CoCoA » CoCoA-5

Discovering that BOOST seems to offer a ready-made solution, and that access is old-style C-library.

The purpose of the original code is unclear -- indeed it looks implausible/wrong.

  if (defaultPackageDir && access(packageDir.c_str(), F_OK))
    packageDir = ".";

To answer the question "why...?" in the last update: the fn access returns 0 if the file exists, and -1 if it does not (the opposite of what I expected).

I have replaced the relevant line of code with calls to fns from the BOOST sublibrary filesystem. This makes the source far more readable, and presumably portable too -- at the cost of requiring a (more) complete installation of BOOST on the computer you want to compile on.

JAA does not see the point of permitting CoCoA-5 to be run without its standard libraries. The same end effect could easily be achieved by creating an empty directory somewhere, and then starting CoCoA with the --package-dir option saying to look in that empty directory for packages.

It seems better to issue an error if one has a "broken" CoCoA installation which is missing the standard package directory -- this is a design issue, and must be discussed with Anna.

Anna could you reply to my question in post 5?

I think it should be an error to start CoCoA without the packages. JAA thinks that if you really want to do this, you must use a command line flag (e.g. --without-packages).

Can you think of a scenario when it might actually be useful to run CoCoA without the packages?

Note to JAA: regardless of Anna's answer, the code must always check for the presence of the packages (i.e. it will always be dependent on the BOOST fns I have used).

John Abbott wrote:

Waiting for Anna's return to discuss the correctness/usefulness of allowing CoCoA-5 to run if there's a problem with the default package directory.

I agree it is very likely an error that one should start CoCoA-5 without the packages, but CoCoA-5 can do a lot of things (eventually, in our dreams, everything) without the packages.
So I think it should be allowed to use CoCoA without the packages, maybe with a BIG WARNING banner.

Anna's point about almost everything (eventually) being built-in is valid; I was forgetting that. Also my "note" in post 7 points out that there is no source code simplification in giving an error rather than a warning.

So, let's give a highly visible warning (together with an indication of where CoCoA expected to find its packages).

JAA reiterates that he thinks the use of the BOOST fns is the neatest portable solution (too bad about needing a more complete BOOST installation).