[Pather] move render check from __del__ to __exit__ and use render= enum instead of auto_render

examples/tutorial/README.md

@@ -29,7 +29,7 @@ Contents
     * Define a custom `Tool` that exposes primitive routing offers
     * Use primitive offers to automatically transition between path types
 - [renderpather](renderpather.py)
-    * Use `Pather(auto_render=False)` and `PathTool` to build a layout similar to the one in [pather](pather.py),
+    * Use `Pather(render='deferred')` and `PathTool` to build a layout similar to the one in [pather](pather.py),
         but using `Path` shapes instead of `Polygon`s.
 - [port_pather](port_pather.py)
     * Use `PortPather` and the `.at()` syntax for more concise routing

examples/tutorial/port_pather.py

@@ -13,7 +13,7 @@ def main() -> None:
     library, M1_tool, M2_tool = prepare_tools()
 
     # Create a deferred Pather and place some initial pads (same as Pather tutorial)
-    rpather = Pather(library, tools=M2_tool, auto_render=False)
+    rpather = Pather(library, tools=M2_tool, render='deferred')
 
     rpather.place('pad', offset=(18_000, 30_000), port_map={'wire_port': 'VCC'})
     rpather.place('pad', offset=(18_000, 60_000), port_map={'wire_port': 'GND'})
@@ -157,7 +157,7 @@ def main() -> None:
     #
     # Rendering and Saving
     #
-    # Since we deferred auto-rendering, we must call .render() to generate the geometry.
+    # Since routing is deferred, we must call .render() to generate the geometry.
     rpather.render()
 
     library['PortPather_Tutorial'] = rpather.pattern

examples/tutorial/renderpather.py

@@ -13,7 +13,7 @@ def main() -> None:
     #
     #   To illustrate deferred routing with `Pather`, we use `PathTool` instead
     # of `AutoTool`. `PathTool` lacks some sophistication (e.g. no automatic transitions)
-    # but when used with `Pather(auto_render=False)`, it can consolidate multiple routing steps into
+    # but when used with `Pather(render='deferred')`, it can consolidate multiple routing steps into
     # a single `Path` shape.
     #
     #   We'll try to nearly replicate the layout from the `Pather` tutorial; see `pather.py`
@@ -39,7 +39,7 @@ def main() -> None:
     # and what port type to present.
     M1_ptool = PathTool(layer='M1', width=M1_WIDTH, ptype='m1wire')
     M2_ptool = PathTool(layer='M2', width=M2_WIDTH, ptype='m2wire')
-    rpather = Pather(tools=M2_ptool, library=library, auto_render=False)
+    rpather = Pather(tools=M2_ptool, library=library, render='deferred')
 
     # As in the pather tutorial, we make some pads and labels...
     rpather.place('pad', offset=(18_000, 30_000), port_map={'wire_port': 'VCC'})