PackageRequirement needs a relationship with the version
PipRequirement is currently unusable for coala-bears, as it only implement
NpmRequirement isnt much better, as npm install can support version ranges, but only in quotes, and
NpmRequirement doesnt add the quotes, so the caller would need to specify version as a string within a string.
PackageRequirement needs a consistent and usable syntax for the
~= (compatible with) extensively.
It also has one
>=, but that may be replaced with
~=; see https://github.com/coala/coala-bears/issues/1212 .
It is very likely that
<= is needed, for when a bad minor release occurs, but all other version are suitable.
And when a good version comes out after a bad release,
!= is needed.
== (precisely) is the least desirable of all of the relationships, but it wouldnt hurt to have it.