Subject: Re: [boost] [Modularization] A new approach to header modularization
From: Christopher Jefferson (chris_at_[hidden])
Date: 2009-05-29 03:26:51
On 29 May 2009, at 07:49, Vladimir Prus wrote:
> joaquin_at_[hidden] wrote:
>> Emil Dotchevski escribió:
>>> On Thu, May 28, 2009 at 11:15 PM, Joaquin M Lopez Munoz <joaquin_at_[hidden]
>>> > wrote:
>>>> Emil Dotchevski <emildotchevski <at> gmail.com> writes:
>>>>> On Thu, May 28, 2009 at 10:50 PM, <joaquin <at> tid.es> wrote:
>>>>>> Why there's pressure from users to keep Boost libs header-only?
>>>>>> Boost is
>>>>>> for the users, so their reasons should be given proper weight.
>>>>> One can not create good design (in general, not just in
>>>>> software) by
>>>>> asking the users what would they like.
>>>> I'd rather not go into discussing such far-reaching issues
>>>> as design theory, but you haven't asked my question:
>>>> What are the particular reasons why users demand header-only
>>> Probably different users have different reasons. One reason might be
>>> that it makes Boost easier to install initially. What's your point?
>> My point is that if there's pressure from users to have header-only
>> libs (as
>> you and also I recognize) I think the least we can do is try to
>> understand and
>> analyze these reasons to see their merit. If pressure were the other
>> way around (i.e. users demanding that code be moved out of .hpps as
>> much as possible) we wouldn't be having this sort of discussions.
> It it my understanding (based on actually supporting users on IRC and
> mailing lists for years), that the users who are mostly concerned
> linking are either:
> 1. Users who just crossed the chasm between the two popular platforms,
> in either direction.
> 2. Users who don't understand the difference between headers and
> in general, and don't know how to use their IDE.
> 3. Users who don't know C++.
> Users in (1) group will adapt quickly. Users in groups (2) and (3)
> probably won't be able to use Boost effectively until they do some
> other learning.
I have consistently found that boost seems to cause more problems for
developers than all the other libraries I use put together, in terms
of building and linking.
I work with a large number of developers on users on many different
OSes and processors, so we distribute as source. Some users use
packaged copies of boost distributed with their system, other compile
>> As a user, I can describe *my* reasons to favor header-only libs:
>> 1. The whole bjam-driven building process is nontrivial and time and
>> space consuming.
> In 1.39, it is two commands in 1.39, on popular platforms. And
> are fast these days.
Is if ./configure && make?
>> 3. Bulding libs selectively is not as easy as it might seem, due to
>> fact that interlib dependencies might force you to build libB when
>> libA, and you don't know in advance.
> And you should not care. If you add --with-filesystem, then the system
> library will be built automatically.
Most users aren't going to go around looking for options, they will
assume the default ones do the right thing.
I do love boost, which is why I've fought to make sure we continue
using it, but compared to other libraries it is often a pain. Much of
the pain goes away for header-only libraries.
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