0005139: add possibilité to customize ocamlbuild options

(0005807)
xclerc (developer)
2011-02-15 14:45

A function named 'add' has been added to 'Ocamlbuild_plugin.Options'.
A command-line option named '-plugin-option' has been added to
ocamlbuild (as it is necessary for the 'pristine' ocamlbuild to ignore
added options).

Here is a 'myocamlbuild.ml' example:
---
open Ocamlbuild_plugin

let () =
  dispatch begin function
    | Before_options ->
        Options.add ("-hello",
                     Arg.String (Printf.printf "Hello %s.\n"),
                     " classical example")
    | _ -> ()
  end
---
and an example of its execution:
  ocamlbuild -plugin-option '-hello' -plugin-option 'world'

(0005808)
daweil (reporter)
2011-02-15 15:32

That works but it is not what I wished! It looks quite heavy to use for the user and it looks redundant with the "--" option of ocamlbuild?
What I wish is really to overwrite any ocamlbuild option, of course, at the own risk, of the plugin developper!
and to call ocamlbuild directly with the option I want :
ocamlbuild -myoption "hello world"

I use ocamlbuild to build project which do not compile any ocaml code. I even want to hide from the user of the plugin I develop that my plugin is able to compile Ocaml code.
That's why I was proposing to change the "spec" list of Ocamlbuild/options.ml into a reference to a list, or to offer a function in the plugin API that overwrite this list.

(0005809)
xclerc (developer)
2011-02-15 15:50
edited on: 2011-02-15 15:50

First, this is not redundant with the "--" option of ocamlbuild that is used to pass
arguments to a produced executable, not to a plugin. Then, the ability to add an
option, but not to bypass / remove any existing one is coherent with the behavior
of both camlp4 and ocamldoc. Finally, my understanding is that what you are
trying to achieve is not to be seen as a plugin task (I reckon this is a matter of taste).

For what you are trying to achieve, I would suggest to use ocamlbuild as
a library (that is "ocamlbuildlib.cm[x]a" in "$PREFIX/lib/ocaml/ocamlbuild").

(0005810)
daweil (reporter)
2011-02-15 16:18

You're right. It's not a plugin that I wish but a "custom" build tool. In that case, what should be my entry points ?

(0005811)
xclerc (developer)
2011-02-15 16:27
edited on: 2011-02-15 16:28

You could take a look at "$ROOT/ocamlbuild/ocamlbuildlib.mllib" that defines
the contents of the library. It contains the following modules:
  - Ocamlbuild_pack;
  - Ocamlbuild_plugin;
  - Ocamlbuild_unix_plugin;
  - Ocamlbuild_executor;
where the three last ones are "top" modules while the first one is a package
whose contents is defined by "$ROOT/ocamlbuild/ocamlbuild_pack.mlpack".
It is too lengthy to list here, but basically you have access to all modules
of the "$ROOT/ocamlbuild/directory" except "Ocamlbuild" that is just the
entry point whose role is to call "Main.main".
In "Ocamlbuild_pack", you will have access to the tags, rules, commands, etc.

(0005812)
daweil (reporter)
2011-02-15 16:35

OK. I understand that I should link with this library, specify my own command line options, customize the main.ml file to parse my options and link it with a copy of ocamlbuild.ml and of course with myocamlbuild.ml file.

(0005813)
xclerc (developer)
2011-02-15 16:41

Well, if your tool is a build tool that need no OCaml support, you can leave
"Main" as it is today, and have your dedicated module that does its own analysis
of the command line. This dedicated module can also receive was used to be
in your "myocamlbuild.ml" file. After, all is a matter of taste and architecture;
the only things you should not do is to call "Main.main", or "Options.init"...

(0005814)
daweil (reporter)
2011-02-15 17:05

OK, I'll try.

(0005815)
ygrek (reporter)
2011-02-16 09:51

Why would one want to add cmdline options to plugin when there is _tags file for that? It looks like duplicate functionality with no benefits..

(0005816)
xclerc (developer)
2011-02-16 10:01

The "_tags" file is essentially a static one describing how to build
while one may want to orthogonally pass options to dynamically
change some parameters (e.g. debug enabled/disabled).

Some simple things may be done through the "-tag" / "-tags" /
"-tag-line" options, but more complex behavior may need the
computation of a plugin. Hence the possibility to add a need
command-line option. Moreover, as pointed out above, this
possibility is coherent with camlp4 and ocamldoc plugins.

(0005817)
xclerc (developer)
2011-02-16 10:03

I mark the issue as "resolved/fixed", but the original reporter
should feel free to add notes or to contact me by mail if the
suggested path does not lead to success.

