-users wrote:

On 09/05/2017 17:14, Robert Ramey via Boost-users wrote:

...

On 5/8/17 10:44 PM, Igor Mironchik via Boost-users wrote:

...

Hello,

How can I cut specific library from Boost, if, for example, I don't want to place all Boost but only one library from Boost?

Is it possible?

I do this all the time. I just import specific headers and link to the particular libraries.

The only issue that arises is that some boost libraries use other boost libraries so I have to add some other headers/libraries to the application working set. We have tools for determining these secondary dependencies but for some specific technical reasons they aren't perfect. I just work out the dependencies by hand. It's a simple one time procedure that just consists in building the app adding missing pieces until it builds to completion.

A faster way could be to use https://pypi.python.org/pypi/pcpp to partially preprocess a Boost library and all its dependent headers into a single, self contained include file.

Hmmm - I was pretty skeptical that this would be helpful when I read this. I went to the cited page and checked out. It wasn't all that clear what this thing does and how to use it. I probably could figure it out if I had time to do so though. But I can't believe that using it would be simpler, faster or more effective than the procedure I just outlined above.

Niall