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author | Tim Peters <tim.peters@gmail.com> | 2001-10-26 05:06:50 (GMT) |
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committer | Tim Peters <tim.peters@gmail.com> | 2001-10-26 05:06:50 (GMT) |
commit | 1fc240e85150f5cb39502a87cc9a4a0a8cbe5ab0 (patch) | |
tree | d764262205e36bcc61e7cb42895236fdca67c9d3 /Doc | |
parent | b016da3b8391b7401afd95f2c90f5073976c475b (diff) | |
download | cpython-1fc240e85150f5cb39502a87cc9a4a0a8cbe5ab0.zip cpython-1fc240e85150f5cb39502a87cc9a4a0a8cbe5ab0.tar.gz cpython-1fc240e85150f5cb39502a87cc9a4a0a8cbe5ab0.tar.bz2 |
Generalize dictionary() to accept a sequence of 2-sequences. At the
outer level, the iterator protocol is used for memory-efficiency (the
outer sequence may be very large if fully materialized); at the inner
level, PySequence_Fast() is used for time-efficiency (these should
always be sequences of length 2).
dictobject.c, new functions PyDict_{Merge,Update}FromSeq2. These are
wholly analogous to PyDict_{Merge,Update}, but process a sequence-of-2-
sequences argument instead of a mapping object. For now, I left these
functions file static, so no corresponding doc changes. It's tempting
to change dict.update() to allow a sequence-of-2-seqs argument too.
Also changed the name of dictionary's keyword argument from "mapping"
to "x". Got a better name? "mapping_or_sequence_of_pairs" isn't
attractive, although more so than "mosop" <wink>.
abstract.h, abstract.tex: Added new PySequence_Fast_GET_SIZE function,
much faster than going thru the all-purpose PySequence_Size.
libfuncs.tex:
- Document dictionary().
- Fiddle tuple() and list() to admit that their argument is optional.
- The long-winded repetitions of "a sequence, a container that supports
iteration, or an iterator object" is getting to be a PITA. Many
months ago I suggested factoring this out into "iterable object",
where the definition of that could include being explicit about
generators too (as is, I'm not sure a reader outside of PythonLabs
could guess that "an iterator object" includes a generator call).
- Please check my curly braces -- I'm going blind <0.9 wink>.
abstract.c, PySequence_Tuple(): When PyObject_GetIter() fails, leave
its error msg alone now (the msg it produces has improved since
PySequence_Tuple was generalized to accept iterable objects, and
PySequence_Tuple was also stomping on the msg in cases it shouldn't
have even before PyObject_GetIter grew a better msg).
Diffstat (limited to 'Doc')
-rw-r--r-- | Doc/api/abstract.tex | 17 | ||||
-rw-r--r-- | Doc/lib/libfuncs.tex | 26 |
2 files changed, 36 insertions, 7 deletions
diff --git a/Doc/api/abstract.tex b/Doc/api/abstract.tex index 8d271df..fae8475 100644 --- a/Doc/api/abstract.tex +++ b/Doc/api/abstract.tex @@ -125,7 +125,7 @@ for which they do not apply, they will raise a Python exception. the Unicode string representation on success, \NULL{} on failure. This is the equivalent of the Python expression \samp{unistr(\var{o})}. Called by the - \function{unistr()}\bifuncindex{unistr} built-in function. + \function{unistr()}\bifuncindex{unistr} built-in function. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_IsInstance}{PyObject *inst, PyObject *cls} @@ -715,10 +715,17 @@ determination. \begin{cfuncdesc}{PyObject*}{PySequence_Fast_GET_ITEM}{PyObject *o, int i} Return the \var{i}th element of \var{o}, assuming that \var{o} was - returned by \cfunction{PySequence_Fast()}, and that \var{i} is - within bounds. The caller is expected to get the length of the - sequence by calling \cfunction{PySequence_Size()} on \var{o}, since - lists and tuples are guaranteed to always return their true length. + returned by \cfunction{PySequence_Fast()}, \var{o} is not \NULL{}, + and that \var{i} is within bounds. +\end{cfuncdesc} + +\begin{cfuncdesc}{int}{PySequence_Fast_GET_SIZE}{PyObject *o} + Returns the length of \var{o}, assuming that \var{o} was + returned by \cfunction{PySequence_Fast()} and that \var{o} is + not \NULL{}. The size can also be gotten by calling + \cfunction{PySequence_Size()} on \var{o}, but + \cfunction{PySequence_Fast_GET_SIZE()} is faster because it can + assume \var{o} is a list or tuple. \end{cfuncdesc} diff --git a/Doc/lib/libfuncs.tex b/Doc/lib/libfuncs.tex index b19d4a6..e9baeb3 100644 --- a/Doc/lib/libfuncs.tex +++ b/Doc/lib/libfuncs.tex @@ -175,6 +175,28 @@ def my_import(name): \code{del \var{x}.\var{foobar}}. \end{funcdesc} +\begin{funcdesc}{dictionary}{\optional{mapping-or-sequence}} + Return a new dictionary initialized from the optional argument. + If an argument is not specified, return a new empty dictionary. + If the argument is a mapping object, return a dictionary mapping the + same keys to the same values as does the mapping object. + Else the argument must be a sequence, a container that supports + iteration, or an iterator object. The elements of the argument must + each also be of one of those kinds, and each must in turn contain + exactly two objects. The first is used as a key in the new dictionary, + and the second as the key's value. If a given key is seen more than + once, the last value associated with it is retained in the new + dictionary. + For example, these all return a dictionary equal to + \code{\{1: 2, 2: 3\}}: + \code{dictionary(\{1: 2, 2: 3\})}, + \code{dictionary(\{1: 2, 2: 3\}.items()}, + \code{dictionary(\{1: 2, 2: 3\}.iteritems()}, + \code{dictionary(zip((1, 2), (2, 3)))}, + \code{dictionary([[2, 3], [1, 2]])}, and + \code{dictionary([(i-1, i) for i in (2, 3)])}. +\end{funcdesc} + \begin{funcdesc}{dir}{\optional{object}} Without arguments, return the list of names in the current local symbol table. With an argument, attempts to return a list of valid @@ -472,7 +494,7 @@ def my_import(name): may be a sequence (string, tuple or list) or a mapping (dictionary). \end{funcdesc} -\begin{funcdesc}{list}{sequence} +\begin{funcdesc}{list}{\optional{sequence}} Return a list whose items are the same and in the same order as \var{sequence}'s items. \var{sequence} may be either a sequence, a container that supports iteration, or an iterator object. If @@ -726,7 +748,7 @@ def my_import(name): printable string. \end{funcdesc} -\begin{funcdesc}{tuple}{sequence} +\begin{funcdesc}{tuple}{\optional{sequence}} Return a tuple whose items are the same and in the same order as \var{sequence}'s items. \var{sequence} may be a sequence, a container that supports iteration, or an iterator object. |