Basic Use

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Overview

traceArguments() is used to trace the function arguments. There is no need to pass the function arguments to traceArguments() to trace them. Note that traceArguments() may not be used, if the function does not call any other function or if the function calls functions that are not being traced.

traceVariables() is used to trace variables within the function. The variables to trace must be passed as arguments to traceVariables(). traceVariables() may be called as many times as required to watch variables value change.

traceReturn() is used to trace the variables returned by the function. The variables to trace must be passed as arguments to traceReturn().

putTrace() is used to display the trace to the standard output or to write it into a file.

How to use PHP_FunctionCallTracer

In this example, package.php contains two classes whose methods are traced. The package is used by an application trace.php. The trace is stored into trace.txt. To generate the trace, run: #php trace.php.

Example 58-1. The package package.php

Note that testing if PHP_FunctionCallTracer is loaded: class_exists('PHP_FunctionCallTracer', false), is optional. It is useful only if the tracing methods are meant to be left in the code. They will be called only if PHP_FunctionCallTracer is loaded.

class math {
    /**
     * tracing the arguments and the returned parameter
     *
     * note that traceReturn() calls traceArguments() by default which is fine here
     * since this method does call other methods to trace
     */
    public static function prod($x, $y)
    {
        // class_exists('PHP_FunctionCallTracer', false)
        // and PHP_FunctionCallTracer::traceArguments();
        $p = $x * $y;

        class_exists('PHP_FunctionCallTracer', false) and
        PHP_FunctionCallTracer::traceReturn($p);
        return $p;
    }

    /**
     * tracing the arguments and the returned parameter
     *
     * traceArguments() must be called here since this method calls other methods
     * that may be traced, so that traced calls are displayed in the right order
     */
    public static function square($x)
    {
        class_exists('PHP_FunctionCallTracer', false) and
        PHP_FunctionCallTracer::traceArguments();

        $x2 = self::prod($x, $x);

        class_exists('PHP_FunctionCallTracer', false) and
        PHP_FunctionCallTracer::traceReturn($x2);
        return $x2;
    }
}

class geometry {
    private $pi = 3.14;

    /**
     * tracing the arguments and the returned parameter
     * another variable is traced along with the returned parameter
     */
    public function circle($r)
    {
        class_exists('PHP_FunctionCallTracer', false) and
        PHP_FunctionCallTracer::traceArguments();

        $pi2 = 2 * $this->pi;
        $c = math::prod($r, $pi2);

        class_exists('PHP_FunctionCallTracer', false) and
        PHP_FunctionCallTracer::traceReturn($c, $pi2);
        return $c;
    }

    /**
     * tracing the arguments, some variables and the returned parameter
     */
    public function disk($r)
    {
        class_exists('PHP_FunctionCallTracer', false) and
        PHP_FunctionCallTracer::traceArguments();

        $r2 = math::square($r);
        class_exists('PHP_FunctionCallTracer', false) and
        PHP_FunctionCallTracer::traceVariables($r2, $this->pi);

        $d = math::prod($r2, $this->pi);

        class_exists('PHP_FunctionCallTracer', false) and
        PHP_FunctionCallTracer::traceReturn($d);
        return $d;
    }
}

Example 58-2. The application trace.php

/**
 * adds the path of the package if this is a raw install
 * includes the package (example) to debug and the tracer package
 */
file_exists("../../../../PHP/") and set_include_path('../../../..' . PATH_SEPARATOR . get_include_path());
require_once 'package.php';
require_once 'PHP/FunctionCallTracer.php';

/**
 * creates an instance of the class to debug and calls a few methods
 * writes the trace in a file
 */
$geometry = new geometry;
$c = $geometry->circle(2);
$d = $geometry->disk(3);

$file = dirname(__FILE__) . '/trace.txt';
PHP_FunctionCallTracer::putTrace($file, false);

Example 58-3. The trace trace.txt

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