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GeezerVison is showing github.com — doc-en/reference/errorfunc/functions/set-error-handler.xml at master · php/doc-en Expand file tree/ Copy pathset-error-handler.xmlMore file actions 436 lines (409 loc) · 14.4 KB / Copy pathset-error-handler.xmlFile metadata and controls436 lines (409 loc) · 14.4 KB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 <?xml version="1.0" encoding="utf-8"?> <!-- $Revision$ --> <refentry xml:id="function.set-error-handler" xmlns="http://docbook.org/ns/docbook"> <refnamediv> <refname>set_error_handler</refname> <refpurpose>Sets a user-defined error handler function</refpurpose> </refnamediv> <refsect1 role="description"> &reftitle.description; <methodsynopsis> <type class="union"><type>callable</type><type>null</type></type><methodname>set_error_handler</methodname> <methodparam><type class="union"><type>callable</type><type>null</type></type><parameter>callback</parameter></methodparam> <methodparam choice="opt"><type>int</type><parameter>error_levels</parameter><initializer><constant>E_ALL</constant></initializer></methodparam> </methodsynopsis> <simpara> Sets a user function (<parameter>callback</parameter>) to handle errors in a script. The handler that was active until then is saved on an internal stack of error handlers, from which <function>restore_error_handler</function> pops it back. </simpara> <para> This function can be used to define custom error handlers during runtime, for example in applications which need to do file/data cleanup when a critical error happens, or when triggering an error in response to certain conditions (using <function>trigger_error</function>). </para> <para> It is important to remember that the standard PHP error handler is completely bypassed for the error types specified by <parameter>error_levels</parameter> unless the callback function returns &false;. <function>error_reporting</function> settings will have no effect and the error handler will be called regardless - however, it's still possible to read the current value of <link linkend="ini.error-reporting">error_reporting</link> and act appropriately. </para> <para> Also note that it is the handler's responsibility to stop the script's execution if necessary by calling <function>exit</function>. If the error-handler function returns, script execution will continue with the next statement after the one that caused an error. </para> <para> The following error types cannot be handled with a user defined function: <constant>E_ERROR</constant>, <constant>E_PARSE</constant>, <constant>E_CORE_ERROR</constant>, <constant>E_CORE_WARNING</constant>, <constant>E_COMPILE_ERROR</constant>, <constant>E_COMPILE_WARNING</constant> independent of where they were raised, and most of <constant>E_STRICT</constant> raised in the file where <function>set_error_handler</function> is called. </para> <para> If errors occur before the script is executed (e.g. on file uploads) the custom error handler cannot be called since it is not registered at that time. </para> </refsect1> <refsect1 role="parameters"> &reftitle.parameters; <para> <variablelist> <varlistentry> <term><parameter>callback</parameter></term> <listitem> <simpara> If &null; is passed, no user-defined handler is left active and errors fall back to the built-in error handler. The handler that was active until then is still saved on the stack and can be brought back with <function>restore_error_handler</function>. Otherwise, the handler is a callback with the following signature: </simpara> <para> <methodsynopsis> <type>bool</type><methodname><replaceable>handler</replaceable></methodname> <methodparam><type>int</type><parameter>errno</parameter></methodparam> <methodparam><type>string</type><parameter>errstr</parameter></methodparam> <methodparam choice="opt"><type>string</type><parameter>errfile</parameter></methodparam> <methodparam choice="opt"><type>int</type><parameter>errline</parameter></methodparam> <methodparam choice="opt"><type>array</type><parameter>errcontext</parameter></methodparam> </methodsynopsis> <variablelist> <varlistentry> <term><parameter>errno</parameter></term> <listitem> <simpara> The first parameter, <parameter>errno</parameter>, will be passed the level of the error raised, as an integer. </simpara> </listitem> </varlistentry> <varlistentry> <term><parameter>errstr</parameter></term> <listitem> <simpara> The second parameter, <parameter>errstr</parameter>, will be passed the error message, as a string. </simpara> </listitem> </varlistentry> <varlistentry> <term><parameter>errfile</parameter></term> <listitem> <simpara> If the callback accepts a third parameter, <parameter>errfile</parameter>, it will be passed the filename that the error was raised in, as a string. </simpara> </listitem> </varlistentry> <varlistentry> <term><parameter>errline</parameter></term> <listitem> <simpara> If the callback accepts a fourth parameter, <parameter>errline</parameter>, it will be passed the line number where the error was raised, as an integer. </simpara> </listitem> </varlistentry> <varlistentry> <term><parameter>errcontext</parameter></term> <listitem> <simpara> If the callback accepts a fifth parameter, <parameter>errcontext</parameter>, it will be passed an array that points to the active symbol table at the point the error occurred. In other words, <parameter>errcontext</parameter> will contain an array of every variable that existed in the scope the error was triggered in. User error handlers must not modify the error context. </simpara> <warning xmlns="http://docbook.org/ns/docbook"> <simpara> This parameter has been <emphasis>DEPRECATED</emphasis> as of PHP 7.2.0, and <emphasis>REMOVED</emphasis> as of PHP 8.0.0. If the function defines this parameter without a default, an error of "too few arguments" will be raised when it is called. </simpara> </warning> </listitem> </varlistentry> </variablelist> </para> <para> If the function returns &false; then the normal error handler continues. </para> </listitem> </varlistentry> <varlistentry> <term><parameter>error_levels</parameter></term> <listitem> <para> Can be used to mask the triggering of the <parameter>callback</parameter> function just like the <link linkend="ini.error-reporting">error_reporting</link> ini setting controls which errors are shown. Without this mask set the <parameter>callback</parameter> will be called for every error regardless to the setting of the <link linkend="ini.error-reporting">error_reporting</link> setting. </para> </listitem> </varlistentry> </variablelist> </para> </refsect1> <refsect1 role="returnvalues"> &reftitle.returnvalues; <para> Returns the previously defined error handler (if any) as a <type>callable</type>. If the built-in error handler is used &null; is returned. </para> </refsect1> <refsect1 role="changelog"> &reftitle.changelog; <para> <informaltable> <tgroup cols="2"> <thead> <row> <entry>&Version;</entry> <entry>&Description;</entry> </row> </thead> <tbody> <row> <entry>8.0.0</entry> <entry> <parameter>errcontext</parameter> was removed, and will no longer be passed to user callbacks. </entry> </row> <row> <entry>7.2.0</entry> <entry> <parameter>errcontext</parameter> became deprecated. Usage of this parameter now emits an <constant>E_DEPRECATED</constant> notice. </entry> </row> </tbody> </tgroup> </informaltable> </para> </refsect1> <refsect1 role="examples"> &reftitle.examples; <para> <example> <title>Error handling with <function>set_error_handler</function> and <function>trigger_error</function></title> <para> The example below shows the handling of internal exceptions by triggering errors and handling them with a user defined function: </para> <programlisting role="php"> <![CDATA[ <?php // error handler function function myErrorHandler($errno, $errstr, $errfile, $errline) { if (!(error_reporting() & $errno)) { // This error code is not included in error_reporting, so let it fall // through to the standard PHP error handler return false; } // $errstr may need to be escaped: $errstr = htmlspecialchars($errstr); switch ($errno) { case E_USER_ERROR: echo "<b>My ERROR</b> [$errno] $errstr<br />\n"; echo " Fatal error on line $errline in file $errfile"; echo ", PHP " . PHP_VERSION . " (" . PHP_OS . ")<br />\n"; echo "Aborting...<br />\n"; exit(1); case E_USER_WARNING: echo "<b>My WARNING</b> [$errno] $errstr<br />\n"; break; case E_USER_NOTICE: echo "<b>My NOTICE</b> [$errno] $errstr<br />\n"; break; default: echo "Unknown error type: [$errno] $errstr<br />\n"; break; } /* Don't execute PHP internal error handler */ return true; } // function to test the error handling function scale_by_log($vect, $scale) { if (!is_numeric($scale) || $scale <= 0) { trigger_error("log(x) for x <= 0 is undefined, you used: scale = $scale", E_USER_ERROR); } if (!is_array($vect)) { trigger_error("Incorrect input vector, array of values expected", E_USER_WARNING); return null; } $temp = array(); foreach($vect as $pos => $value) { if (!is_numeric($value)) { trigger_error("Value at position $pos is not a number, using 0 (zero)", E_USER_NOTICE); $value = 0; } $temp[$pos] = log($scale) * $value; } return $temp; } // set to the user defined error handler $old_error_handler = set_error_handler("myErrorHandler"); // trigger some errors, first define a mixed array with a non-numeric item echo "vector a\n"; $a = array(2, 3, "foo", 5.5, 43.3, 21.11); print_r($a); // now generate second array echo "----\nvector b - a notice (b = log(PI) * a)\n"; /* Value at position $pos is not a number, using 0 (zero) */ $b = scale_by_log($a, M_PI); print_r($b); // this is trouble, we pass a string instead of an array echo "----\nvector c - a warning\n"; /* Incorrect input vector, array of values expected */ $c = scale_by_log("not array", 2.3); var_dump($c); // NULL // this is a critical error, log of zero or negative number is undefined echo "----\nvector d - fatal error\n"; /* log(x) for x <= 0 is undefined, you used: scale = $scale" */ $d = scale_by_log($a, -2.5); var_dump($d); // Never reached ?> ]]> </programlisting> &example.outputs.similar; <screen> <![CDATA[ vector a Array ( [0] => 2 [1] => 3 [2] => foo [3] => 5.5 [4] => 43.3 [5] => 21.11 ) ---- vector b - a notice (b = log(PI) * a) <b>My NOTICE</b> [1024] Value at position 2 is not a number, using 0 (zero)<br /> Array ( [0] => 2.2894597716988 [1] => 3.4341896575482 [2] => 0 [3] => 6.2960143721717 [4] => 49.566804057279 [5] => 24.165247890281 ) ---- vector c - a warning <b>My WARNING</b> [512] Incorrect input vector, array of values expected<br /> NULL ---- vector d - fatal error <b>My ERROR</b> [256] log(x) for x <= 0 is undefined, you used: scale = -2.5<br /> Fatal error on line 35 in file trigger_error.php, PHP 5.2.1 (FreeBSD)<br /> Aborting...<br /> ]]> </screen> </example> </para> <para> <example> <title>Calling the previous handler from the new one</title> <simpara> The return value of <function>set_error_handler</function> is the handler that was active until then. Calling it from the new handler keeps the existing behaviour while adding to it. This only works if that handler is a user defined function; &null; is returned when the built-in one was active. </simpara> <programlisting role="php"> <![CDATA[ <?php function logging_handler(int $errno, string $errstr): bool { echo "logged: $errstr\n"; return true; } set_error_handler('logging_handler'); $previous = set_error_handler(function (int $errno, string $errstr) use (&$previous): bool { echo "counted: $errstr\n"; return $previous !== null ? $previous($errno, $errstr) : false; }); trigger_error("something happened", E_USER_WARNING); restore_error_handler(); trigger_error("only logged now", E_USER_WARNING); restore_error_handler(); ?> ]]> </programlisting> &example.outputs; <screen> <![CDATA[ counted: something happened logged: something happened logged: only logged now ]]> </screen> </example> </para> </refsect1> <refsect1 role="notes"> &reftitle.notes; <caution> <simpara> Do not revert to the previous handler by passing the return value of <function>set_error_handler</function> back to it. Doing so pushes a further entry onto the stack instead of removing one, so the stack grows without bound in loops and long-running processes, and <parameter>error_levels</parameter> is reset to <constant>E_ALL</constant>, silently widening the range of errors the restored handler receives. <function>restore_error_handler</function> is the intended way to revert to the previous handler. </simpara> </caution> </refsect1> <refsect1 role="seealso"> &reftitle.seealso; <simplelist> <member><exceptionname>ErrorException</exceptionname></member> <member><function>error_reporting</function></member> <member><function>restore_error_handler</function></member> <member><function>get_error_handler</function></member> <member><function>trigger_error</function></member> <member><link linkend="errorfunc.constants">error level constants</link></member> </simplelist> </refsect1> </refentry> <!-- Keep this comment at the end of the file Local variables: mode: sgml sgml-omittag:t sgml-shorttag:t sgml-minimize-attributes:nil sgml-always-quote-attributes:t sgml-indent-step:1 sgml-indent-data:t indent-tabs-mode:nil sgml-parent-document:nil sgml-default-dtd-file:"~/.phpdoc/manual.ced" sgml-exposed-tags:nil sgml-local-catalogs:nil sgml-local-ecat-files:nil End: vim600: syn=xml fen fdm=syntax fdl=2 si vim: et tw=78 syn=sgml vi: ts=1 sw=1 --> |
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