Issue History
Date Modified	Username	Field	Change
2010-08-31 16:24	daweil	New Issue
2010-11-30 10:49	xclerc	Status	new => assigned
2010-11-30 10:49	xclerc	Assigned To	=> xclerc
2011-02-10 16:16	xclerc	Status	assigned => resolved
2011-02-10 16:16	xclerc	Fixed in Version	=> 3.12.1+dev
2011-02-10 16:16	xclerc	Resolution	open => fixed
2011-02-10 16:16	xclerc	Status	resolved => feedback
2011-02-10 16:16	xclerc	Resolution	fixed => reopened
2011-02-10 16:17	xclerc	Status	feedback => assigned
2011-02-15 14:45	xclerc	Note Added: 0005807
2011-02-15 14:45	xclerc	Status	assigned => resolved
2011-02-15 14:45	xclerc	Resolution	reopened => fixed
2011-02-15 15:32	daweil	Note Added: 0005808
2011-02-15 15:32	daweil	Status	resolved => feedback
2011-02-15 15:32	daweil	Resolution	fixed => reopened
2011-02-15 15:50	xclerc	Note Added: 0005809
2011-02-15 15:50	xclerc	Note Edited: 0005809
2011-02-15 16:18	daweil	Note Added: 0005810
2011-02-15 16:27	xclerc	Note Added: 0005811
2011-02-15 16:28	xclerc	Note Edited: 0005811
2011-02-15 16:35	daweil	Note Added: 0005812
2011-02-15 16:41	xclerc	Note Added: 0005813
2011-02-15 17:05	daweil	Note Added: 0005814
2011-02-16 09:51	ygrek	Note Added: 0005815
2011-02-16 10:01	xclerc	Note Added: 0005816
2011-02-16 10:03	xclerc	Note Added: 0005817
2011-02-16 10:03	xclerc	Status	feedback => resolved
2011-02-16 10:03	xclerc	Resolution	reopened => fixed
2012-02-02 15:17	protz	Category	OCamlbuild => OCamlbuild (the tool)
2012-09-25 20:06	xleroy	Status	resolved => closed

Notes
(0005807) xclerc (developer) 2011-02-15 14:45	A function named 'add' has been added to 'Ocamlbuild_plugin.Options'. A command-line option named '-plugin-option' has been added to ocamlbuild (as it is necessary for the 'pristine' ocamlbuild to ignore added options). Here is a 'myocamlbuild.ml' example: --- open Ocamlbuild_plugin let () = dispatch begin function \| Before_options -> Options.add ("-hello", Arg.String (Printf.printf "Hello %s.\n"), " classical example") \| _ -> () end --- and an example of its execution: ocamlbuild -plugin-option '-hello' -plugin-option 'world'

(0005808) daweil (reporter) 2011-02-15 15:32	That works but it is not what I wished! It looks quite heavy to use for the user and it looks redundant with the "--" option of ocamlbuild? What I wish is really to overwrite any ocamlbuild option, of course, at the own risk, of the plugin developper! and to call ocamlbuild directly with the option I want : ocamlbuild -myoption "hello world" I use ocamlbuild to build project which do not compile any ocaml code. I even want to hide from the user of the plugin I develop that my plugin is able to compile Ocaml code. That's why I was proposing to change the "spec" list of Ocamlbuild/options.ml into a reference to a list, or to offer a function in the plugin API that overwrite this list.

(0005809) xclerc (developer) 2011-02-15 15:50 edited on: 2011-02-15 15:50	First, this is not redundant with the "--" option of ocamlbuild that is used to pass arguments to a produced executable, not to a plugin. Then, the ability to add an option, but not to bypass / remove any existing one is coherent with the behavior of both camlp4 and ocamldoc. Finally, my understanding is that what you are trying to achieve is not to be seen as a plugin task (I reckon this is a matter of taste). For what you are trying to achieve, I would suggest to use ocamlbuild as a library (that is "ocamlbuildlib.cm[x]a" in "$PREFIX/lib/ocaml/ocamlbuild").

(0005810) daweil (reporter) 2011-02-15 16:18	You're right. It's not a plugin that I wish but a "custom" build tool. In that case, what should be my entry points ?

(0005811) xclerc (developer) 2011-02-15 16:27 edited on: 2011-02-15 16:28	You could take a look at "$ROOT/ocamlbuild/ocamlbuildlib.mllib" that defines the contents of the library. It contains the following modules: - Ocamlbuild_pack; - Ocamlbuild_plugin; - Ocamlbuild_unix_plugin; - Ocamlbuild_executor; where the three last ones are "top" modules while the first one is a package whose contents is defined by "$ROOT/ocamlbuild/ocamlbuild_pack.mlpack". It is too lengthy to list here, but basically you have access to all modules of the "$ROOT/ocamlbuild/directory" except "Ocamlbuild" that is just the entry point whose role is to call "Main.main". In "Ocamlbuild_pack", you will have access to the tags, rules, commands, etc.

(0005812) daweil (reporter) 2011-02-15 16:35	OK. I understand that I should link with this library, specify my own command line options, customize the main.ml file to parse my options and link it with a copy of ocamlbuild.ml and of course with myocamlbuild.ml file.

(0005813) xclerc (developer) 2011-02-15 16:41	Well, if your tool is a build tool that need no OCaml support, you can leave "Main" as it is today, and have your dedicated module that does its own analysis of the command line. This dedicated module can also receive was used to be in your "myocamlbuild.ml" file. After, all is a matter of taste and architecture; the only things you should not do is to call "Main.main", or "Options.init"...

(0005814) daweil (reporter) 2011-02-15 17:05	OK, I'll try.

(0005815) ygrek (reporter) 2011-02-16 09:51	Why would one want to add cmdline options to plugin when there is _tags file for that? It looks like duplicate functionality with no benefits..

(0005816) xclerc (developer) 2011-02-16 10:01	The "_tags" file is essentially a static one describing how to build while one may want to orthogonally pass options to dynamically change some parameters (e.g. debug enabled/disabled). Some simple things may be done through the "-tag" / "-tags" / "-tag-line" options, but more complex behavior may need the computation of a plugin. Hence the possibility to add a need command-line option. Moreover, as pointed out above, this possibility is coherent with camlp4 and ocamldoc plugins.

(0005817) xclerc (developer) 2011-02-16 10:03	I mark the issue as "resolved/fixed", but the original reporter should feel free to add notes or to contact me by mail if the suggested path does not lead to success.

Relationships