On 18.10.2013 15:58, janI wrote:
On 18 October 2013 15:00, Andre Fischer <awf....@gmail.com> wrote:
On 18.10.2013 14:02, janI wrote:
sd
On 18 October 2013 13:36, Andre Fischer <awf....@gmail.com> wrote:
On 18.10.2013 11:32, janI wrote:
Hi.
due to the discussion in thread "Mentor a new build system", I have
made a
proposal for a central Makefile located in main.
Hi Jan,
it is great that you are going to improve this part of the build system.
But I think that we need more details about how the proposed build
system
works. Without them I can not really evaluate the proposal.
First of all, I agree with juergens remarks that this should be
discussed
before implemented, hence the wiki page.
Secondly this has nothing directly to do with the proposed build system,
its a simple replacement of build.pl in the current system.
Yes, that is how I understood it. I just did not know how to call the
build.pl replacement.
I know that build.pl works, but having a Makefile in main, would make us
one step closer on being compatible with the distros. To me this job is a
simple cleanup, not something we deadly need, but nice to have.
Some remarks regarding the missing options:
--from <module>
This is one of the more important options and one that I use
frequently
(also in the form --all:<module>).
Note that if you are in <moduleA> and call 'make --from <moduleB>'
then
all modules are built
a) which <moduleA> depends on
b) but not those that <moduleB> depends on
c) Both <moduleA> and <moduleB> are built.
I have changed the documentation.
I use the --all:<module> myself very often, and have changed the
documentation, because it is of course supported.
The difference is that you do the call in main, but that is a minor detail
that can be easily corrected (have <module>/Makefile calling
main/Makefile.
I have also changed documentation on --html due to juergens comments.
I am not sure that we understand --from and --since in the same way so I
will try to explain what I think they do.
Let's imagine that we have a simple project with modules A, B, C, D and E.
where B depends on A, C on B, D on C, and E on D.
A ' make all' would mean 'make E'. The dependencies would then lead to
building modules A, B, C, D, E in this order.
If I am in E and call 'make --from C' then only C, D, and E should be
built. A 'make --since C' would only build D and E.
If I am in D and call 'make --from B' then modules B, C, and D are built.
Call 'make --since B' to build only C and D.
Note that 'make --from' accepts more than one module name (while 'make
--all:<module>' does not).
Note also that in the above case (stand in D, call 'make --from B') module
A is not built, regardless of whether there are changes in A or not.
Whereas a simple call to make (still standing in D) would build all
modules that D depends on, directly or indirectly. Thus the options
'--from' and '--since' exist to actively exclude modules from being built.
The whole thing becomes a little bit more complicated with multiple
options to '--from' (I never use '--since' and also don't know a valid use
case so I will ignore it for now) and more complex dependencies then in the
simple example above. Let's say that if we stand in instsetoo_native and
call 'make --from svx sfx2'. Note that svx depends on sfx2. This would
build svx, sfx2 and all modules that depend (directly or indirectly) on svx
OR sfx2.
got it, now I just have one problem, why would you not build the dependent
modules, if they needed to be built, thats a scenario I dont understand.
With a central makefile, <module>/makefile will not be called so we do not
waste cpu cycles.
With the .done files, we know when a module was last built and all modules
that depend it should be rebuilt which the rule
<module>.done : <module_depend>.done
will ensure, so If we have A -> B -> C -> D
I go in B, and call make, then when I go in D and make, B,C,D will be made.
If we have A -> B -> D C -> D
and do the same then only D will be made.
So --from is not really saving anything ?
a) In your example you first go into B then, in a second step, into D.
The '--from' option lets you do the same (well, not really the same, but
see below) just from D.
b) You go first to B and call make. This makes A, if necessary, then
B. The making of A is exactly the thing that you want to prevent with
the '--from' option. Go into D and call 'make --from B'. A is not built.
c) After the discussion with you I am not sure if we still need --from
because the two reasons I know for its existence my not be relevant with
the new approach.
c1) With the '--from' option you can tweak the dependency rules at
runtime (a bit). This allows you to exclude projects from being built
when you know that that is not necessary. But from experience I know
that can lead to very subtle errors. Letting the system determine what
to built is usually more reliable.
c2) With build.pl a 'build --all' still builds every module on which the
one you are standing in depends on. When those modules have been built
previously, then no compilation takes place. But calling dmake for a
couple of directories for close to 200 modules (when you stand in
instsetoo_native) takes a lot of time (several minutes on Windows), even
when no file has to be compiled. This wasteful way of doing nothing can
be prevented with the --from option.
However, with the new approach and its .done flag files you can
determine which modules need to be built much faster. You don't have to
call dmake on directories that where already built. Hm, but this again,
does only work if your .done files have dependencies on all relevant
source files. That is something that is missing at least from my script.
So, reasons for the existence of '--from' are a result of old/slow
computers, slow files systems (still valid on Windows), missing global
dependencies (which we now have for gbuild) and impatient developers.
While this is easy to do with eg Perl I am not sure how to handle this
with just a Makefile. The straightforward approach with handling
<module>.done files does not work. And that is one of the reasons why I
don't think that (GNU) makefiles are a good solution for any problem. Most
of us are used to program object oriented/imperative. Makefiles require a
declarative approach. Maybe the use of Perl is not such a bad idea. Maybe
it would be better to reimplement build.pl with a lot fewer options and
with better readable code.
