Unified DEPENDENCIES concept
 

On Fri, 7 Sep 2012 12:45:59 +0100
Ciaran McCreesh <ciaran.mccreesh@googlemail.com> wrote:

> Since DEPENDENCIES hasn't been written up in a Gentoo-friendly manner,
> and since the Exherbo documentation doesn't seem to suffice to explain
> the idea here, here's some more details on the DEPENDENCIES proposal.
>
> We observe that a typical package will have something like this:
>
> DEPEND="
> cat/first
> cat/second
> cat/third
> cat/fourth
> foo? (
> foo/one
> >=foo/two-2.34[monkeys]
> )
> bar? (
> bar/one
> )
> baz? (
> baz/one
> baz/two
> )
> fnord? (
> fnord/one
> )"
>
> RDEPEND="
> cat/second
> cat/third
> cat/fourth
> cat/fifth
> foo? (
> >=foo/two-2.34[monkeys]
> foo/three
> )
> bar? (
> bar/one
> bar/two
> bar/three
> bar/four
> )"

Now please express that using bash variable references instead of
the overly verbose expansions. Also, real examples are much more useful
than counting and monkeys. This is not mathematics.

> Note how many dependencies that we think of as being "the same" are
> listed in two places, and are not in any way "the same".
>
> Note also how the foo-related things, the bar-related things etc
> cannot be grouped together by their fooness or barness, but are
> rather grouped by their DEPENDness and RDEPENDness.

What is fooness and barness? Because I got lost near the four
non-existent word.

> Right now we've just got three variables. In a not too distant EAPI,
> it will be considerably more than three. We also have duplication;
> with HDEPEND, this will sometimes become triplication.

Sometimes != always. Sometimes HDEPEND will actually simplify
the current state. By moving a few things from DEPEND to HDEPEND, we
may be actually able to remove COMMON_DEPEND. Sometimes.

> Here's the important bit, which I shall prefix with some stars:
>
> *** The point of DEPENDENCIES is not to replace n variables with one
> *** variable.

Yes, it is.

> *** The point of DEPENDENCIES is not to provide syntactic sugar over a
> *** group of n variables.

Yes, it is.

> *** The point of DEPENDENCIES is to allow a package's dependencies,
> *** which can be very complicated, to be expressed accurately and
> *** simply, in a way friendly to how developers deal with dependencies
> *** in practice.

Didn't we already prove that the syntactic sugar DEPENDENCIES allows
can make the dependency specifications very unclear and not anywhere
close to simple?

> So here's what DEPENDENCIES solves:
>
> Firstly, it allows developers to group together foo-related
> dependencies and bar-related dependencies by their fooness and
> barness, not by their role.
>
> Secondly, it reduces error-prone duplication.

No, it doesn't. It just provides an alternate solution over how we do
that now. Does variable substitution ring a bell?

> Thirdly, it avoids some fairly obtuse names (BADEPEND? LDEPEND?) in
> favour of something a tad more readable.

That is a side effect. DEPENDENCIES doesn't disallow us from choosing
to use labels like 'd:', 'r:'. Similarly, bash variables don't anyhow
stand in the way of using more verbose names.

> Here's the other important bit, with more stars:
>
> *** It does it by replacing the concept of "a package has build
> *** dependencies, run dependencies, etc" with "a package has
> *** dependencies, and each dependency is applicable at one or more of
> *** build time, run tme, etc".

Really?

I think it actually gives concept of 'a package has a few random groups
of dependencies, where each group is applicable at one or more of build
time, run time, etc and consists of one or more dependencies or groups
of dependencies, where each group is applicable at one or more of build
time, run time, etc (which may or may not be the same as parent group)
and consists of one or more dependencies or groups of dependencies,
where each group is applicable at one or more of build time, run time,
etc (which may or may not be the same as parent group) and consists of
one or more dependencies or groups of dependencies, where each group is
applicable at one or more of build time, run time, etc (which may or
may not be the same as parent group) and consists of one or more
dependencies or groups of dependencies, where each group is applicable
at one or more of build time, run time, etc (which may or may not be
the same as parent group) and consists of one or more dependencies or
groups of dependencies, where each group is applicable at one or more
of build time, run time, etc (which may or may not be the same as
parent group) and consists ...'

