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