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| -rw-r--r-- | Doc/lib/libcopy.tex | 60 |
1 files changed, 33 insertions, 27 deletions
diff --git a/Doc/lib/libcopy.tex b/Doc/lib/libcopy.tex index 14e667e..14adbb9 100644 --- a/Doc/lib/libcopy.tex +++ b/Doc/lib/libcopy.tex @@ -4,9 +4,9 @@ \modulesynopsis{Shallow and deep copy operations.} -\setindexsubitem{(copy function)} -\ttindex{copy} -\ttindex{deepcopy} +\withsubitem{(in module copy)}{% + \ttindex{copy}% + \ttindex{deepcopy}} This module provides generic (shallow and deep) copying operations. @@ -19,7 +19,7 @@ x = copy.copy(y) # make a shallow copy of y x = copy.deepcopy(y) # make a deep copy of y \end{verbatim} % -For module specific errors, \code{copy.error} is raised. +For module specific errors, \exception{copy.error} is raised. The difference between shallow and deep copying is only relevant for compound objects (objects that contain other objects, like lists or @@ -49,13 +49,13 @@ Recursive objects (compound objects that, directly or indirectly, contain a reference to themselves) may cause a recursive loop. \item -Because deep copy copies \emph{everything} it may copy too much, e.g.\ -administrative data structures that should be shared even between -copies. +Because deep copy copies \emph{everything} it may copy too much, +e.g., administrative data structures that should be shared even +between copies. \end{itemize} -Python's \code{deepcopy()} operation avoids these problems by: +The \function{deepcopy()} function avoids these problems by: \begin{itemize} @@ -75,24 +75,30 @@ any similar types. Classes can use the same interfaces to control copying that they use to control pickling: they can define methods called -\code{__getinitargs__()}, \code{__getstate__()} and -\code{__setstate__()}. See the description of module \code{pickle} -for information on these methods. -The copy module does not use the \module{copy_reg} registration -module. -\refstmodindex{pickle} -\setindexsubitem{(copy protocol)} -\ttindex{__getinitargs__} -\ttindex{__getstate__} -\ttindex{__setstate__} +\method{__getinitargs__()}, \method{__getstate__()} and +\method{__setstate__()}. See the description of module +\module{pickle}\refstmodindex{pickle} for information on these +methods. The \module{copy} module does not use the \module{copy_reg} +registration module. +\withsubitem{(copy protocol)}{% + \ttindex{__getinitargs__()}% + \ttindex{__getstate__()}% + \ttindex{__setstate__()}} In order for a class to define its own copy implementation, it can -define special methods \method{__copy__()}\ttindex{__copy__} and -\method{__deepcopy__()}\ttindex{__deepcopy__}. The former is called to -implement the shallow copy operation; no additional arguments are -passed. The latter is called to implement the deep copy operation; it -is passed one argument, the memo dictionary. If the -\method{__deepcopy__()} implementation needs to make a deep copy of a -component, it should call the \function{deepcopy()} function with the -component as first argument and the memo dictionary as second -argument. +define special methods \method{__copy__()} and +\method{__deepcopy__()}. The former is called to implement the +shallow copy operation; no additional arguments are passed. The +latter is called to implement the deep copy operation; it is passed +one argument, the memo dictionary. If the \method{__deepcopy__()} +implementation needs to make a deep copy of a component, it should +call the \function{deepcopy()} function with the component as first +argument and the memo dictionary as second argument. +\withsubitem{(copy protocol)}{% + \ttindex{__copy__()}% + \ttindex{__deepcopy__()}} + +\begin{seealso} +\seemodule{pickle}{Discussion of the special disciplines used to +support object state retrieval and restoration.} +\end{seealso} |