This is an astute metaphor. In my experience software reuse simplicity strongly depends on the following factors: * interface surface area (i.e. how much of an

This is an astute metaphor. In my experience software reuse simplicity strongly depends on the following factors: * interface surface area (i.e. how much of an interface is exposed) * data types of data coming in and out (static or dynamic). Static languages have an advantage here as many integration constraints can be expressed with types. * whether it is a very focused functionality (e.g. extracting EXIF from file) vs cross-cutting concerns (e.g. logging) The more limited surface area, the simpler the data types and invariants, the more localized it is - the more it is like LEGO as opposed to an organ transplant