> We could just mark each dependency individually by when it's
> applicable. But that turns out to be quite verbose, since packages
> have fairly long lists of dependencies of the same kind. So here's a
> much more concise syntax:
>
> DEPENDENCIES="
> build:
> cat/first
> build+run:
> cat/second
> cat/third
> cat/fourth
> run:
> cat/fifth
>
> foo? (
> build:
> foo/one
> build+run:
> >=foo/two-2.34[monkeys]
> run:
> foo/three
> )
>
> bar? (
> build+run:
> bar/one
> run:
> bar/two
> bar/three
> bar/four
> )
>
> build:
> baz? (
> baz/one
> baz/two
> )
>
> fnord? (
> fnord/one
> )"
>
> Here are the rules for working out which labels apply to a given spec:
>
> We have a "labels stack" when parsing. Initially, the value
> "build+run" is on the top. Whenever we encounter a block ("( )",
> "use? ( )" etc), we duplicate the top value of the stack, and when we
> leave the block we pop the value off. Whenever we encounter labels,
> we replace the top value on the stack with those labels. Whenever we
> encounter a spec, its associated labels are those on the top of the
> stack.

These are the rules for a machine. People don't actually read
dependencies sequentially. Provide a good algorithm which works from
any position.

> To avoid weirdness, so long as we're inside a || block, use of labels
> is forbidden. Note that this is a reflection of the current ambiguity
> as to what DEPEND="|| ( a b )" RDEPEND="|| ( a b )" means (can you
> build against a, and run against b?), and if we're wanting to tidy
> that up, that should be an independent proposal.

Yes, that's something you could work on instead of throwing a lot of
work on us just to reinvent the wheel your way because you believe that
your bicycle is much better when it has square wheels.

> These rules are mostly for flexibility: if developers sometimes prefer
> to group things by role rather than by fooness, then that's possible
> too.
>
> The rules for eclass merging need changing too, to add a ( ) around
> values rather than merely appending. This is a technicality, and isn't
> developer visible.

The algorithm you presented above was technicality as well.

So, now that your forked the thread shall we repeat all
the disadvantages which you love to forgot to mention?

--
Best regards,
Michał Górny

Unified DEPENDENCIES concept
 

On Fri, 7 Sep 2012 14:29:41 +0200
Michał Górny <mgorny@gentoo.org> wrote:
> > Here's the important bit, which I shall prefix with some stars:
> >
> > *** The point of DEPENDENCIES is not to replace n variables with one
> > *** variable.
>
> Yes, it is.

You've clearly either completely missed the point of all of this,
despite it being pointed out to you, or are just trying to cause
trouble. Whilst you may be thinking of a DEPENDENCIES proposal that is
about replacing n variables with one variable (and I've never seen such
a proposal being made), what we're discussing here is not that. Kindly
stay out of this discussion until you understand what it is we're
discussing.

> These are the rules for a machine. People don't actually read
> dependencies sequentially. Provide a good algorithm which works from
> any position.

Read backwards from the current position until you find a label. It's
the same algorithm you use to find out what the current section is when
you're reading an article.

> The algorithm you presented above was technicality as well.

Agreed, but it was explicitly requested by Brian, so I provided it.

> So, now that your forked the thread

...as requested by Brian...

> shall we repeat all the disadvantages which you love to forgot to
> mention?

No, please stay out of this until you understand the original proposal,
and in particular the parts marked with ***. So long as you don't
understand what we're discussing, I'm afraid any contributions you make
will simply be shouting and waving.

--
Ciaran McCreesh

Unified DEPENDENCIES concept
 

On Fri, 7 Sep 2012 13:36:05 +0100
Ciaran McCreesh <ciaran.mccreesh@googlemail.com> wrote:

> > These are the rules for a machine. People don't actually read
> > dependencies sequentially. Provide a good algorithm which works from
> > any position.
>
> Read backwards from the current position until you find a label. It's
> the same algorithm you use to find out what the current section is
> when you're reading an article.

No, it doesn't work that way.

See:

foo? (
label:
dev-foo/bar
)
dev-bar/foo <-

Reading backwards, I find 'label'.

> > shall we repeat all the disadvantages which you love to forgot to
> > mention?
>
> No, please stay out of this until you understand the original
> proposal, and in particular the parts marked with ***. So long as you
> don't understand what we're discussing, I'm afraid any contributions
> you make will simply be shouting and waving.

What have parts marked with '***' to do with the disadvantages we have
already proved and which you didn't even bother answering?

