Other installers putting stuff in /opt/local

[Adam Dershowitz]

> On Jul 30, 2015, at 12:39 PM, Joshua Root <jmr at macports.org> wrote:
> 
> On 2015-7-31 00:37 , Daniel J. Luke wrote:
>> Do we have a doc somewhere where we point other projects to when they’re doing this? (a list of reasons why it’s a bad idea, etc.)?
>> 
>> I just noticed a project doing it and opened a bug in their bug tracker about it - but it would be nice to have that documents some place I could link them to instead of having to explain it if they don’t immediately realize it’s a bad idea.
> 
> We have <https://trac.macports.org/wiki/ProblemHotlist#xmlwf> which
> documents how it affects our users at least.
> 
> - Josh
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I believe that there is also a risk of it breaking existing installed ports, and it would be good to have that explained somewhere as well. 
For example if you install port A and it installs a library.  Then, some other project installs a different version of the same library (different variant for example)  in /opt/local it could break port A.  
I know that I came up against an application that wanted to install this way, and I was able to get in touch with the developers and get it fixed.  But, it did take a bit to explain, and it would have been great to point to a link that explains why this is a bad idea.  They did ultimately change to using a different path for the libraries that they build with Macports.

—Adam