[Rivet] RivetGun news: dynamic rivetgun reinstated, run params from file...

[Andy Buckley]

Lars Sonnenschein wrote:
> 
>> How does GENSER handle the different versions of the C++ generators,
>> where the generator subcomponents themselves are dynamically loaded
>> libraries?
> 
> Herwig++ has only one version. 

Actually, it already has two but the first isn't recommended and doesn't
do hadron collisions, so probably isn't and never will be in GENSER. In
future there will undoubtedly be more versions, which is what I'm really
concerned about - we'll want to compare them to each other when they appear.

> Sherpa has two versions. Both are in completely separated subdirectories
> with their respectively own complete sets of shared libraries. 

Again, there will be more versions as time passes, and the fact that
there are different directories with similar but different shared
libraries means that we have to be very careful about how RivetGun
handles the library load paths. Otherwise we could end up concluding
that versions A and B have e.g. indistinguishable parton showers when
what really happened was that both versions accidentally loaded the same
shower library because of a path issue!

Andy