--
Best regards,
Michał Górny

Unified DEPENDENCIES concept
 

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On 07/09/12 07:45 AM, Ciaran McCreesh wrote:
> [ Snip! ] Note also how the foo-related things, the bar-related
> things etc cannot be grouped together by their fooness or barness,
> but are rather grouped by their DEPENDness and RDEPENDness.
>
> [ Snip! ]
>
> So here's what DEPENDENCIES solves:
>
> Firstly, it allows developers to group together foo-related
> dependencies and bar-related dependencies by their fooness and
> barness, not by their role. [ Snip! ] *** It does it by replacing
> the concept of "a package has build *** dependencies, run
> dependencies, etc" with "a package has *** dependencies, and each
> dependency is applicable at one or more of *** build time, run tme,
> etc".

And this is the specific point that I don't like about DEPENDENCIES
versus *DEPEND. As a developer, I personally find it much more
straight-forward to fill in the deps needed for each role, rather than
specifying the role(s) that each dep will play a part in.

Although I realize that technically I could still do that (have the
dep list be role-centric rather than dep-centric), given that the
point of this change is (as stated above) to organize deps the other
way, I can't really get behind the idea.


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Unified DEPENDENCIES concept
 

On Fri, 7 Sep 2012 16:23:16 +0200
Michał Górny <mgorny@gentoo.org> wrote:
> On Fri, 7 Sep 2012 13:36:05 +0100
> Ciaran McCreesh <ciaran.mccreesh@googlemail.com> wrote:
> > > These are the rules for a machine. People don't actually read
> > > dependencies sequentially. Provide a good algorithm which works
> > > from any position.
> >
> > Read backwards from the current position until you find a label.
> > It's the same algorithm you use to find out what the current
> > section is when you're reading an article.
>
> No, it doesn't work that way.
>
> See:
>
> foo? (
> label:
> dev-foo/bar
> )
> dev-bar/foo <-
>
> Reading backwards, I find 'label'.

...skipping subblocks. Although the case you've given is unlikely to
be used in practice, since experience shows that given this feature,
developers use it in an easily understood manner.

> > > shall we repeat all the disadvantages which you love to forgot to
> > > mention?
> >
> > No, please stay out of this until you understand the original
> > proposal, and in particular the parts marked with ***. So long as
> > you don't understand what we're discussing, I'm afraid any
> > contributions you make will simply be shouting and waving.
>
> What have parts marked with '***' to do with the disadvantages we have
> already proved and which you didn't even bother answering?

The problem is that you're arguing against a proposal that doesn't
exist except in your head. If you'd like to read and understand the
proposal being made, which starts with understanding the bits marked
clearly with stars, and then once you've understood it, rethink and
present any issues you find with that proposal then we might have
something to discuss.

--
Ciaran McCreesh

Unified DEPENDENCIES concept
 

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On Fri, 07 Sep 2012 10:50:40 -0400
Ian Stakenvicius <axs@gentoo.org> wrote:
> On 07/09/12 07:45 AM, Ciaran McCreesh wrote:
> > [ Snip! ] Note also how the foo-related things, the bar-related
> > things etc cannot be grouped together by their fooness or barness,
> > but are rather grouped by their DEPENDness and RDEPENDness.
> >
> > [ Snip! ]
> >
> > So here's what DEPENDENCIES solves:
> >
> > Firstly, it allows developers to group together foo-related
> > dependencies and bar-related dependencies by their fooness and
> > barness, not by their role. [ Snip! ] *** It does it by replacing
> > the concept of "a package has build *** dependencies, run
> > dependencies, etc" with "a package has *** dependencies, and each
> > dependency is applicable at one or more of *** build time, run tme,
> > etc".
>
> And this is the specific point that I don't like about DEPENDENCIES
> versus *DEPEND. As a developer, I personally find it much more
> straight-forward to fill in the deps needed for each role, rather than
> specifying the role(s) that each dep will play a part in.

Have you tried doing both? You may find you're just arguing from
familiarity, and that after having worked the other way for a few
packages, that the advantages become clearer.

The wide-spread use of hacks like COMMON_DEPEND are a pretty strong
indication that people *do* think in something closer to a
DEPENDENCIES-like fashion. In particular, I find it hard to believe
that you think "ok, so I've got a build dependency upon
>=cat/pkg-2.3[foo]" and then independently work out "ok, I've got a run
>dependency upon >=cat/pkg-2.3[foo]".

