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.TH FileHandle 3 "2001-09-21" "perl v5.8.8" "Perl Programmers Reference Guide"
FileHandle \- supply object methods for filehandles
\& if ($fh->open("< file")) {
\& $fh = new FileHandle "> FOO";
\& $fh = new FileHandle "file", "r";
\& undef $fh; # automatically closes the file
\& $fh = new FileHandle "file", O_WRONLY|O_APPEND;
\& undef $fh; # automatically closes the file
\& $fh->setvbuf($buffer_var, _IOLBF, 1024);
\& ($readfh, $writefh) = FileHandle::pipe;
\&\s-1NOTE:\s0 This class is now a front-end to the IO::* classes.
\&\f(CW\*(C`FileHandle::new\*(C'\fR creates a \f(CW\*(C`FileHandle\*(C'\fR, which is a reference to a
newly created symbol (see the \f(CW\*(C`Symbol\*(C'\fR package). If it receives any
parameters, they are passed to \f(CW\*(C`FileHandle::open\*(C'\fR; if the open fails,
the \f(CW\*(C`FileHandle\*(C'\fR object is destroyed. Otherwise, it is returned to
\&\f(CW\*(C`FileHandle::new_from_fd\*(C'\fR creates a \f(CW\*(C`FileHandle\*(C'\fR like \f(CW\*(C`new\*(C'\fR does.
It requires two parameters, which are passed to \f(CW\*(C`FileHandle::fdopen\*(C'\fR;
if the fdopen fails, the \f(CW\*(C`FileHandle\*(C'\fR object is destroyed.
Otherwise, it is returned to the caller.
\&\f(CW\*(C`FileHandle::open\*(C'\fR accepts one parameter or two. With one parameter,
it is just a front end for the built-in \f(CW\*(C`open\*(C'\fR function. With two
parameters, the first parameter is a filename that may include
whitespace or other special characters, and the second parameter is
the open mode, optionally followed by a file permission value.
If \f(CW\*(C`FileHandle::open\*(C'\fR receives a Perl mode string (\*(L">\*(R", \*(L"+<\*(R", etc.)
or a \s-1POSIX\s0 \fIfopen()\fR mode string (\*(L"w\*(R", \*(L"r+\*(R", etc.), it uses the basic
Perl \f(CW\*(C`open\*(C'\fR operator.
If \f(CW\*(C`FileHandle::open\*(C'\fR is given a numeric mode, it passes that mode
and the optional permissions value to the Perl \f(CW\*(C`sysopen\*(C'\fR operator.
For convenience, \f(CW\*(C`FileHandle::import\*(C'\fR tries to import the O_XXX
constants from the Fcntl module. If dynamic loading is not available,
this may fail, but the rest of FileHandle will still work.
\&\f(CW\*(C`FileHandle::fdopen\*(C'\fR is like \f(CW\*(C`open\*(C'\fR except that its first parameter
is not a filename but rather a file handle name, a FileHandle object,
or a file descriptor number.
If the C functions \fIfgetpos()\fR and \fIfsetpos()\fR are available, then
\&\f(CW\*(C`FileHandle::getpos\*(C'\fR returns an opaque value that represents the
current position of the FileHandle, and \f(CW\*(C`FileHandle::setpos\*(C'\fR uses
that value to return to a previously visited position.
If the C function \fIsetvbuf()\fR is available, then \f(CW\*(C`FileHandle::setvbuf\*(C'\fR
sets the buffering policy for the FileHandle. The calling sequence
for the Perl function is the same as its C counterpart, including the
macros \f(CW\*(C`_IOFBF\*(C'\fR, \f(CW\*(C`_IOLBF\*(C'\fR, and \f(CW\*(C`_IONBF\*(C'\fR, except that the buffer
parameter specifies a scalar variable to use as a buffer. \s-1WARNING:\s0 A
variable used as a buffer by \f(CW\*(C`FileHandle::setvbuf\*(C'\fR must not be
modified in any way until the FileHandle is closed or until
\&\f(CW\*(C`FileHandle::setvbuf\*(C'\fR is called again, or memory corruption may
See perlfunc for complete descriptions of each of the following
supported \f(CW\*(C`FileHandle\*(C'\fR methods, which are just front ends for the
corresponding built-in functions:
See perlvar for complete descriptions of each of the following
supported \f(CW\*(C`FileHandle\*(C'\fR methods:
\& output_field_separator
\& output_record_separator
\& input_record_separator
\& format_line_break_characters
Furthermore, for doing normal I/O you might need these:
See \*(L"print\*(R" in perlfunc.
See \*(L"printf\*(R" in perlfunc.
This works like <$fh> described in \*(L"I/O Operators\*(R" in perlop
except that it's more readable and can be safely called in a
list context but still returns just one line.
This works like <$fh> when called in a list context to
read all the remaining lines in a file, except that it's more readable.
It will also \fIcroak()\fR if accidentally called in a scalar context.
There are many other functions available since FileHandle is descended
from IO::File, IO::Seekable, and IO::Handle. Please see those
respective pages for documentation on more functions.
The \fB\s-1IO\s0\fR extension,
\&\*(L"I/O Operators\*(R" in perlop.