Add discussion of factory functions & methods

---
Signed-off-by: Michael Ferguson <mppf@users.noreply.github.com>

doc/rst/developer/bestPractices/StandardModuleStyle.rst

@@ -75,6 +75,33 @@ Many paren-ful methods take some notable action. Try to make these
 methods method names be a verb. In particular, a method that modifies an
 argument in-place should be a verb.
 
+Factory Functions and Methods
++++++++++++++++++++++++++++++
+
+Factory functions or methods are procedures where the main purpose of
+that procedure is to create a new object or value. There are many other
+procedures that return a value but construcing that value is not the main
+purpose of the function. For example, 'open' and 'spawn' are not factory
+functions -- the main action of these methods is to work with the OS to
+open a file or launch a subprocess.
+
+In many cases factory procedures are not needed. Regular initializers
+will work just fine to support the pattern of ``new Something(...)``.
+Type conversion is best supported by creating a cast (``:``) operator
+overload.
+
+One case in which factory procedures are useful is when it is awkward to
+distinguish between several ways of creating something based on the
+initializer arguments alone.
+
+Factory procedures should have a name that begin with 'create'.
+
+Factory procedures can be functions or type methods. For example, we
+could have:
+
+ * ``createStringWithBorrowedBuffer`` or
+ * ``string.createWithBorrowedBuffer``.
+
 Other Identifiers
 -----------------