I made it to help me orient myself in unfamiliar legacy code and to help identify cohesive parts that could be split out.
Yes, it is quick and dirty.
ExampleOne file in YaST has around 2700 lines and 73 methods. The call graph below was made with
If the resulting size is too big, use ImageMagick:
$ ./call-graph ../yast/packager/src/modules/Packages.rb $ dot -Tpng -oPackages.png ../yast/packager/src/modules/Packages.dot
$ convert Packages.png -resize 1200 Packages-small.png