[asdf-devel] :logical-hostname

Wed Mar 31 18:00:08 UTC 2010

On Wed, Mar 31, 2010 at 4:39 PM, james anderson <james.anderson at setf.de>wrote:

> i simply don't understand your requirements. on one hand both with and
> without asdf, but then it is objected, that a mechanism which requires asdf
> does not work without it. please explain.
>

What I do not understand is what YOU do not understand.

In an standalone system there is no ASDF. That is all.

I want to be able to take an ASDF system describing my program and its
dependencies on other libraries and compile it and produce a standalone
executable. That program will not have ASDF inside, it will not have the
notion of a central registry it will have nothing, but it still has to work.

Please understand that the program I am talking about is not a dumped lisp
image that contains everything needed to build the system and even some
extra stuff that was there (database of ASDF systems and other trash). The
programs I produce are just a set of compiled files, one per ASDF system,
linked together with a core library that is the Common Lisp environment ECL
offers.

When the program starts, the linked files are "loaded" one after another, as
if LOAD was used but actually much faster. But I insist again ASDF is not
part of the things that is loaded simply because there is no need.

The only thing that one might need ASDF for is to locate the data associated
to the program, but if we provide logical pathname translations (one host
per library), then a small piece of code can be inserted at the beginning of
the program which locates the data and sets up the appropriate translations.

if the requirement is that exact same exact formulation be used with and
> without asdf, then
> a) the additional system initialization argument is excluded
> b) the second option in my earlier message provides this path.
>

I only find "b" acceptable because I still do not understand how "a" is
going to work without a central registry and a lot of complicated logic that
has to propagate to those distributed binaries.

Having "b", which I recall was one logical host name per system, one may
simply prepend to the compiled set of files a tiny bit of lisp that looks as
follows

(defvar *program-data-location*
#+windows ;; Data and binaries live together
(program-location)
#+unix ;; Data is installed somewhere standard
"/usr/share/program/"
#+osx ;; Assume this is an application bundle
(merge-pathnames "Content/Resources/" (program-location)))

(defun set-host-translation (root extra)
  ...)

(set-host-translation "cl-ppcre" "cl-ppcre/")
(set-host-translation "cl-unicode" cl-unicode/")

With this simple, automatically generated code I can pack the given systems
and let them work anywhere, even though ASDF is not present.

The same or a similar procedure can be used to link many systems into a
single distributable binary fasl + resources, install it in a standard
location that can be found by certain lisps and prepend a simple logic for
finding out its data... Without using ASDF in the file itself.

There is even a third model in which installation paths are known
beforehand. Say that a package maintainer from Debian has the role of
generating binaries for 10 libraries out there and they have complex
inter-dependencies. Libraries can be compiled in the machine of the
maintainer and then installed by ASDF in their standard locations. ASDF can,
in the process, hard-code the pathname translations when installing the
files.

For instance, if we produce binaries for cl-ppcre-1.0.1 and cl-unicode-2.0.1
and the latter depends on the former, and we know that they are going to
live in
/usr/lib/common-lisp/cl-ppcre-1.0.1
/usr/lib/common-lisp/cl-unicode-2.0.1
when "asdf-build" compiles the files and "asdf-installs" them we may get

;; Stripped down version of a system definition
;; which only contains the precompiled files
;; and which can be searched and used by ASDF
/usr/lib/common-lisp/cl-ppcre-1.0.1/cl-ppcre.asd
/usr/lib/common-lisp/cl-unicode-1.0.1/cl-unicode.asd

;; The binaries themselves
/usr/lib/common-lisp/cl-ppcre-1.0.1/cl-ppcre-1.0.1.fas
/usr/lib/common-lisp/cl-ppcre-1.0.1/cl-unicode-1.0.1.fas

;; Proxy binaries that can be loaded using "require"
;; even if ASDF is not present. These files define the logical
;; pathname translations based on hardcoded locations.
/user/lib/common-lisp/cl-ppcre-1.0.1/cl-ppcre.fas
/user/lib/common-lisp/cl-ppcre-1.0.1/cl-unicode.fas

;; Data used by the library
/user/lib/common-lisp/cl-ppcre-1.0.1/cl-unicode.dat

;; Symbolic link to the last version
/usr/lib/common-lisp/cl-ppcre -> cl-ppcre-1.0.1

The FASL without version numbers files can explicitly load the required
versions of the libraries because they know the hardcoded paths of their
files. In doing so they can also set up the appropriate pathname
translations that are used by the other files.

I have listed just two examples with different paradigms on how to build and
distribute software, and which go beyond current use in which the user has
to set up a collection of registries, in your case you even define pathname
translations and have magic to make ASDF understand them, sources are always
present, things are recompiled...

But there are other possibilities. ASDF can be used to produce programs and
libraries that can be distributed, ASDF can itself be used without people
noticing it (see the automatically generated FASL files), it can integrate
with other build processes (via some simple scripts asdf-build, asdf-install
which I may offer to write), we can achieve better system descriptions, and
a lot of things that make people's life easier because they can forget that
they use ASDF at all -- just like when writing C I am free to forget that I
am using "make" at some point.

Juanjo

-- 
Instituto de Física Fundamental, CSIC
c/ Serrano, 113b, Madrid 28006 (Spain)
http://tream.dreamhosters.com
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