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| author | Guido van Rossum <guido@python.org> | 1995-03-16 14:44:07 (GMT) |
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| committer | Guido van Rossum <guido@python.org> | 1995-03-16 14:44:07 (GMT) |
| commit | a54754719d5f44a898b549ae8ad6940f5a04ed42 (patch) | |
| tree | c7855f7c1e0f55eab99ddf6e7e58523daae8b564 /Doc/ref5.tex | |
| parent | a521c1b751c631049a052d9e8103f355b1c1b248 (diff) | |
| download | cpython-a54754719d5f44a898b549ae8ad6940f5a04ed42.zip cpython-a54754719d5f44a898b549ae8ad6940f5a04ed42.tar.gz cpython-a54754719d5f44a898b549ae8ad6940f5a04ed42.tar.bz2 | |
made palatable for latex2html:
removed $math$, added braces to \item[\tt...]
Diffstat (limited to 'Doc/ref5.tex')
| -rw-r--r-- | Doc/ref5.tex | 69 |
1 files changed, 37 insertions, 32 deletions
diff --git a/Doc/ref5.tex b/Doc/ref5.tex index af385aa..3db2528 100644 --- a/Doc/ref5.tex +++ b/Doc/ref5.tex @@ -307,9 +307,10 @@ The primary must evaluate to a sequence object. The lower and upper bound expressions, if present, must evaluate to plain integers; defaults are zero and the sequence's length, respectively. If either bound is negative, the sequence's length is added to it. The slicing -now selects all items with index $k$ such that $i <= k < j$ where $i$ -and $j$ are the specified lower and upper bounds. This may be an -empty sequence. It is not an error if $i$ or $j$ lie outside the +now selects all items with index \var{k} such that +\code{\var{i} <= \var{k} < \var{j}} where \var{i} +and \var{j} are the specified lower and upper bounds. This may be an +empty sequence. It is not an error if \var{i} or \var{j} lie outside the range of valid indexes (such items don't exist so they aren't selected). @@ -477,10 +478,11 @@ arguments are converted to a common type. They shift the first argument to the left or right by the number of bits given by the second argument. -A right shift by $n$ bits is defined as division by $2^n$. A left -shift by $n$ bits is defined as multiplication with $2^n$; for plain -integers there is no overflow check so this drops bits and flip the -sign if the result is not less than $2^{31}$ in absolute value. +A right shift by \var{n} bits is defined as division by +\code{pow(2,\var{n})}. A left shift by \var{n} bits is defined as +multiplication with \code{pow(2,\var{n})}; for plain integers there is +no overflow check so this drops bits and flips the sign if the result +is not less than \code{pow(2,31)} in absolute value. Negative shift counts raise a \verb@ValueError@ exception. \exindex{ValueError} @@ -530,20 +532,21 @@ comp_operator: "<"|">"|"=="|">="|"<="|"<>"|"!="|"is" ["not"]|["not"] "in" Comparisons yield integer values: 1 for true, 0 for false. -Comparisons can be chained arbitrarily, e.g. $x < y <= z$ is -equivalent to $x < y$ \verb@and@ $y <= z$, except that $y$ is -evaluated only once (but in both cases $z$ is not evaluated at all -when $x < y$ is found to be false). +Comparisons can be chained arbitrarily, e.g. \code{x < y <= z} is +equivalent to \code{x < y and y <= z}, except that \code{y} is +evaluated only once (but in both cases \code{z} is not evaluated at all +when \code{x < y} is found to be false). \indexii{chaining}{comparisons} -\catcode`\_=8 -Formally, $e_0 op_1 e_1 op_2 e_2 ...e_{n-1} op_n e_n$ is equivalent to -$e_0 op_1 e_1$ \verb@and@ $e_1 op_2 e_2$ \verb@and@ ... \verb@and@ -$e_{n-1} op_n e_n$, except that each expression is evaluated at most once. +Formally, if \var{a}, \var{b}, \var{c}, \ldots, \var{y}, \var{z} are +expressions and \var{opa}, \var{opb}, \ldots, \var{opy} are comparison +operators, then \var{a opa b opb c} \ldots \var{y opy z} is equivalent +to \var{a opa b} \code{and} \var{b opb c} \code{and} \ldots \code{and} +\var{y opy z}, except that each expression is evaluated at most once. -Note that $e_0 op_1 e_1 op_2 e_2$ does not imply any kind of comparison -between $e_0$ and $e_2$, e.g. $x < y > z$ is perfectly legal. -\catcode`\_=12 +Note that \var{a opa b opb c} doesn't imply any kind of comparison +between \var{a} and \var{c}, so that e.g.\ \code{x < y > z} is +perfectly legal (though perhaps not pretty). The forms \verb@<>@ and \verb@!=@ are equivalent; for consistency with C, \verb@!=@ is preferred; where \verb@!=@ is mentioned below @@ -557,7 +560,7 @@ ordered consistently but arbitrarily. (This unusual definition of comparison is done to simplify the definition of operations like sorting and the \verb@in@ and -\verb@not in@ operators.) +\verb@not@ \verb@in@ operators.) Comparison of objects of the same type depends on the type: @@ -592,11 +595,12 @@ execution of a program. \end{itemize} The operators \verb@in@ and \verb@not in@ test for sequence -membership: if $y$ is a sequence, $x ~\verb@in@~ y$ is true if and -only if there exists an index $i$ such that $x = y[i]$. -$x ~\verb@not in@~ y$ yields the inverse truth value. The exception -\verb@TypeError@ is raised when $y$ is not a sequence, or when $y$ is -a string and $x$ is not a string of length one.% +membership: if \var{y} is a sequence, \code{\var{x} in \var{y}} is +true if and only if there exists an index \var{i} such that +\code{\var{x} = \var{y}[\var{i}]}. +\code{\var{x} not in \var{y}} yields the inverse truth value. The +exception \verb@TypeError@ is raised when \var{y} is not a sequence, +or when \var{y} is a string and \var{x} is not a string of length one.% \footnote{The latter restriction is sometimes a nuisance.} \opindex{in} \opindex{not in} @@ -604,8 +608,9 @@ a string and $x$ is not a string of length one.% \obindex{sequence} The operators \verb@is@ and \verb@is not@ test for object identity: -$x ~\verb@is@~ y$ is true if and only if $x$ and $y$ are the same -object. $x ~\verb@is not@~ y$ yields the inverse truth value. +\var{x} \code{is} \var{y} is true if and only if \var{x} and \var{y} +are the same object. \var{x} \code{is not} \var{y} yields the inverse +truth value. \opindex{is} \opindex{is not} \indexii{identity}{test} @@ -632,14 +637,14 @@ other values are interpreted as true. The operator \verb@not@ yields 1 if its argument is false, 0 otherwise. \opindex{not} -The condition $x ~\verb@and@~ y$ first evaluates $x$; if $x$ is false, -its value is returned; otherwise, $y$ is evaluated and the resulting -value is returned. +The condition \var{x} \verb@and@ \var{y} first evaluates \var{x}; if +\var{x} is false, its value is returned; otherwise, \var{y} is +evaluated and the resulting value is returned. \opindex{and} -The condition $x ~\verb@or@~ y$ first evaluates $x$; if $x$ is true, -its value is returned; otherwise, $y$ is evaluated and the resulting -value is returned. +The condition \var{x} \verb@or@ \var{y} first evaluates \var{x}; if +\var{x} is true, its value is returned; otherwise, \var{y} is +evaluated and the resulting value is returned. \opindex{or} (Note that \verb@and@ and \verb@or@ do not restrict the value and type |