Too Far Afield » php

Type Hinting in PHP

Patrick — Sat, 05 Sep 2009 03:26:21 +0000

PHP 5 introduces Type Hinting. But it does so in the usual PHP way: It’s neither fish nor fowl. You’ll be exited at first when you discover the new feature. And then you’ll be disappointed. Because things do not work like you’d expect. Suppose you do something like this:


 
function foo ( string $bar) {
   echo $bar;
}
foo ('Hello World!');
 
?>


What happens, when you execute the above code? You will get a rather cryptic error message:

Catchable fatal error: Argument 1 passed to foo() must be an instance of string, string given.

So the method expected a string as the first parameter and you passed a string to it, but PHP chose to throw up regardless. Great, isn’t it? Of course, the reason for this is right at the very bottom of the PHP documentation on Type Hinting. All the way down the page below a number of examples:
Type Hints can only be of the object and array  (since PHP 5.1) type. Traditional type hinting with int and string isn’t supported.
Doh!

Storing binary data inside a MySQL database

Patrick — Tue, 28 Apr 2009 05:52:33 +0000

Sometimes you need to store binary data inside a MySQL database. While there are various field types for binary data in MySQL, its handling of binary data has a share of different problems. As far as I know you might hit some bugs, if you’re using non-standard connection encodings or character sets. Also, binary data is a hell to escape properly. For example, if you store S????'x7?ma?X?UHMh? inside the MySQL database you might end up with ?????r??v ???????v later under certain conditions. This is not really ideal, to say the least.

The best thing to do is to convert the binary data to a string-based representation, e.g. a hexadecimal form or use a two-way encryption method like Base64. In fact, I recommend to use Base64. The drawback is, that a Base64 representation uses around 35% more space than the original binary representation. For example, in PHP you would do something like this:

// Encode binary data
$binary = base64_encode($binary);
// Decode binary data
$binary = base64_decode($binary);

Update: Changed the example data slightly to accommodate some screen readers, that require a valid feed. Thank you Jan for pointing this out.