feat: allow transient variables to return any kind of data

damnit/ctxsupport/ctxrunner.py

@@ -303,7 +303,10 @@ def execute(self, run_data, run_number, proposal, input_vars) -> 'Results':
                     if annotation.startswith("var#"):
                         dep_name = annotation.removeprefix("var#")
                         if dep_name in res:
-                            kwargs[arg_name] = res[dep_name].data
+                            dep_data = res[dep_name]
+                            if isinstance(dep_data, Cell):
+                                dep_data = dep_data.data
+                            kwargs[arg_name] = dep_data
                         elif param.default is inspect.Parameter.empty:
                             missing_deps.append(dep_name)
 
@@ -343,11 +346,12 @@ def execute(self, run_data, run_number, proposal, input_vars) -> 'Results':
                 if (data := func(run_data)) is None:
                     continue
 
-                if not isinstance(data, Cell):
-                    data = Cell(data)
+                if not var.transient:
+                    if not isinstance(data, Cell):
+                        data = Cell(data)
 
-                if data.summary is None:
-                    data.summary = var.summary
+                    if data.summary is None:
+                        data.summary = var.summary
             except Exception:
                 log.error("Could not get data for %s", name, exc_info=True)
             else:

docs/backend.md

@@ -72,7 +72,8 @@ these arguments:
 - `cluster` (bool): whether or not to execute this variable in a Slurm job. This
   should always be used if the variable does any heavy processing.
 - `transient` (bool): do not save the variable's result to the database. This
-  is useful for e.g. intermediate results to be reused by other Variables. By
+  is useful for e.g. intermediate results to be reused by other Variables. Since
+  their data isn't saved, `transient` variables can return any object. By
   default Variables do save their results (transient=False).
 
 Variable functions can return any of:

tests/test_backend.py

@@ -1019,10 +1019,12 @@ def var1(run):
 
     @Variable(transient=True)
     def var2(run, data: 'var#var1'):
-        return np.arange(data)
+        # transient vars can return any data type
+        return [np.arange(data), run]
 
     @Variable(summary='max')
     def var3(run, data: 'var#var2'):
+        data, run = data
         return data.size * data
     """
     ctx = mkcontext(ctx_code)