add new scenario class decorator for convenience of managing multiple…

… scenarios in process models

biosteam/process_tools/process_model.py

@@ -1,14 +1,69 @@
 # -*- coding: utf-8 -*-
 """
 """
+from dataclasses import dataclass
+__all__ = ('ProcessModel', 'scenario')
 
-__all__ = ('ProcessModel',)
+def display_scenario(scenario):
+    slots = scenario.__slots__
+    units_of_measure = scenario.units_of_measure
+    arguments = []
+    for i in slots:
+        j = getattr(scenario, i)
+        if isinstance(j, (bool, str)):
+            arg = f"{i}={j!r},"
+        else:
+            try:
+                arg = f"{i}={j:.3g},"
+            except:
+                arg = f"{i}={j},"
+        if i in units_of_measure:
+            arg += ' # ' + units_of_measure[i]
+        arguments.append(
+            arg
+        )
+    if arguments:
+        clsname = type(scenario).__name__
+        N_spaces = len(clsname) +1
+        if N_spaces > 4:
+            arguments = '\n    '.join(arguments)
+            print(
+                f"{clsname}("
+                f"\n    {arguments}\n"
+                ")"
+
+            )
+        else:
+            spaces = N_spaces * ' '
+            arguments = f'\n{spaces}'.join(arguments)
+            print(
+                f"{clsname}({arguments})"
+
+            )
+    else:
+        print(
+            f"{type(scenario).__name__}()"
+        )
+
+def scenario(cls=None, **units_of_measure):
+    if cls is None: return lambda cls: scenario(cls, **units_of_measure)
+    cls = dataclass(cls,
+        init=True, repr=True, eq=True, unsafe_hash=False, frozen=True,
+        match_args=True, slots=True,
+    )
+    cls.units_of_measure = units_of_measure
+    cls._ipython_display_ = cls.show = display_scenario
+    return cls
 
 class ProcessModel:
     """Abstract class for setting up an all-in-one handle with easy 
     access to all objects related to a process model, including chemicals, 
     streams, units, systems, and model parameters and metrics."""
 
+    def baseline(self):
+        sample = self.model.get_baseline_sample()
+        return sample, self.model(sample)
+
     def load_system(self, system):
         self.system = system
         self.flowsheet = flowsheet = system.flowsheet