[Haskell-cafe] Re: cabal install on Windows
duncan.coutts at googlemail.com
Mon Nov 9 11:45:10 EST 2009
On Mon, 2009-11-09 at 16:02 +0000, Michael Fan wrote:
> I figured it out. It appears to be "Colour" package specific.
> The datadir still point to "c:\Program File" even with --user.
> I manually edit the dist/setup-config and get Colour installed.
> After that, other packages seem working fine.
>From the ticket:
On Windows the --datadir is set independently of the --prefix
(at least for libraries). This is actually quite annoying
because it's not discoverable and when you do discover it you've
got to set the datadir along with the prefix on the command line
or in the config file.
The problem is to do with relocatable packages and data files.
Suppose you have a library that has data files. For a
hypothetical example how about some Unicode library that uses
data files of character traits. Now we want to use that library
in a program and we want to have that program be relocatable.
That means that at runtime the library needs to be able to
locate its data files. But the place where the library was
installed is completely independent of where the .exe is being
One way to make this appear to work is for the library data
directory to not really be relocatable, then it looks like we
can relocate the .exe and have it still work. Of course the .exe
is not very re-locatable, in particular it cannot be relocated
to another machine. This is often the use case for relocatable
packages on Windows.
Perhaps another solution would be to place the burden of finding
the data files on the executable, or at least on the process of
preparing the relocatable executable. If we made the process of
generating a relocatable package more explicit we could include
in that process checking for dependent library packages that use
data files. We could then inform the packager and/or copy/link
the necessary data files into a place where the library code
will be able to find them relative to the executable. See #469.
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