Wip reuse existing instrument rather than error

qcodes/instrument/base.py

@@ -514,6 +514,26 @@ def __call__(cls, *args: Any, **kwargs: Any) -> Any:
  Overloads `type.__call__` to add code that runs only if __init__ completes
  successfully.
  """
+ if len(args) >= 1:
+ name = args[0]
+ else:
+ name = kwargs.get("name", None)
+ existing_instr = None
+ if name is not None:
+
+ try:
+ existing_instr = cls.find_instrument(name, cls) # type: ignore[attr-defined]
+ except (KeyError, TypeError):
+ pass
+
+ if existing_instr is not None:
+ log.info(f"Reusing existing instrument {name}")
+ # todo this is only really safe if this is the same instrument
+ # e.g. address should be the same but that is a trait only implemented
+ # in subclasses
+ return existing_instr
+
+
  new_inst = super().__call__(*args, **kwargs)
  is_abstract = new_inst._is_abstract()
  if is_abstract: