This triggered some associations for me.
Strongest was Cells[0], a library for Common Lisp CLOS. The earliest reference I can find is 2002[1], making it over 20 years old.
Second is incremental view maintenance systems like Feldera[2] or Materialize[3]. These use sophisticated theories (z-sets and differential dataflow) to apply efficient updates over sets of data, which generalizes the case of single variables.
The third thing I'm reminded of is Modelica[4], a language where variables are connected by relations (in the mathematical sense). So while A = B + C can update A on when B or C change, you also can update just A and B, then find out what C must have become.
[0] https://cells.common-lisp.dev
[1] https://web.archive.org/web/20021216222614/http://www.tilton...