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| -rw-r--r-- | Doc/ref/ref3.tex | 107 |
1 files changed, 56 insertions, 51 deletions
diff --git a/Doc/ref/ref3.tex b/Doc/ref/ref3.tex index c453b85..1f3afbf 100644 --- a/Doc/ref/ref3.tex +++ b/Doc/ref/ref3.tex @@ -1233,22 +1233,24 @@ object is created instead, and passed to \method{__getitem__()} instead. Called to implement assignment to \code{\var{self}[\var{i}:\var{j}]}. Same notes for \var{i} and \var{j} as for \method{__getslice__()}. -This method is deprecated. If no \method{__setslice__()} is found, a slice -object is created instead, and passed to \method{__setitem__()} instead. +This method is deprecated. If no \method{__setslice__()} is found, a +slice object is created instead, and passed to \method{__setitem__()} +instead. \end{methoddesc} \begin{methoddesc}[sequence object]{__delslice__}{self, i, j} Called to implement deletion of \code{\var{self}[\var{i}:\var{j}]}. Same notes for \var{i} and \var{j} as for \method{__getslice__()}. -This method is deprecated. If no \method{__delslice__()} is found, a slice -object is created instead, and passed to \method{__delitem__()} instead. +This method is deprecated. If no \method{__delslice__()} is found, a +slice object is created instead, and passed to \method{__delitem__()} +instead. \end{methoddesc} -Notice that these methods are only invoked when a single slice with a single -colon is used, and the slice method is available. For slice operations -involving extended slice notation, or in absence of the slice methods, -\method{__getitem__()}, \method{__setitem__()} or \method{__delitem__()} is -called with a slice object as argument. +Notice that these methods are only invoked when a single slice with a +single colon is used, and the slice method is available. For slice +operations involving extended slice notation, or in absence of the +slice methods, \method{__getitem__()}, \method{__setitem__()} or +\method{__delitem__()} is called with a slice object as argument. The following example demonstrate how to make your program or module compatible with earlier versions of Python (assuming that methods @@ -1326,10 +1328,10 @@ These functions are called to implement the binary arithmetic operations (\code{+}, \code{-}, \code{*}, \code{/}, \code{\%}, \function{divmod()}\bifuncindex{divmod}, -\function{pow()}\bifuncindex{pow}, \code{**}, \code{<<}, \code{>>}, -\code{\&}, \code{\^}, \code{|}). For instance, to evaluate the -expression \var{x}\code{+}\var{y}, where \var{x} is an instance of a -class that has an \method{__add__()} method, +\function{pow()}\bifuncindex{pow}, \code{**}, \code{<}\code{<}, +\code{>}\code{>}, \code{\&}, \code{\^}, \code{|}). For instance, to +evaluate the expression \var{x}\code{+}\var{y}, where \var{x} is an +instance of a class that has an \method{__add__()} method, \code{\var{x}.__add__(\var{y})} is called. Note that \method{__pow__()} should be defined to accept an optional third argument if the ternary version of the built-in @@ -1352,14 +1354,15 @@ These functions are called to implement the binary arithmetic operations (\code{+}, \code{-}, \code{*}, \code{/}, \code{\%}, \function{divmod()}\bifuncindex{divmod}, -\function{pow()}\bifuncindex{pow}, \code{**}, \code{<<}, \code{>>}, -\code{\&}, \code{\^}, \code{|}) with reflected (swapped) operands. These -functions are only called if the left operand does not support the -corresponding operation. For instance, to evaluate the expression -\var{x}\code{-}\var{y}, where \var{y} is an instance of a class that -has an \method{__rsub__()} method, \code{\var{y}.__rsub__(\var{x})} is -called. Note that ternary \function{pow()}\bifuncindex{pow} will not -try calling \method{__rpow__()} (the coercion rules would become too +\function{pow()}\bifuncindex{pow}, \code{**}, \code{<}\code{<}, +\code{>}\code{>}, \code{\&}, \code{\^}, \code{|}) with reflected +(swapped) operands. These functions are only called if the left +operand does not support the corresponding operation. For instance, +to evaluate the expression \var{x}\code{-}\var{y}, where \var{y} is an +instance of a class that has an \method{__rsub__()} method, +\code{\var{y}.__rsub__(\var{x})} is called. Note that ternary +\function{pow()}\bifuncindex{pow} will not try calling +\method{__rpow__()} (the coercion rules would become too complicated). \end{methoddesc} @@ -1374,27 +1377,28 @@ complicated). \methodline[numeric object]{__iand__}{self, other} \methodline[numeric object]{__ixor__}{self, other} \methodline[numeric object]{__ior__}{self, other} -These methods are called to implement the augmented arithmetic operations -(\code{+=}, \code{-=}, \code{*=}, \code{/=}, \code{\%=}, \code{**=}, -\code{<<=}, \code{>>=}, \code{\&=}, \code{\^=}, \code{|=}). These methods -should attempt to do the operation in-place (modifying \var{self}) and -return the result (which could be, but does not have to be, \var{self}). If -a specific method is not defined, the augmented operation falls back to the -normal methods. For instance, to evaluate the expression -\var{x}\code{+=}\var{y}, where \var{x} is an instance of a class that has an -\method{__iadd__()} method, \code{\var{x}.