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Subject: Re: [boost] Getting started build section
From: David Abrahams (dave_at_[hidden])
Date: 2008-11-06 11:55:33

on Thu Nov 06 2008, Vladimir Prus <> wrote:

> On Thursday 06 November 2008 17:38:02 David Abrahams wrote:
>> on Thu Nov 06 2008, Vladimir Prus <> wrote:
>> > Dave,
>> > I am reading the getting started guide, and think some of the build
>> > instructions can be improved. I can do this myself, if we agree on
>> > the nature of the changes.
>> >
>> > For reference, I'm looking at:
>> >
>> >> >
>> > 5 Prepare to Use a Boost Library Binary
>> >
>> > I think the section title is too long-winded. "Prepare" does not even
>> > suggest any kind of building. And of course, we have many libraries,
>> > so saying "a ... Binary" is not accurate.
>> > Would "Building Library Binaries" be more to the point?
>> No. You may have used the installer.
> And what about "a ... Binary" being not accurate, given that there's
> lots of library binaries?

It *is* accurate. We're working on a single example, and to build/run
that example you need a library binary, and this section describes what
you need to do to prepare to use it.

>> > The installers supplied by BoostPro Computing will download and
>> > install pre-compiled binaries into the lib\ subdirectory of the
>> > boost root, typically C:\Program Files\boost\boost_1_37_0\lib\. If
>> > you installed all variants of the Boost.Regex binary, you're done
>> > with this step. Otherwise, please run the installer again and
>> > install them now.
>> >
>> > I can't understand what the second sentence say. If installer
>> > allows to install only some variants of Boost.Regex, then
>> > documentation should to request the user to run the installer
>> > again, and install the remaining ones. I can't fix this text
>> > without knowing what it means.
>> Umm, that's exactly what it means. There's nothing to fix.
> If you want to say that users should always install all variants of
> Boost.Regex, please say so.

That's not what I want to say.

> Instructing the user to run installer again, and then select all
> variants, seems to have no benefits over selecting all variants in the
> first place. Am I missing something?

People who know they don't need binaries based on earlier sections of
the document shouldn't be instructed to build and install them from the

>> > The last sentence of 5.2 and the first sentence of 5.2.1 essentially duplicate
>> > each
>> > other.
>> No; 5.2.1 makes it clear you'll be using bjam from the command-line and
>> explains its role in the process. For example, it's not just something
>> that sets up your environment or post-processes library files.
>> > Besides, bjam does not really drives Boost.Build (just like my car
>> > does not drive me, usually).
>> Umm, right. Lots of terms we use in CS don't map meaningfully onto
>> everyday objects. How would you characterize bjam's role in the system?
> I would not try, actually. For most users, bjam and Boost.Build are not
> independent projects, so saying that Boost.Build is invoked by typing
> bjam on the command line seems reasonable.

I was trying to make the distinction and relationship between bjam and
Boost.Build a little clearer. I think you may be forgetting the many
people who used to say, "I read all through the bjam documentation but I
can't figure out how to <do something that's Boost.Build functionality>"

>> > First, find the toolset corresponding to your compiler in the
>> > following table. The kylix should be removed from the table.
>> Have we dropped it?
> Years ago (the product is dead, nobody used the Boost.Build support either)


>> > "FreeScale" should be "Freescale".
>> Good point;
>> > This should also link to the list of toolchains in Boost.Build docs.
>> Exact link, please.


>> > 5.2.3 Select a Build Directory
>> > Boost.Build will place all intermediate files it generates while building into
>> > the build directory. If your Boost root directory is writable, this step isn't
>> > strictly
>> > necessary: by default Boost.Build will create a bin.v2/ subdirectory for that
>> > purpose in your current working directory.
>> >
>> > I suggest that this section be dropped. In describes a non-mainstream usage
>> > that is better be describe elsewhere.
>> Maybe, but the thing I worry about is that a suitable "elsewhere"
>> doesn't exist. People seem to expect the GSG to tell them all sorts of
>> things that perhaps should be in a Boost.Build guide. I think that's
>> because they are having a hard time making the jump to that documentation.
> If you add a link to Boost.Build command line, that's where --build-dir is documented:

IMO the description of build-dir there is unsuitable for a beginning
user who doesn't know what these terms really mean:

    "project roots"
    "Jamroot files"
    "declare project name"
    "the project name specified in Jamroot"
    "build dir specified in Jamroot"

That might be OK if --build-dir is a truly esoteric option that almost nobody
needs. Now that we put everything under bin.v2, that might be true. It
certainly wasn't true with BBv1, where targets were always built inside
project directories by default. I'd like to hear some other peoples'
opinions on whether it's still relevant.

>> > Likewise, building from a network drive is not
>> > a good idea.
>> Why? I know companies where people do that successfully.
> I presume this depends on exact network infrastructure and usage
> scenarios, but a couple of couple of 8-core servers compiling from
> network disk can bring down a decent storage solution quite easily.

I trust people to evaluate whether that's suitable for them. Most
people will indeed have the sources on a local disk.

>> > This section should also link to Boost.Build doc section about command line
>> > syntax.
>> Exact link, please.


>> > If the summary does not include any failed targets, your build is successful,
>> > and the library binaries can be found in the 'stage' directory.
>> "the 'stage' directory" is too imprecise. How will the reader find it?
> If no --stagedir option is given, the 'stage' directory is placed in
> boost source root and named 'stage', exactly. That's what I meant. In
> fact, this post is prompted by user report on boost-build that say we
> don't document --stagedir. The --stagedir is an option defined in
> Boost Jamroot, not in Boost.Build, so probably should be
> documented. Though relying on bjam --help output may be acceptable,
> too.

--stagedir and --build-dir are very similar. We should probably make the
same decision about documenting both of them.

>> > Otherwise,
>> > you can browse the output to see which libraries failed to build, and which
>> > compile errors were produced. You can also run bjam again, with the same
>> > option, to try compiling the failed files again.
>> >
>> > A the beginning of the build, you will be informed what functionality
>> > of C++ Boost libraries is disabled because of lack of required third party
>> > libraries.
>> I think lacking a 3rd-party library is not the only reason the functionality
>> might be disabled. Don't you need some environment variables set for
>> ICU, or something?
> Ok, not "lack", then:
> A the beginning of the build, you will be informed what functionality
> of C++ Boost libraries is disabled because the required third party
> libraries could not be found.

Personally I don't see how this improves on the text that I already
wrote covering this topic. Nobody has reported confusion about that

>> > You might want to check that you don't require the disabled
>> > functionality, and perform additional configuration (see individual libraries
>> > documentation).
>> >
>> >
>> > If it seems like the build system can't find your compiler and/or linker,
>> > consider setting up a user-config.jam file as described in the Boost.Build
>> > documentation.
>> Exact link please.


>> > This should have a link to Boost.Build section about configuration, not to the
>> > top-level
>> > docs.
>> I think you raise a number of good points above. Certainly I welcome
>> more participation from the Boost.Build team in ensuring a smooth
>> Getting Started experience. In particular, I think helping people
>> transition from the GSG to the Boost.Build documentation is crucial.
> I fully agree. Note that some of the links I gave above are to
> recently-updated sections, meant to give a relatively complete
> instructions to somebody who just wants to build boost with slightly
> custom settings.

That's very encouraging news.

Dave Abrahams
BoostPro Computing

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