CoCoA » CoCoA-5

ouch!
it should never happen, really.
But it is bad. I'll fixi it.

I see that this give error with no crash (loading extra manuals). This was what worried me most.

ReloadMan(["aksjf"]);

If CoCoAHelp.xml is missing then the installation is broken (or there is a wrong path).
Crashing/aborting may be a reasonable action in these circumstances (who know what else is broken).
There should nevertheless be a helpful message printed on std::cerr before crashing.

I have modified the error message slightly. Now it gives:

/**/ ?abc
--> ERROR: CoCoA-5 manual missing (or not readable); it should be in /home/jabbott/Work/CoCoALib-0.99/src/CoCoA-5/packages/../CoCoAManual/CoCoAHelp.xml
--> [CoCoALib] OnlineHelp::OpenXMLManual()
--> ?abc
--> ^^^^

I think this may be more comprehensible. Anna, what do you think?

It would be nice (& cleaner) if we could get rid of packages/../.
I think this should be possible.

There is a stackoverflow thread about getting dirname: https://stackoverflow.com/questions/3071665/getting-a-directory-name-from-a-filename

Apparently in C++17 one do something like the following:

#include <iostream>
#include <filesystem>
namespace fs = std::filesystem;
int main()
{
    for(fs::path p : {"/var/tmp/example.txt", "/", "/var/tmp/."})
        std::cout << "The parent path of " << p
                  << " is " << p.parent_path() << '\n';
}

boost::filesystem::path p("C:\\folder\\foo.txt");
boost::filesystem::path dir = p.parent_path();

We probably need to change the fn CoCoAManFileName (around line 950 in OnlineHelp.C).
The return type should be a "path" (initially boost::filesystem::path)

const boost::filesystem::path& CoCoAManFileName()
{
  static const boost::filesystem::path UniqueCopy(boost::filesystem::path(packageDir).parent_path() / "CoCoAManual/CoCoAHelp.xml");
  return UniqueCopy;
}

NOTE should we also change the (global) variable packageDir so that it has type boost::filesystem::path? Probably!