__iadd__(\var{y})} is called. If -\var{x} is an instance of a class that does not define a \method{__iadd()} -method, \code{\var{x}.__add__(\var{y})} and \code{\var{y}.__radd__(\var{x})} -are considered, as with the evaluation of \var{x}\code{+}\var{y}. - +These methods are called to implement the augmented arithmetic +operations (\code{+=}, \code{-=}, \code{*=}, \code{/=}, \code{\%=}, +\code{**=}, \code{<}\code{<=}, \code{>}\code{>=}, \code{\&=}, +\code{\^=}, \code{|=}). These methods should attempt to do the +operation in-place (modifying \var{self}) and return the result (which +could be, but does not have to be, \var{self}). If a specific method +is not defined, the augmented operation falls back to the normal +methods. For instance, to evaluate the expression +\var{x}\code{+=}\var{y}, where \var{x} is an instance of a class that +has an \method{__iadd__()} method, \code{\var{x}.__iadd__(\var{y})} is +called. If \var{x} is an instance of a class that does not define a +\method{__iadd()} method, \code{\var{x}.__add__(\var{y})} and +\code{\var{y}.__radd__(\var{x})} are considered, as with the +evaluation of \var{x}\code{+}\var{y}. \end{methoddesc} \begin{methoddesc}[numeric object]{__neg__}{self} \methodline[numeric object]{__pos__}{self} \methodline[numeric object]{__abs__}{self} \methodline[numeric object]{__invert__}{self} -Called to implement the unary arithmetic operations (\code{-}, \code{+}, -\function{abs()}\bifuncindex{abs} and \code{\~{}}). +Called to implement the unary arithmetic operations (\code{-}, +\code{+}, \function{abs()}\bifuncindex{abs} and \code{\~{}}). \end{methoddesc} \begin{methoddesc}[numeric object]{__complex__}{self} @@ -1427,17 +1431,17 @@ the other type here). \end{methoddesc} \strong{Coercion rules}: to evaluate \var{x} \var{op} \var{y}, the -following steps are taken (where \method{__op__()} and -\method{__rop__()} are the method names corresponding to \var{op}, -e.g., if var{op} is `\code{+}', \method{__add__()} and +following steps are taken (where \method{__\var{op}__()} and +\method{__r\var{op}__()} are the method names corresponding to +\var{op}, e.g., if \var{op} is `\code{+}', \method{__add__()} and \method{__radd__()} are used). If an exception occurs at any point, the evaluation is abandoned and exception handling takes over. \begin{itemize} -\item[0.] If \var{x} is a string object and op is the modulo operator (\%), -the string formatting operation is invoked and the remaining steps are -skipped. +\item[0.] If \var{x} is a string object and \var{op} is the modulo + operator (\%), the string formatting operation is invoked and + the remaining steps are skipped. \item[1.] If \var{x} is a class instance: @@ -1451,8 +1455,8 @@ skipped. \item[1b.] If neither \var{x} nor \var{y} is a class instance after coercion, go to step 3. - \item[1c.] If \var{x} has a method \method{__op__()}, return - \code{\var{x}.__op__(\var{y})}; otherwise, restore \var{x} and + \item[1c.] If \var{x} has a method \method{__\var{op}__()}, return + \code{\var{x}.__\var{op}__(\var{y})}; otherwise, restore \var{x} and \var{y} to their value before step 1a. \end{itemize} @@ -1469,9 +1473,9 @@ skipped. \item[2b.] If neither \var{x} nor \var{y} is a class instance after coercion, go to step 3. - \item[2b.] If \var{y} has a method \method{__rop__()}, return - \code{\var{y}.__rop__(\var{x})}; otherwise, restore \var{x} - and \var{y} to their value before step 2a. + \item[2b.] If \var{y} has a method \method{__r\var{op}__()}, + return \code{\var{y}.__r\var{op}__(\var{x})}; otherwise, + restore \var{x} and \var{y} to their value before step 2a. \end{itemize} @@ -1480,11 +1484,12 @@ instance. \begin{itemize} - \item[3a.] If op is `\code{+}' and \var{x} is a sequence, - sequence concatenation is invoked. + \item[3a.] If \var{op} is `\code{+}' and \var{x} is a + sequence, sequence concatenation is invoked. - \item[3b.] If op is `\code{*}' and one operand is a sequence - and the other an integer, sequence repetition is invoked. + \item[3b.] If \var{op} is `\code{*}' and one operand is a + sequence and the other an integer, sequence repetition is + invoked. \item[3c.] Otherwise, both operands must be numbers; they are coerced to a common type if possible, and the numeric |