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Document new file() constructor, with the body of open()'s text, plus a 

"new in 2.2" blurb at the end.  Replace open()'s text by pointing back
to file().
This commit is contained in:
Tim Peters 2001-09-20 19:55:29 +00:00
parent f47d8ef683
commit 2e29bfbe1a
1 changed files with 45 additions and 37 deletions
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82
Doc/lib/libfuncs.tex
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@ -252,6 +252,49 @@ class instances are callable if they have a \method{__call__()} method.
\code{None}.
\end{funcdesc}
\begin{funcdesc}{file}{filename\optional{, mode\optional{, bufsize}}}
Return a new file object (described earlier under Built-in Types).
The first two arguments are the same as for \code{stdio}'s
\cfunction{fopen()}: \var{filename} is the file name to be opened,
\var{mode} indicates how the file is to be opened: \code{'r'} for
reading, \code{'w'} for writing (truncating an existing file), and
\code{'a'} opens it for appending (which on \emph{some} \UNIX{}
systems means that \emph{all} writes append to the end of the file,
regardless of the current seek position).
Modes \code{'r+'}, \code{'w+'} and \code{'a+'} open the file for
updating (note that \code{'w+'} truncates the file). Append
\code{'b'} to the mode to open the file in binary mode, on systems
that differentiate between binary and text files (else it is
ignored). If the file cannot be opened, \exception{IOError} is
raised.
If \var{mode} is omitted, it defaults to \code{'r'}. When opening a
binary file, you should append \code{'b'} to the \var{mode} value
for improved portability. (It's useful even on systems which don't
treat binary and text files differently, where it serves as
documentation.)
\index{line-buffered I/O}\index{unbuffered I/O}\index{buffer size, I/O}
\index{I/O control!buffering}
The optional \var{bufsize} argument specifies the
file's desired buffer size: 0 means unbuffered, 1 means line
buffered, any other positive value means use a buffer of
(approximately) that size. A negative \var{bufsize} means to use
the system default, which is usually line buffered for for tty
devices and fully buffered for other files. If omitted, the system
default is used.\footnote{
Specifying a buffer size currently has no effect on systems that
don't have \cfunction{setvbuf()}. The interface to specify the
buffer size is not done using a method that calls
\cfunction{setvbuf()}, because that may dump core when called
after any I/O has been performed, and there's no reliable way to
determine whether this is the case.}
The \function{file()} constructor is new in Python 2.2. The previous
spelling, \function{open()}, is retained for compatibility, and is an
alias for \function{file()}.
\end{funcdesc}
\begin{funcdesc}{filter}{function, list}
Construct a list from those elements of \var{list} for which
\var{function} returns true. \var{list} may be either a sequence, a
@ -479,42 +522,7 @@ the interpreter.
\end{funcdesc}
\begin{funcdesc}{open}{filename\optional{, mode\optional{, bufsize}}}
Return a new file object (described earlier under Built-in Types).
The first two arguments are the same as for \code{stdio}'s
\cfunction{fopen()}: \var{filename} is the file name to be opened,
\var{mode} indicates how the file is to be opened: \code{'r'} for
reading, \code{'w'} for writing (truncating an existing file), and
\code{'a'} opens it for appending (which on \emph{some} \UNIX{}
systems means that \emph{all} writes append to the end of the file,
regardless of the current seek position).
Modes \code{'r+'}, \code{'w+'} and \code{'a+'} open the file for
updating (note that \code{'w+'} truncates the file). Append
\code{'b'} to the mode to open the file in binary mode, on systems
that differentiate between binary and text files (else it is
ignored). If the file cannot be opened, \exception{IOError} is
raised.
If \var{mode} is omitted, it defaults to \code{'r'}. When opening a
binary file, you should append \code{'b'} to the \var{mode} value
for improved portability. (It's useful even on systems which don't
treat binary and text files differently, where it serves as
documentation.)
\index{line-buffered I/O}\index{unbuffered I/O}\index{buffer size, I/O}
\index{I/O control!buffering}
The optional \var{bufsize} argument specifies the
file's desired buffer size: 0 means unbuffered, 1 means line
buffered, any other positive value means use a buffer of
(approximately) that size. A negative \var{bufsize} means to use
the system default, which is usually line buffered for for tty
devices and fully buffered for other files. If omitted, the system
default is used.\footnote{
Specifying a buffer size currently has no effect on systems that
don't have \cfunction{setvbuf()}. The interface to specify the
buffer size is not done using a method that calls
\cfunction{setvbuf()}, because that may dump core when called
after any I/O has been performed, and there's no reliable way to
determine whether this is the case.}
An alias for the \function{file()} function above.
\end{funcdesc}
\begin{funcdesc}{ord}{c}
@ -538,7 +546,7 @@ the interpreter.
\code{10**-2} returns \code{0.01}. (This last feature was added in
Python 2.2. In Python 2.1 and before, if both arguments were of integer
types and the second argument was negative, an exception was raised.)
If the second argument is negative, the third argument must be omitted.
If the second argument is negative, the third argument must be omitted.
If \var{z} is present, \var{x} and \var{y} must be of integer types,
and \var{y} must be non-negative. (This restriction was added in
Python 2.2. In Python 2.1 and before, floating 3-argument \code{pow()}