Draft: GuiCommandSimplest to serve as base of simple Gui Commands

This class defines the `command_name` of the command,
so that it is output to the report view, and is also recorded
in the log file.

It also stores the current document so it can be used inside the
command.

The class implements with `IsActive` method so that the command
is only active when an active document exists.

Also `GuiCommandNeedsSelection`, which subclasses the former
class. It reimplements `IsActive` in order to be available
only when there is a selection.

src/Mod/Draft/draftguitools/gui_base.py

@@ -30,6 +30,100 @@
 import FreeCAD as App
 import FreeCADGui as Gui
 import draftutils.todo as todo
+from draftutils.messages import _msg, _log
+
+
+class GuiCommandSimplest:
+    """Simplest base class for GuiCommands.
+
+    This class only sets up the command name and the document object
+    to use for the command.
+    When it is executed, it logs the command name to the log file,
+    and prints the command name to the console.
+
+    It implements the `IsActive` method, which must return `True`
+    when the command should be available.
+    It should return `True` when there is an active document,
+    otherwise the command (button or menu) should be disabled.
+
+    This class is meant to be inherited by other GuiCommand classes
+    to quickly log the command name, and set the correct document object.
+
+    Parameter
+    ---------
+    name: str, optional
+        It defaults to `'None'`.
+        The name of the action that is being run,
+        for example, `'Heal'`, `'Flip dimensions'`,
+        `'Line'`, `'Circle'`, etc.
+
+    doc: App::Document, optional
+        It defaults to the value of `App.activeDocument()`.
+        The document object itself, which indicates where the actions
+        of the command will be executed.
+
+    Attributes
+    ----------
+    command_name: str
+        This is the command name, which is assigned by `name`.
+
+    doc: App::Document
+        This is the document object itself, which is assigned by `doc`.
+
+        This attribute should be used by functions to make sure
+        that the operations are performed in the correct document
+        and not in other documents.
+        To set the active document we can use
+
+        >>> App.setActiveDocument(self.doc.Name)
+    """
+
+    def __init__(self, name="None", doc=App.activeDocument()):
+        self.command_name = name
+        self.doc = doc
+
+    def IsActive(self):
+        """Return True when this command should be available.
+
+        It is `True` when there is a document.
+        """
+        if App.activeDocument():
+            return True
+        else:
+            return False
+
+    def Activated(self):
+        """Execute when the command is called.
+
+        Log the command name to the log file and console.
+        Also update the `doc` attribute.
+        """
+        self.doc = App.activeDocument()
+        _log("Document: {}".format(self.doc.Label))
+        _log("GuiCommand: {}".format(self.command_name))
+        _msg("{}".format(16*"-"))
+        _msg("GuiCommand: {}".format(self.command_name))
+
+
+class GuiCommandNeedsSelection(GuiCommandSimplest):
+    """Base class for GuiCommands that need a selection to be available.
+
+    It re-implements the `IsActive` method to return `True`
+    when there is both an active document and an active selection.
+
+    It inherits `GuiCommandSimplest` to set up the document
+    and other behavior. See this class for more information.
+    """
+
+    def IsActive(self):
+        """Return True when this command should be available.
+
+        It is `True` when there is a selection.
+        """
+        if App.activeDocument() and Gui.Selection.getSelection():
+            return True
+        else:
+            return False
 
 
 class GuiCommandSimplest: