Ruby has no such thing: it's pretty much only used for Rails and plain-jane Unix scripting. It's fair to judge the language in context of its actual applications.
Most, not all: https://www.gnu.org/software/smalltalk/manual/html_node/Over...
Although it looks like somewhere along the path with the "new" graphical browser they dropped the tag line "Smalltalk for those who can type".
Rails is a monster, and historically pretty poor ruby code quality INMHO. That said, ruby does indeed miss an "image" concept, but is quite dynamic and object oriented. Some smalltalk patterns would work well with ruby, I think.
There's also (the abandoned?) maglev ruby on top of gemstone/s object db for smalltalk.