Retrieving local variables in PHP at runtime?

Question

If I do print_r in $GLOBALS I have all globals vars.

But I need something like this:

function foo() {
   $a = 1;
   $b = 2;
   for($i = 0; $i < 10; $i++);
}

print_r(find_variables_in_function('foo')); // results: array(a => 1, b => 2, i => 10);

I'm trying implement a new feature in code.google.com/p/webgrind/ - since this tool give me functions in run time, I can generate a chart by variables size at end of all functions called.

$x = 2;
$y = 3;

function foo() {
    $a = 1;
    $b = 2;
    for ($i = 0; $i < 10; $i++)
        ;

    print_r(get_defined_vars()); // has no side effects - print null string
}

Why do you **need** this? What's the problem you're trying to solve? — Oliver Charlesworth, Jan 21 '13 at 00:23
It sounds like you have a code structure flaw. You need give us more context. — Austin Brunkhorst, Jan 21 '13 at 00:24
So, you want their values at the point of the last returned call? Remember that several instances of the same variables may exist at the same time. — John Dvorak, Jan 21 '13 at 00:26
Get all variables defined in current scope: http://stackoverflow.com/questions/717852/php-get-all-variables-defined-in-current-scope-symbol-table — Peter Wooster, Jan 21 '13 at 00:27
FYI, one indicator that PHP is not designed to give you this info, is that the Reflection mechanism for functions does not give you variables in the function body: http://php.net/manual/en/class.reflectionfunction.php — DWright, Jan 21 '13 at 00:27
Are you trying to track the memory usage per variable? First, this is not accurate (both may reference the same large object); second, this may differ from call to call. — John Dvorak, Jan 21 '13 at 00:30
Even the status of _what_ variables get defined can change from call to call. — John Dvorak, Jan 21 '13 at 00:32
I only can at this time analyze at end of all functions all variable size and generate a chart by size — Ragen Dazs, Jan 21 '13 at 00:34
Yes I agreed, but just know this size at end will help me a lot of — Ragen Dazs, Jan 21 '13 at 00:36
Then see the linked question, AND it's a different question than your original one (from outside the function). — John Dvorak, Jan 21 '13 at 00:37

Peter Wooster · Accepted Answer · 2013-01-21T01:15:03.720

3

get_defined_vars() returns an array of all the variables defined in the scope in which it was called. If you call that from within the function you will get the variables defined in that function here's the documentation:

http://php.net/manual/en/function.get-defined-vars.php

eg:

<?php 
   function foo() {
       $a = 'first';
       $b = 'second';
       $c = get_defined_vars();
       print "vars=";print_r($c);print"\n";        
   }
   foo();
?>

Here what it prints

$ php testgdvars.php
vars=Array
(
    [a] => first
    [b] => second
)

edited Jan 21 '13 at 01:15

answered Jan 21 '13 at 00:52

Peter Wooster

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Execute the posted example code. get_defined_vars print only variables that in global scope. – Ragen Dazs Jan 21 '13 at 00:55
you need to call it within the function. The variables don't exist outside the function. – Peter Wooster Jan 21 '13 at 00:59
Doesn't exists inside too. As sayed the example code has no side effects – Ragen Dazs Jan 21 '13 at 01:00
1

I added a simple example and its output to the answer. – Peter Wooster Jan 21 '13 at 01:15
I'm not sure of this, but your problem may be calling in the arguments to print_r, that may be viewed as a scope. If there is a language lawyer around they might know the answer to that. – Peter Wooster Jan 21 '13 at 01:18
Yes! I miss a typo in my example. Thanks, this solve my problem. – Ragen Dazs Jan 21 '13 at 01:19

score 0 · Answer 2 · answered Jan 21 '13 at 00:27

0

Outside of the function, the variables aren't defined. Except static variables, and those are private to the function.

Why not just add a var_dump($a,$b,$i); to the end of the function?

answered Jan 21 '13 at 00:27

Niet the Dark Absol

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Question edited to give more context – Ragen Dazs Jan 21 '13 at 00:48

Retrieving local variables in PHP at runtime?

2 Answers2