PHP Strings: How to use curly braces to parse objects returned by functions

Question

I have a function that returns an object. How to write a string that parses a member of the object returned by that function (the function is in a different namespace)? This is what I'm trying to do but the string used on echo is invalid.

namespace security;
function &get_user() {
    $user = (object) array('email' => 'abcd@abcd.com', 'name' => 'John Doe');
    return $user;
}

echo "<li><p class=\"navbar-text\">Welcome, {${\security\get_user()}->name}</p></li>";

Sverri M. Olsen · Answer 1 · 2013-09-01T23:56:34.050

3

Well, a few things:

You cannot interpolate functions/method inside strings. Only variables are allowed.
When you create a namespace you only have to refer to it when outside the namespace.
Do not use references (&) unless you understand what they do. In PHP references work differently than in most other languages.

This is how the code will look like.

// We define the namespace here. We do not need
// to refer to it when inside the namespace.
namespace security;

// Objects and arrays are always passed by
// reference, so you should not use & here
function get_user() {
    return (object) array(
        'email' => 'abcd@abcd.com',
        'name' => 'John Doe',
    );
}
// We need to get the value from the function
// before interpolating it in the string
$user = get_user();

// There are a few ways to interpolate in PHP
// This is for historical and functional reasons
// Interpolating array items is, "{$arr['key']}"
echo "<li><p class=\"navbar-text\">Welcome, $user->name</p></li>";
echo "<li><p class=\"navbar-text\">Welcome, {$user->name}</p></li>";

edited Sep 01 '13 at 23:56

answered Sep 01 '13 at 23:45

Sverri M. Olsen

13,055
3
36
52

More precisely, you can use functions/methods inside strings, but they are expected to return a variable name. – Tgr Sep 01 '13 at 23:47
1

It is also possible to use this: `echo "
Welcome, " . get_user()->name . "

ash

Sep 01 '13 at 23:50

Actually the `echo` is inside another php file and namespace. That's why I put namespace. I read the docs and think I understand references and their caveats (http://stackoverflow.com/questions/3307409/php-pass-by-reference-in-foreach) but I still don't understand the implications of returning a reference on the `get_user` function. – Eduardo Sep 02 '13 at 02:25

score 0 · Answer 2 · answered Sep 02 '13 at 00:10

You should not do anything more complex then accessing an object member inside a string; it is hard to read and hard to maintain (e.g. your IDE will probably miss it when doing refactoring). That said, just for the fun of it:

function get_user() {
    $user = (object) array('email' => 'abcd@abcd.com', 'name' => 'John Doe');
    return $user;
}

echo "<li><p class=\"navbar-text\">Welcome, {${($x = \security\get_user()->name) ? 'x' : 'x'}}</p></li>";

The variable assignment is necessary here - you can use functions and just about anything else inside curly braces in a string, but their result will be interpreted as a variable name. Basically, $str = "{${<some code>}}"; is equivalent to $name = eval("<some code>"); $str = $$name;".

PHP Strings: How to use curly braces to parse objects returned by functions

2 Answers2