JuliaLang/julia — pull request #6884 by vtjnash (2014-05-19 05:43:36+00:00)
Title: adds conditional modules (#6195)

conditional modules (described in julep #6195) are executed when a dependency module becomes
available and/or replaced. it has the following syntax:

```
module A requires B, C.D
using B
import C.D
# do stuff with B, C.D
# module A will be rerun whenever
# B or C.D are (re)defined
end
```