first version

inspector.py

@@ -0,0 +1,98 @@
+import inspect
+import re
+import weakref
+
+import ipywidgets
+
+
+
+HEADER = '<div class="rendered_html jp-RenderedHTMLCommon"><table><thead><tr><th>Name</th><th>Type</th><th>Value</th></tr></thead><tr><td>'
+FOOTER = '</td></tr></table></div>'
+SEP    = '</td></tr><tr><td>'
+LINE   = '{0}</td><td>{1}</td><td>{2}'
+
+IGNORE = ["In", "Out", "exit", "quit", "get_ipython"]
+
+RE_DIGITS = re.compile("([0-9]+)")
+
+
+
+class Singleton(type):
+
+    def __init__(cls, name, bases, namespace):
+        super().__init__(name, bases, namespace) # creates the class
+        cls.__signature__ = inspect.signature(cls.__init__) # restore the constructor signature (instead of that of __call__ below)
+        cls.__instance__ = lambda: None # fake dead weakref
+
+    def __call__(cls, *args, **kwargs):
+        inst = cls.__instance__()
+        if not inst:
+            inst = super().__call__(*args, **kwargs) # creates the instance (calls __new__ and __init__ methods)
+            cls.__instance__ = weakref.ref(inst)
+        return inst
+        
+
+
+class VariableInspector(object, metaclass=Singleton):
+
+    def __init__(self, ipython=None):
+        self._box = ipywidgets.Box()
+        self._box.layout.overflow_y = "scroll"
+        self._table = ipywidgets.HTML(value="Loading...")
+        self._box.children = [self._table]
+
+        self._ipython = ipython or get_ipython()
+        self.start()
+
+
+    def start(self):
+        """Add update callback if not already registered"""
+        if self.is_running:
+            raise RuntimeError("Cannot start. Update callback is already registered")
+        self._ipython.events.register("post_run_cell", self._update)
+
+    def stop(self):
+        """Remove update callback if registered"""
+        if not self.is_running:
+            raise RuntimeError("Cannot stop. Update callback is not registered")
+        self._ipython.events.unregister("post_run_cell", self._update)
+
+    @property
+    def is_running(self):
+        """Test if update callback is registered"""
+        return self._update in self._ipython.events.callbacks["post_run_cell"]
+
+
+    def _update(self, _):
+        """Fill table with variable information"""
+        namespace = self._ipython.user_ns.items()
+        lines = (format_line(k, v) for k, v in sorted_naturally(namespace) if is_good_entry(k, v))
+        self._table.value = HEADER + SEP.join(lines) + FOOTER
+
+    def _ipython_display_(self):
+        """Called when display() or pyout is used to display the Variable Inspector"""
+        try:
+            self._box._ipython_display_()
+        except:
+            pass
+
+
+
+def format_line(k, v):
+    return LINE.format(k, typename(v), v)
+
+def sorted_naturally(iterable, reverse=False):
+    natural = lambda item: [int(c) if c.isdigit() else c.casefold() for c in RE_DIGITS.split(str(item))]
+    return sorted(iterable, key=natural, reverse=reverse)
+
+def is_good_entry(k, v):
+    return not k.startswith("_") and k not in IGNORE and not isinstance(v, VariableInspector)
+
+def typename(obj):
+    return type(obj).__name__
+
+
+
+inspector = VariableInspector()
+
+