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Text File | 1998-10-28 | 7.0 KB | 265 lines

FFFFiiiilllleeeeHHHHaaaannnnddddlllleeee((((3333)))) 22223333////JJJJuuuullll////99998888 ((((ppppeeeerrrrllll 5555....000000005555,,,, ppppaaaattttcccchhhh 00002222)))) FFFFiiiilllleeeeHHHHaaaannnnddddlllleeee((((3333)))) NNNNAAAAMMMMEEEE FileHandle - supply object methods for filehandles SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS use FileHandle; $fh = new FileHandle; if ($fh->open("< file")) { print <$fh>; $fh->close; } $fh = new FileHandle "> FOO"; if (defined $fh) { print $fh "bar\n"; $fh->close; } $fh = new FileHandle "file", "r"; if (defined $fh) { print <$fh>; undef $fh; # automatically closes the file } $fh = new FileHandle "file", O_WRONLY|O_APPEND; if (defined $fh) { print $fh "corge\n"; undef $fh; # automatically closes the file } $pos = $fh->getpos; $fh->setpos($pos); $fh->setvbuf($buffer_var, _IOLBF, 1024); ($readfh, $writefh) = FileHandle::pipe; autoflush STDOUT 1; DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN NOTE: This class is now a front-end to the IO::* classes. FileHandle::new creates a FileHandle, which is a reference to a newly created symbol (see the Symbol package). If it receives any parameters, they are passed to FileHandle::open; if the open fails, the FileHandle object is destroyed. Otherwise, it is returned to the caller. FileHandle::new_from_fd creates a FileHandle like new does. It requires two parameters, which are passed to FileHandle::fdopen; if the fdopen fails, the FileHandle Page 1 (printed 10/23/98) FFFFiiiilllleeeeHHHHaaaannnnddddlllleeee((((3333)))) 22223333////JJJJuuuullll////99998888 ((((ppppeeeerrrrllll 5555....000000005555,,,, ppppaaaattttcccchhhh 00002222)))) FFFFiiiilllleeeeHHHHaaaannnnddddlllleeee((((3333)))) object is destroyed. Otherwise, it is returned to the caller. FileHandle::open accepts one parameter or two. With one parameter, it is just a front end for the built-in open 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 FileHandle::open receives a Perl mode string (">", "+<", etc.) or a POSIX _f_o_p_e_n() mode string ("w", "r+", etc.), it uses the basic Perl open operator. If FileHandle::open is given a numeric mode, it passes that mode and the optional permissions value to the Perl sysopen operator. For convenience, FileHandle::import 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. FileHandle::fdopen is like open 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 _f_g_e_t_p_o_s() and _f_s_e_t_p_o_s() are available, then FileHandle::getpos returns an opaque value that represents the current position of the FileHandle, and FileHandle::setpos uses that value to return to a previously visited position. If the C function _s_e_t_v_b_u_f() is available, then FileHandle::setvbuf sets the buffering policy for the FileHandle. The calling sequence for the Perl function is the same as its C counterpart, including the macros _IOFBF, _IOLBF, and _IONBF, except that the buffer parameter specifies a scalar variable to use as a buffer. WARNING: A variable used as a buffer by FileHandle::setvbuf must not be modified in any way until the FileHandle is closed or until FileHandle::setvbuf is called again, or memory corruption may result! See the _p_e_r_l_f_u_n_c manpage for complete descriptions of each of the following supported FileHandle methods, which are just front ends for the corresponding built-in functions: Page 2 (printed 10/23/98) FFFFiiiilllleeeeHHHHaaaannnnddddlllleeee((((3333)))) 22223333////JJJJuuuullll////99998888 ((((ppppeeeerrrrllll 5555....000000005555,,,, ppppaaaattttcccchhhh 00002222)))) FFFFiiiilllleeeeHHHHaaaannnnddddlllleeee((((3333)))) close fileno getc gets eof clearerr seek tell See the _p_e_r_l_v_a_r manpage for complete descriptions of each of the following supported FileHandle methods: autoflush output_field_separator output_record_separator input_record_separator input_line_number format_page_number format_lines_per_page format_lines_left format_name format_top_name format_line_break_characters format_formfeed Furthermore, for doing normal I/O you might need these: $fh->print See the print entry in the _p_e_r_l_f_u_n_c manpage. $fh->printf See the printf entry in the _p_e_r_l_f_u_n_c manpage. $fh->getline This works like <$fh> described in the section on _I/_O _O_p_e_r_a_t_o_r_s in the _p_e_r_l_o_p manpage except that it's more readable and can be safely called in an array context but still returns just one line. $fh->getlines This works like <$fh> when called in an array context to read all the remaining lines in a file, except that it's more readable. It will also _c_r_o_a_k() 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. SSSSEEEEEEEE AAAALLLLSSSSOOOO The IIIIOOOO extension, the _p_e_r_l_f_u_n_c manpage, the section on _I/_O Page 3 (printed 10/23/98) FFFFiiiilllleeeeHHHHaaaannnnddddlllleeee((((3333)))) 22223333////JJJJuuuullll////99998888 ((((ppppeeeerrrrllll 5555....000000005555,,,, ppppaaaattttcccchhhh 00002222)))) FFFFiiiilllleeeeHHHHaaaannnnddddlllleeee((((3333)))) _O_p_e_r_a_t_o_r_s in the _p_e_r_l_o_p manpage. Page 4 (printed 10/23/98)