cleaned up html_render solution a bit.

Author: PythonCHB

materials/source/notes/session09.rst

@@ -22,9 +22,49 @@ Matthew D Briggs
 Issues that came up during the week.
 ====================================
 
-"private" attributes and dunders...
+"private" attributes and dunders
+--------------------------------
+
+``_something`` vs ``__something`` vs ``__something__``
+
+Adding parameters to a subclass __init__
+----------------------------------------
+
+In general, when you override a method in a subclass, you want the method signature to be the same. That is -- all the parameters should be the same.
+
+
+However, sometimes, particularly with ``__init__``, you may need a couple extra parameters. To keep things clean and extensible, you want to put the extra parameters at the beginning, before the super class' parameters:
+
+And this lets you use ``*args`` and ``**kwargs`` to pass along the usual ones.
+
+.. code-block:: python
+
+    class Base:
+        def __init__(self, par1, par2, par3=something, par4=something):
+            ...
+
+    class Subclass(Base):
+        def __init__(self, newpar1, newpar2, *args, **kwargs):
+            self.newpar1 = newpar1
+            self.newpar2 = newpar2
+            super().__init__(*args, **kwarg)
+
+Example: html_render Anchor tag:
+
+.. code-block:: python
+
+    class A(OneLineTag):
+        """
+        anchor element
+        """
+        tag = "a"
+
+        def __init__(self, link, *args, **kwargs):
+            kwargs['href'] = link
+            super().__init__(*args, **kwargs)
+
+
 
-_ vs __
 
 
 

solutions/Session07/step_5/html_render.py

@@ -103,7 +103,7 @@ class Title(OneLineTag):
 
 class SelfClosingTag(Element):
     """
-    Base class for tags that have no content
+    base class for tags that have no content
     """
 
     def append(self, *args, **kwargs):

solutions/Session07/step_6/html_render.py

@@ -140,9 +140,9 @@ class A(OneLineTag):
     """
     tag = "a"
 
-    def __init__(self, link, content, **kwargs):
+    def __init__(self, link, *args, **kwargs):
         kwargs['href'] = link
-        super().__init__(content, **kwargs)
+        super().__init__(*args, **kwargs)
         # this could also be direct:
-        # Element.__init__(self, content, **kwargs)
+        # Element.__init__(self, *args, **kwargs)
 

solutions/Session07/step_7/html_render.py

@@ -139,11 +139,11 @@ class A(OneLineTag):
     """
     tag = "a"
 
-    def __init__(self, link, content, **kwargs):
+    def __init__(self, link, *args, **kwargs):
         kwargs['href'] = link
-        super().__init__(content, **kwargs)
+        super().__init__(*args, **kwargs)
         # this could also be direct:
-        # Element.__init__(self, content, **kwargs)
+        # Element.__init__(self, *args, **kwargs)
 
 
 class Ul(Element):
@@ -166,6 +166,6 @@ class H(OneLineTag):
     """
     tag = "H"
 
-    def __init__(self, level, content=None, **kwargs):
+    def __init__(self, level, *args, **kwargs):
         self.tag = "h" + str(int(level))
-        super().__init__(content, **kwargs)
+        super().__init__(*args, **kwargs)

solutions/Session07/step_8/html_render.py

@@ -118,9 +118,9 @@ def append(self, *args, **kwargs):
         raise TypeError("You can not add content to a self closing tag")
 
     def render(self, out_file, ind=""):
-        # there is some repition here -- maybe factor that out?
+        # there is some repetition here -- maybe factor that out?
         open_tag, _ = self.make_tags()
-        # make it a self cloding tag by adding the /
+        # make it a self closing tag by adding the /
         out_file.write(ind + open_tag.replace(">", " />"))
 
 
@@ -144,11 +144,11 @@ class A(OneLineTag):
     """
     tag = "a"
 
-    def __init__(self, link, content, **kwargs):
+    def __init__(self, link, *args, **kwargs):
         kwargs['href'] = link
-        super().__init__(content, **kwargs)
+        super().__init__(*args, **kwargs)
         # this could also be direct:
-        # Element.__init__(self, content, **kwargs)
+        # Element.__init__(self, *args, **kwargs)
 
 
 class Ul(Element):
@@ -171,9 +171,9 @@ class H(OneLineTag):
     """
     tag = "H"
 
-    def __init__(self, level, content=None, **kwargs):
+    def __init__(self, level, *args, **kwargs):
         self.tag = "h" + str(int(level))
-        super().__init__(content, **kwargs)
+        super().__init__(*args, **kwargs)
 
 
 class Meta(SelfClosingTag):