What changes in code are required to make Joomla 3.5 extensions PHP7 compatible?

Question

(Please bear with me, I am sorry but I just can't ask this quickly.)

We are all hardly waiting for Stable Version of Joomla 3.5.0, aren't we?

RC3 RC4 was released today and it is just a matter of days until she gets finaly released (Joomla 3.5.0 Stable was just released on Monday, March 21st 2016), after more than a year in making and numerous goals changes and ETA postponements.

The biggest feature, among all other noticeable improvements, definitely will be ability to run on newest PHP7, resulting in almost 50% faster execution and almost 4 times decrease in memory consumption (source).

Due to inner changes in PHP7 (the introduction of type hints and the now-reserved words “int”, “string” and “float”) it will result in Backwards Compatibility Break for numerous extensions, even though Joomla 3.5.0 core itself will be fully compatible with PHP7.
(source: Backwards Compatibility break from RC4 Release News:)

We have a backwards compatibility promise to make sure code doesn’t suddenly break. However there are circumstances that can force us to no longer keep this promise. In Joomla 3.5 this is the case. Due to changes in PHP 7, we had to rename the String class to StringHelper otherwise Joomla! cannot run on PHP 7. This is a very minor change and we don’t expect any issues from it. For those interested, you can read more about it at Update to String package 1.3.

I have been keenly following her development and tested J!3.5.0 on SiteGround's PHP7 since her first Betas until newest RC4, and I can confirm improvements are noticable and great.

BUT... Right now I am very concerned How Fast will we see all extensions fully updated to support PHP7? There is a big chance that it will take months until we will be able to freely run our sites on new PHP configured as they are now on v3.4.8.

SO... I am seriously considering manualy updating some of my favorite admin extensions to support PHP7, so I can continue using them on new v3.5. For those which are popular and actively supported (like Akeeba, JCE, etc...) I will wait for developer's updates hoping they will come pretty fast. But for those which are not being actively supported anymore (there are many of them which I keep using for ages, just don't ask me for details, please) I will have to update them by myself.

AND... My question finally is: Do you happen to know which changes in code are required in order to make some extension PHP7 compatible?
I mean, besides changes which Joomla team itself had to undergo for Update to String package 1.3...

Answer 1

Ok first thing's first. