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129 | .\" ======================================================================== | |
130 | .\" | |
131 | .IX Title "FileHandle 3" | |
132 | .TH FileHandle 3 "2002-06-01" "perl v5.8.0" "Perl Programmers Reference Guide" | |
133 | .SH "NAME" | |
134 | FileHandle \- supply object methods for filehandles | |
135 | .SH "SYNOPSIS" | |
136 | .IX Header "SYNOPSIS" | |
137 | .Vb 1 | |
138 | \& use FileHandle; | |
139 | .Ve | |
140 | .PP | |
141 | .Vb 5 | |
142 | \& $fh = new FileHandle; | |
143 | \& if ($fh->open("< file")) { | |
144 | \& print <$fh>; | |
145 | \& $fh->close; | |
146 | \& } | |
147 | .Ve | |
148 | .PP | |
149 | .Vb 5 | |
150 | \& $fh = new FileHandle "> FOO"; | |
151 | \& if (defined $fh) { | |
152 | \& print $fh "bar\en"; | |
153 | \& $fh->close; | |
154 | \& } | |
155 | .Ve | |
156 | .PP | |
157 | .Vb 5 | |
158 | \& $fh = new FileHandle "file", "r"; | |
159 | \& if (defined $fh) { | |
160 | \& print <$fh>; | |
161 | \& undef $fh; # automatically closes the file | |
162 | \& } | |
163 | .Ve | |
164 | .PP | |
165 | .Vb 5 | |
166 | \& $fh = new FileHandle "file", O_WRONLY|O_APPEND; | |
167 | \& if (defined $fh) { | |
168 | \& print $fh "corge\en"; | |
169 | \& undef $fh; # automatically closes the file | |
170 | \& } | |
171 | .Ve | |
172 | .PP | |
173 | .Vb 2 | |
174 | \& $pos = $fh->getpos; | |
175 | \& $fh->setpos($pos); | |
176 | .Ve | |
177 | .PP | |
178 | .Vb 1 | |
179 | \& $fh->setvbuf($buffer_var, _IOLBF, 1024); | |
180 | .Ve | |
181 | .PP | |
182 | .Vb 1 | |
183 | \& ($readfh, $writefh) = FileHandle::pipe; | |
184 | .Ve | |
185 | .PP | |
186 | .Vb 1 | |
187 | \& autoflush STDOUT 1; | |
188 | .Ve | |
189 | .SH "DESCRIPTION" | |
190 | .IX Header "DESCRIPTION" | |
191 | \&\s-1NOTE:\s0 This class is now a front-end to the IO::* classes. | |
192 | .PP | |
193 | \&\f(CW\*(C`FileHandle::new\*(C'\fR creates a \f(CW\*(C`FileHandle\*(C'\fR, which is a reference to a | |
194 | newly created symbol (see the \f(CW\*(C`Symbol\*(C'\fR package). If it receives any | |
195 | parameters, they are passed to \f(CW\*(C`FileHandle::open\*(C'\fR; if the open fails, | |
196 | the \f(CW\*(C`FileHandle\*(C'\fR object is destroyed. Otherwise, it is returned to | |
197 | the caller. | |
198 | .PP | |
199 | \&\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. | |
200 | It requires two parameters, which are passed to \f(CW\*(C`FileHandle::fdopen\*(C'\fR; | |
201 | if the fdopen fails, the \f(CW\*(C`FileHandle\*(C'\fR object is destroyed. | |
202 | Otherwise, it is returned to the caller. | |
203 | .PP | |
204 | \&\f(CW\*(C`FileHandle::open\*(C'\fR accepts one parameter or two. With one parameter, | |
205 | it is just a front end for the built-in \f(CW\*(C`open\*(C'\fR function. With two | |
206 | parameters, the first parameter is a filename that may include | |
207 | whitespace or other special characters, and the second parameter is | |
208 | the open mode, optionally followed by a file permission value. | |
209 | .PP | |
210 | If \f(CW\*(C`FileHandle::open\*(C'\fR receives a Perl mode string (\*(L">\*(R", \*(L"+<\*(R", etc.) | |
211 | or a \s-1POSIX\s0 \fIfopen()\fR mode string (\*(L"w\*(R", \*(L"r+\*(R", etc.), it uses the basic | |
212 | Perl \f(CW\*(C`open\*(C'\fR operator. | |
213 | .PP | |
214 | If \f(CW\*(C`FileHandle::open\*(C'\fR is given a numeric mode, it passes that mode | |
215 | and the optional permissions value to the Perl \f(CW\*(C`sysopen\*(C'\fR operator. | |
216 | For convenience, \f(CW\*(C`FileHandle::import\*(C'\fR tries to import the O_XXX | |
217 | constants from the Fcntl module. If dynamic loading is not available, | |
218 | this may fail, but the rest of FileHandle will still work. | |
219 | .PP | |
220 | \&\f(CW\*(C`FileHandle::fdopen\*(C'\fR is like \f(CW\*(C`open\*(C'\fR except that its first parameter | |
221 | is not a filename but rather a file handle name, a FileHandle object, | |
222 | or a file descriptor number. | |
223 | .PP | |
224 | If the C functions \fIfgetpos()\fR and \fIfsetpos()\fR are available, then | |
225 | \&\f(CW\*(C`FileHandle::getpos\*(C'\fR returns an opaque value that represents the | |
226 | current position of the FileHandle, and \f(CW\*(C`FileHandle::setpos\*(C'\fR uses | |
227 | that value to return to a previously visited position. | |
228 | .PP | |
229 | If the C function \fIsetvbuf()\fR is available, then \f(CW\*(C`FileHandle::setvbuf\*(C'\fR | |
230 | sets the buffering policy for the FileHandle. The calling sequence | |
231 | for the Perl function is the same as its C counterpart, including the | |
232 | macros \f(CW\*(C`_IOFBF\*(C'\fR, \f(CW\*(C`_IOLBF\*(C'\fR, and \f(CW\*(C`_IONBF\*(C'\fR, except that the buffer | |
233 | parameter specifies a scalar variable to use as a buffer. \s-1WARNING:\s0 A | |
234 | variable used as a buffer by \f(CW\*(C`FileHandle::setvbuf\*(C'\fR must not be | |
235 | modified in any way until the FileHandle is closed or until | |
236 | \&\f(CW\*(C`FileHandle::setvbuf\*(C'\fR is called again, or memory corruption may | |
237 | result! | |
238 | .PP | |
239 | See perlfunc for complete descriptions of each of the following | |
240 | supported \f(CW\*(C`FileHandle\*(C'\fR methods, which are just front ends for the | |
241 | corresponding built-in functions: | |
242 | .PP | |
243 | .Vb 8 | |
244 | \& close | |
245 | \& fileno | |
246 | \& getc | |
247 | \& gets | |
248 | \& eof | |
249 | \& clearerr | |
250 | \& seek | |
251 | \& tell | |
252 | .Ve | |
253 | .PP | |
254 | See perlvar for complete descriptions of each of the following | |
255 | supported \f(CW\*(C`FileHandle\*(C'\fR methods: | |
256 | .PP | |
257 | .Vb 12 | |
258 | \& autoflush | |
259 | \& output_field_separator | |
260 | \& output_record_separator | |
261 | \& input_record_separator | |
262 | \& input_line_number | |
263 | \& format_page_number | |
264 | \& format_lines_per_page | |
265 | \& format_lines_left | |
266 | \& format_name | |
267 | \& format_top_name | |
268 | \& format_line_break_characters | |
269 | \& format_formfeed | |
270 | .Ve | |
271 | .PP | |
272 | Furthermore, for doing normal I/O you might need these: | |
273 | .IP "$fh\->print" 4 | |
274 | .IX Item "$fh->print" | |
275 | See \*(L"print\*(R" in perlfunc. | |
276 | .IP "$fh\->printf" 4 | |
277 | .IX Item "$fh->printf" | |
278 | See \*(L"printf\*(R" in perlfunc. | |
279 | .IP "$fh\->getline" 4 | |
280 | .IX Item "$fh->getline" | |
281 | This works like <$fh> described in \*(L"I/O Operators\*(R" in perlop | |
282 | except that it's more readable and can be safely called in a | |
283 | list context but still returns just one line. | |
284 | .IP "$fh\->getlines" 4 | |
285 | .IX Item "$fh->getlines" | |
286 | This works like <$fh> when called in a list context to | |
287 | read all the remaining lines in a file, except that it's more readable. | |
288 | It will also \fIcroak()\fR if accidentally called in a scalar context. | |
289 | .PP | |
290 | There are many other functions available since FileHandle is descended | |
291 | from IO::File, IO::Seekable, and IO::Handle. Please see those | |
292 | respective pages for documentation on more functions. | |
293 | .SH "SEE ALSO" | |
294 | .IX Header "SEE ALSO" | |
295 | The \fB\s-1IO\s0\fR extension, | |
296 | perlfunc, | |
297 | \&\*(L"I/O Operators\*(R" in perlop. |