(PHP 5, PHP 7, PHP 8)
debug_print_backtrace — Mostra um rastreamento retroativo
A função debug_print_backtrace() mostra um rastreamento retroativo do PHP. Ela mostra as chamadas de função, arquivos incluídos por include ou requeridos por require, e resultados de avaliações de eval().
optionsEste parâmetro é uma máscara de bits para as opções a seguir:
| DEBUG_BACKTRACE_IGNORE_ARGS | Omitir os índices de "args", e portanto todos os argumentos de funções/métodos, para economizar memória. |
limit
Este parâmetro pode ser usado para limitar o número de seções de pilha mostradas.
Por padrão (limit=0) ela mostra todas as seções da pilha.
Nenhum valor é retornado.
Exemplo #1 Exemplo de debug_print_backtrace()
<?php
// arquivo include.php
function a() {
b();
}
function b() {
c();
}
function c(){
debug_print_backtrace();
}
a();
?><?php
// arquivo test.php
// este é o arquivo que deve ser executado
include 'include.php';
?>O exemplo acima produzirá algo semelhante a:
#0 c() called at [/tmp/include.php:10] #1 b() called at [/tmp/include.php:6] #2 a() called at [/tmp/include.php:17] #3 include(/tmp/include.php) called at [/tmp/test.php:3]
Another way to manipulate and print a backtrace, without using output buffering:
<?php
// print backtrace, getting rid of repeated absolute path on each file
$e = new Exception();
print_r(str_replace('/path/to/code/', '', $e->getTraceAsString()));
?>I like the output of debug_print_backtrace() but I sometimes want it as a string.
bortuzar's solution to use output buffering is great, but I'd like to factorize that into a function. Doing that however always results in whatever function name I use appearing at the top of the stack which is redundant.
Below is my noddy (simple) solution. If you don't care for renumbering the call stack, omit the second preg_replace().
<?php
function debug_string_backtrace() {
ob_start();
debug_print_backtrace();
$trace = ob_get_contents();
ob_end_clean();
// Remove first item from backtrace as it's this function which
// is redundant.
$trace = preg_replace ('/^#0\s+' . __FUNCTION__ . "[^\n]*\n/", '', $trace, 1);
// Renumber backtrace items.
$trace = preg_replace ('/^#(\d+)/me', '\'#\' . ($1 - 1)', $trace);
return $trace;
}
?>If you see string arguments and parameters getting cut off like this:
#0 hook.php(324): output_notice('checkout_before...')
#1 hook.php(348): invoke_hook('checkout_before...', Array)
You can increase the maximum length of arguments and parameters in the printed trace through an PHP INI setting:
<?php
ini_set('zend.exception_string_param_max_len', 100);
debug_print_backtrace();
?>
…so you can read the full arguments:
#0 hook.php(324): output_notice('checkout_before_payment')
#1 hook.php(348): invoke_hook('checkout_before_payment', Array)
In edge cases, it might even uncover nested traces that you didn't notice before.If your show your error messages in HTML (with suitable safety using entities), this function won't work nicely because it uses newlines for formatting.
Here is a function that works similarly, but using <BR> tags. Insert it near the beginning of your program to add a stack to Warning output only, or modify it as you like:
// Here is code for error stack output in HTML:
function error_handler_callback($errno,$message,$file,$line,$context)
{
if ($errno === E_WARNING)
echo "Stack, innermost first:<br>".nl2br((new Exception())->getTraceAsString());
return false; // to execute the regular error handler
}
set_error_handler("error_handler_callback");