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| -rw-r--r-- | Doc/lib/libuserdict.tex | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/Doc/lib/libuserdict.tex b/Doc/lib/libuserdict.tex index a27755a..62aff77 100644 --- a/Doc/lib/libuserdict.tex +++ b/Doc/lib/libuserdict.tex @@ -64,6 +64,25 @@ A real Python list object used to store the contents of the \class{UserList} class. \end{memberdesc} +\strong{Subclassing requirements:} +Subclasses of \class{UserList} are expect to offer a constructor which +can be called with either no arguments or one argument. List +operations which return a new sequence attempt to create an instance +of the actual implementation class. To do so, it assumes that the +constructor can be called with a single parameter, which is a sequence +object used as a data source. + +If a derived class does not wish to comply with this requirement, all +of the special methods supported by this class will need to be +overridden; please consult the sources for information about the +methods which need to be provided in that case. + +\versionchanged[Python versions 1.5.2 and 1.6 also required that the + constructor be callable with no parameters, and offer + a mutable \member{data} attribute. Earlier versions + of Python did not attempt to create instances of the + derived class]{2.0} + \section{\module{UserString} --- Class wrapper for string objects} |