Are PHP short tags acceptable to use?

There must be a clear distinction between the PHP short tag (<?) and shorthand echo tag (<?=)

The former is prohibited by the PHP Coding standard, mostly out of common sense because it's a PITA if you ever have to move your code to a server where it's not supported (and you can't enable it). As you say, lots of shared hosts do support shorttags but "lots" isn't all of them. If you want to share your scripts, it's best to use the full syntax.

Whereas the shorthand echo tag <?= cannot be disabled and therefore is fully acceptable to use.

I agree that <? is easier on programmers than <?php but it is possible to do a bulk find-and-replace as long as you use the same form each time.

I don't buy readability as a reason at all. Most serious developers have the option of syntax highlighting available to them.

As ThiefMaster mentions in the comments, as of PHP 5.4, <?= ... ?> tags are supported everywhere, regardless of shorttags settings. This should mean they're safe to use in portable code but that does mean there's then a dependency on PHP 5.4+. If you want to support pre-5.4 and can't guarantee shorttags, you'll still need to use <?php echo ... ?>.

Also, you need to know that ASP tags <% , %> , <%= , and script tag are removed from PHP 7. So if you would like to support long-term portable code and would like switching to the most modern tools consider changing that parts of code.

I'm too fond of <?=$whatever?> to let it go. Never had a problem with it. I'll wait until it bites me in the ass. In all seriousness, 85% of (my) clients have access to php.ini in the rare occasion they are turned off. The other 15% use mainstream hosting providers, and virtually all of them have them enabled. I love 'em.

Starting with PHP 5.4, the echo shortcut is a separate issue from short tags, as the echo shortcut will always be enabled. It's a fact now:

• SVN Revision by Rasmus Lerdorf
• Mailing list discussion

So the echo shortcut itself (<?=) is safe to use now.