portfile question concerning optional deps

[Daniel J. Luke]

On Mar 3, 2011, at 4:52 PM, Marko Käning wrote:
> 
> I want A to be dependent on either B-release or B-devel, exclusively!
> 
> Say, the user has installed B-devel before installing port A: In that case I want to let port A accept B-devel as the default dep.
> If, however, B-release is installed, than that one should be accepted.
> 
> How can I test in the portfile for already installed ports?

Usually this is done with bin/lib/path style dependencies (instead of port)

So, you pick something in B that port A needs to have there (a library, binary, header file) and depend on that.

MacPorts will install the port you choose (which should be B-release by default) if the file isn't found. If the file is there (from either B-release or B-devel), it won't install anything.

You can have a variant which flips which port gets installed (or depends with a port: style dependency instead) if you think that that will make things easier for the end user as well.

For example, if you want to depend on either mysql5 or mysql5-devel, you could use:

path:bin/mysql_config5:mysql5

(which says, look for mysql_config5 in $prefix/bin, if it's not there install the mysql5 port).

This could also be written as:

bin:mysql_config5:mysql5

If you wanted to depend on libsdl.dylib from either libsdl or libsdl-devel, you could use:

lib:libsdl:libsdl

--
Daniel J. Luke                                                                   
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