- --
Ciaran McCreesh
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Unified DEPENDENCIES concept
 

On Fri, 7 Sep 2012 15:53:50 +0100
Ciaran McCreesh <ciaran.mccreesh@googlemail.com> wrote:

> On Fri, 7 Sep 2012 16:23:16 +0200
> Michał Górny <mgorny@gentoo.org> wrote:
> > On Fri, 7 Sep 2012 13:36:05 +0100
> > Ciaran McCreesh <ciaran.mccreesh@googlemail.com> wrote:
> > > > These are the rules for a machine. People don't actually read
> > > > dependencies sequentially. Provide a good algorithm which works
> > > > from any position.
> > >
> > > Read backwards from the current position until you find a label.
> > > It's the same algorithm you use to find out what the current
> > > section is when you're reading an article.
> >
> > No, it doesn't work that way.
> >
> > See:
> >
> > foo? (
> > label:
> > dev-foo/bar
> > )
> > dev-bar/foo <-
> >
> > Reading backwards, I find 'label'.
>
> ...skipping subblocks. Although the case you've given is unlikely to
> be used in practice, since experience shows that given this feature,
> developers use it in an easily understood manner.
>
> > > > shall we repeat all the disadvantages which you love to forgot
> > > > to mention?
> > >
> > > No, please stay out of this until you understand the original
> > > proposal, and in particular the parts marked with ***. So long as
> > > you don't understand what we're discussing, I'm afraid any
> > > contributions you make will simply be shouting and waving.
> >
> > What have parts marked with '***' to do with the disadvantages we
> > have already proved and which you didn't even bother answering?
>
> The problem is that you're arguing against a proposal that doesn't
> exist except in your head. If you'd like to read and understand the
> proposal being made, which starts with understanding the bits marked
> clearly with stars, and then once you've understood it, rethink and
> present any issues you find with that proposal then we might have
> something to discuss.

Renaming and/or reordering something doesn't change its implications.
It's just 'main disadvantage' vs 'side disadvantage'.

--
Best regards,
Michał Górny

Unified DEPENDENCIES concept
 

On Fri, 7 Sep 2012 17:02:57 +0200
Michał Górny <mgorny@gentoo.org> wrote:
> > The problem is that you're arguing against a proposal that doesn't
> > exist except in your head. If you'd like to read and understand the
> > proposal being made, which starts with understanding the bits marked
> > clearly with stars, and then once you've understood it, rethink and
> > present any issues you find with that proposal then we might have
> > something to discuss.
>
> Renaming and/or reordering something doesn't change its implications.
> It's just 'main disadvantage' vs 'side disadvantage'.

Well no. You've been arguing against some mysterious proposal that
doesn't exist that you think is about replacing lots of variables with
one variable. That's not what DEPENDENCIES is, and now that you've got
a proper write-up, you can try reading it, understanding it and then
seeing if you have any objections to what's actually being proposed.

--
Ciaran McCreesh

Unified DEPENDENCIES concept
 

On Fri, 7 Sep 2012 16:07:54 +0100
Ciaran McCreesh <ciaran.mccreesh@googlemail.com> wrote:

> On Fri, 7 Sep 2012 17:02:57 +0200
> Michał Górny <mgorny@gentoo.org> wrote:
> > > The problem is that you're arguing against a proposal that doesn't
> > > exist except in your head. If you'd like to read and understand
> > > the proposal being made, which starts with understanding the bits
> > > marked clearly with stars, and then once you've understood it,
> > > rethink and present any issues you find with that proposal then
> > > we might have something to discuss.
> >
> > Renaming and/or reordering something doesn't change its
> > implications. It's just 'main disadvantage' vs 'side disadvantage'.
>
> Well no. You've been arguing against some mysterious proposal that
> doesn't exist that you think is about replacing lots of variables with
> one variable. That's not what DEPENDENCIES is, and now that you've got
> a proper write-up, you can try reading it, understanding it and then
> seeing if you have any objections to what's actually being proposed.

Ah, I forgot how the goals change *everything*. Because it's good to
kill hundreds of people for the good reasons.

--
Best regards,
Michał Górny

Unified DEPENDENCIES concept
 

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(Just for the record, I don't care about the merits or demerits of
*DEPEND or DEPENDENCIES.)

> Ah, I forgot how the goals change *everything*. Because it's good
> to kill hundreds of people for the good reasons.

You might want to take a short break to consider if you're taking
things a bit too seriously or are at least phrasing them a little
strongly here.
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