This issue came up in Mystcraft

http://mirror1.binarymage.com/mantisbt/view.php?id=182#c1344

 

The basic idea: Back in eternal twilight or eternal night worlds, when the sun in a mystcraft age would never reach the point of uprooting mushrooms, I wanted to plant mushrooms outdoors.

 

XCompWiz has finally closed that issue, with the conclusion that:

1. Given the lack of any simple "eternal night" anymore, there is no simple check,

2. Given the ability to make nights in mystcraft ages as long as 10-12 hours (there is an addon that gives a 24 hour day/night cycle as an option), even in a world with a cycle, you could have 10+ hours of growth, so the presence of a day cycle has no meaning,

3. Given the existing vanilla mechanics and lack of any sort of override,

 

4. Conclusion: permitting this to happen has to be done through forge.

 

So, as a user, wanting something like this, I want to be able to have mushrooms outdoors, in the dark, even if at some point in the future there will be a sun. We now have hoppers and daylight sensors, so a mushroom field could auto-harvest with water and get stored in chests at sunup; this should demonstrate sufficient practicality for the idea.

 

This should already be possible as Mystcraft should just set the skylight values to whatever they need during world gen and it should work fine.

if it doesn't have xcomp look into it and submit a PR.