4 Great changes...

* Adjust font size based on node size
* Start a harmonize draw parameters function
* Add makefile target "runner" to use watchgod to look for Python
  changes
* tolerate 1.1.0 Mathics result type

Author: rocky

Makefile

@@ -22,6 +22,10 @@ build:
 develop:
 	$(PIP) install -e .
 
+#: Run mathicsscript and reload on file changes to the source
+runner:
+	watchgod mathicsscript.__main__.main
+
 #: Install mathicsscript
 install:
 	$(PYTHON) setup.py install

mathicsscript/format.py

@@ -3,6 +3,7 @@
 """
 
 import random
+import math
 import networkx as nx
 
 
@@ -58,6 +59,9 @@ def format_output(obj, expr, format=None):
     return boxes
 
 
+cached_pair = None
+
+
 def hierarchy_pos(
     G, root=None, width=1.0, vert_gap=0.2, vert_loc=0, leaf_vs_root_factor=0.5
 ):
@@ -117,6 +121,10 @@ def hierarchy_pos(
     if not nx.is_tree(G):
         raise TypeError("cannot use hierarchy_pos on a graph that is not a tree")
 
+    global cached_pair
+    if cached_pair is not None:
+        return cached_pair
+
     # These get swapped if tree edge directions point to the root.
     decendants = nx.descendants
     out_degree = G.out_degree if hasattr(G, "out_degree") else G.degree
@@ -247,7 +255,8 @@ def _hierarchy_pos(
         if n <= 0:
             continue
         min_sep = min([x_list[i + 1] - x_list[i] for i in range(n)] + [min_sep])
-    return pos, min_sep
+    cached_pair = pos, min_sep
+    return cached_pair
 
 
 node_size = 300  # this is networkx's default size
@@ -273,6 +282,34 @@ def tree_layout(G):
 }
 
 
+def clamp(value, min=-math.inf, max=math.inf):
+    if value <= min:
+        return min
+    if value >= max:
+        return max
+    return value
+
+
+DEFAULT_NODE_SIZE = 300.0
+DEFAULT_POINT_SIZE = 12
+
+
+def harmonize_parameters(draw_options: dict):
+    if draw_options.get("with_labels", False):
+        draw_options["edgecolors"] = draw_options.get("edgecolors", "black")
+        draw_options["node_color"] = draw_options.get("node_color", "white")
+
+    if "width" not in draw_options:
+        width = clamp(node_size / DEFAULT_NODE_SIZE, min=0.15)
+        draw_options["width"] = width
+
+    if "font_size" not in draw_options:
+        font_size = clamp(
+            int((node_size * DEFAULT_POINT_SIZE) / DEFAULT_NODE_SIZE), min=1, max=18
+        )
+        draw_options["font_size"] = font_size
+
+
 def format_graph(G):
     """
     Format a Graph
@@ -281,12 +318,25 @@ def format_graph(G):
     import matplotlib.pyplot as plt
 
     global node_size
-    node_size = 300  # This is networkx's default
+    global cached_pair
+
+    cached_pair = None
 
     graph_layout = G.graph_layout if hasattr(G, "graph_layout") else None
+
+    node_size = DEFAULT_NODE_SIZE
+    draw_options = {
+        "node_size": node_size,
+        # "with_labels": vertex_labels # Set below
+        # "font_size": 12,        # Harmonized
+        # "node_color": "white",  # Set below
+        # "edgecolors": "black",  # Set below
+        # "width": 5,             # Marmonized
+    }
+
     vertex_labels = G.vertex_labels if hasattr(G, "vertex_labels") else False
     if vertex_labels:
-        vertex_labels = vertex_labels.to_python() or False
+        draw_options["with_labels"] = vertex_labels.to_python() or False
 
     if hasattr(G, "title") and G.title.get_string_value():
         fig, ax = plt.subplots()  # Create a figure and an axes
@@ -296,26 +346,19 @@ def format_graph(G):
         if not isinstance(graph_layout, str):
             graph_layout = graph_layout.get_string_value()
         layout_fn = NETWORKX_LAYOUTS.get(graph_layout, None)
+        if layout_fn == tree_layout:
+            # Call this to compute node_size. Cache the
+            # results
+            tree_layout(G)
+            draw_options["node_size"] = node_size
     else:
         layout_fn = None
 
-    options = {
-        # "font_size": 36,
-        "node_size": node_size,
-        # "node_color": "white",  # Set below
-        # "edgecolors": "black",  # Set below
-        # "linewidths": 5,
-        # "width": 5,
-        "with_labels": vertex_labels,
-    }
-
-    if vertex_labels:
-        options["node_color"] = "white"
-        options["edgecolors"] = "black"
+    harmonize_parameters(draw_options)
 
     if layout_fn:
-        nx.draw(G, pos=layout_fn(G), **options)
+        nx.draw(G, pos=layout_fn(G), **draw_options)
     else:
-        nx.draw_shell(G, **options)
+        nx.draw_shell(G, **draw_options)
     plt.show()
     return None

mathicsscript/termshell.py

@@ -224,10 +224,21 @@ def read_line(self, prompt):
         return input(prompt)
 
     def print_result(self, result, output_style=""):
-        if result is not None and result.last_eval is not None:
+        if result is None:
+            # FIXME decide what to do here
+            return
+
+        # FIXME: after Mathics last_eval is fixed,
+        # we need only the True branch of this code
+        if hasattr(result, "last_eval"):
             last_eval = result.last_eval
-            out_str = str(result.result)
             eval_type = last_eval.get_head_name()
+        else:
+            eval_type = ""
+            last_eval = result.result
+
+        if last_eval is not None:
+            out_str = str(result.result)
             if eval_type == "System`Graph":
                 out_str = "-Graph-"
             elif self.terminal_formatter:  # pygmentize