Re: Ada package registry?

[Mart van de Wege <mvdwege@gmail.com>]

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> On 2016-01-30 23:14, Tero Koskinen wrote:
>
>> Usually the repositories are maintained in "wiki"-style and anyone can
>> update the package details (within certain limits). This causes some
>> security concerns/implications, but in general there is not that much
>> abuse and the repositories work well enough.
>>
>> The package repository management tool is used like this:
>>
>>   $ language_package_mananager install X
>>   Downloading dependencies for 'X', please wait a while...
>>   Downloading X...
>>   Package 'X' installed!
>>   $
>
> Yes, the problem is to have it working.
>
>> Once the package (a library usually) is installed (to your home
>> directory), you can link it to your program and simply use it.
>
> No, that the point. It cannot be installed in your home directory. It
> must be in the directories mandated by the target system
> policy. E.g. for Debian Linux:
>
> https://people.debian.org/~lbrenta/debian-ada-policy.html#Files-provided-by-the-_002ddev-package
>
Nope. I am most familiar with Perl, so I shall use that as an example
throughout.

Installing CPAN packages through the CPAN manager requires you to either
adjust the PERLLIB environment variable, or to add a 'use lib' pragma to
your code.

Managing ADA_INCLUDE_PATH in an Ada equivalent would not be much
different.

Plus, as in CPAN, if the libraries are laid out along a standard policy,
it would be easy to provide tools to build system-local packages, like
dh_make_perl does for Perl on Debian.

>> People using other programming languages have managed to create
>> these package repositories, so it is a shame if Ada programmers
>> cannot manage to do the same.
>
> I guess these are scripting languages and pure packages having no
> access to the system environment otherwise than through the language
> run-time. There is no problem to do same for GNAT. That is not Ada
> case. Most Ada packages do access platform-specific non-Ada
> libraries. Pure Ada packages face no problem, if gpr file is provided.
>
This is not unique to Ada. Perl also has packages that require non-Perl
libraries to be available, like XML::LibXML and Text::CSV::XS. The first
has a dependency on libxml2, the second brings its own C code that must
be compiled and then accessed from the Perl module.

In both cases a hard build dependency on a working gcc environment
exists; it is the end-user's responsibility to make sure it does exist
and that the proper header files for the dependencies are installed.

Really, this is not a new issue. It is solvable, if you let go of the
NIH mentality.

Mart

-- 
"We will need a longer wall when the revolution comes."
    --- AJS, quoting an uncertain source.