I agree that makefiles are nowhere near a good solution to many of these
problems, but its like windows, I dont like it, but everybody uses it.
We could easily write a new build.pl, that also took care of the local
makefiles, but our build system would not be in the mainstream, and e.g.
the distros would not like to integrate AOO.
I have over the last years followed research in building systems, and there
are (sadly enough) nobody that tries a real object oriented aproach. Also
if you look at packages like visual studio, QT, eclipse they all use the
principle of makefiles with declarative approach.
So my simple question is, do we want to approach the main road (makefiles
for unix, visual studio for windows/mac) or do we want to have better but
non standard system.
Good analysis. Maybe I should answer with Faust: "Zwei Seelen wohnen,
ach! in meiner Brust" (two souls alas! are dwelling in my breast). The
pragmatist says to use the make. It is good enough for others, it is
good enough for use.
On the other hand, when I start a new project I usually start with the
question of what are the best tools for the problem at hand. And make
does not seem to be the first or the best answer. Look at our dmake or
gbuild system. Both don't use make in a standard way. gmake even
defines its own language, object oriented and imperative, on top of the
GNU make macros. That is, for me, an act of desperation.
I have made experiments with an alternative approach, a domain specific
language somewhat similar to Java. I personally like this approach because
a) it uses the paradigm that I already use when writing C++ code. That
means that I can apply my existing knowledge to the build process and
that I don't have to remember all the tricks and pitfalls of makefiles.
b) as expected it was much easier to handle file dependencies and
parallel processing of build jobs in Java than adding object orientation
and imperative control flow to makefiles.
If I had the time and if I would be the one working on it then I would
prefer an non-Makefile approach. But maybe I am just suffering too much
from one of the 'three great virtues of a programmer': hubris.
You are the one who leads the build project changes, so you have to
decide which approach to use. I am not trying to make your life harder
(than necessary), I am only trying to point out some of the pitfalls
that I have encountered in the past. And to prevent you from removing
features that I use :-)
rgds
jan I.
Ps. its always refreshing to discuss with you, you often have an
alternative approach, which is not just a dream but doable.
Thanks. That makes two of us.
Have a nice weekend,
Andre
-Andre
--prepare
Also one option that is important for our every day work. Use case:
You make changes in <module> and are not sure if these changes are
compatible/incompatible. To be on the safe side you discard the output
of
all depending modules. To save time you keep the output of all other
modules.
Often used together with '--from' like 'make --prepare --from svx' to
prepare a build after making changes in svx.
Documentation changed, funny thing is that svx does not clear correctly
on
my ubuntu build.
--since <module>
A variant of '--from'. The only difference is that <module> itself
is
not built.
If your proposed approach is similar to what my script produces then
it
is not too difficult to support --from/--since. I made some experiments
in
this direction but was to lazy to finish them.
My approach is very similar, but I failed to see how --since is
supported.
And question is if its real important.
--job
--pre_job
--post_job
These are sometimes handy to run a non-standard command for all
modules.
I have added them, they are by the way a good example why we need a
discussion I have never used them.
However maybe the real discussion is "do we want to replace build and have
a main/Makefile instead?"
- I have not used the rest of the unsupported options and would not miss
them. Others may have other sets of options that are important to them.
Some general remarks:
- Why keep one makefile per module? Why not put all the inter-module
dependencies into one file (like my script does)?
Ups, I did not explain that correctly, I propose 1 Makefile
"main/Makefile"
with all inter-module and 1 Makefile "<module>/Makefile" that today just
will call the old makefiles as described in prj/build.lst
- Why not use the oportunity to move (a part of) the build environment out
of the way to, say, build/ ?
You have guessed my next step.
- How are dependencies between modules handled (just the manual
dependencies from prj/build.lst or also the file dependencies introduced
by
gmake).
See doc. on --from. Its done with <module>.done files
- How is the output of the individual calls to dmake or GNU make
handled/made accessible. Ie. if there is a build error, how can I look
up
the corresponding build output?
see doc. script make_log
- Are the gmake makefiles included (run in the same process) or is GNU
make started for them it its own process?
For a start they would be called (own process), but its something where
I
have no strong opinions.
Please (just to be sure), this proposal has nothing to do with the
students
work, its simply because I saw a positive discussion on removing build.pl
,
and spent a couple of hours looking at it. If there is a preference not to
remove build.pl I will simply forget it.
rgds
jan I.
Regards,
Andre
It has been roughly tested it, thanks to a clever utility from andre.
As discussed build.pl contains a lot of options, which need to be
considered in a makefile.
My suggestion is on
http://wiki.openoffice.org/****wiki/Build_System_Analysis:**<http://wiki.openoffice.org/**wiki/Build_System_Analysis:**>
build.pl_versus_makefile<http:**//wiki.openoffice.org/wiki/**
Build_System_Analysis:build.**pl_versus_makefile<http://wiki.openoffice.org/wiki/Build_System_Analysis:build.pl_versus_makefile>
Please feel free to edit/comment on the page. I have reduced to options
a
lot, and some of them might be in use.
thanks in advance for your comments.
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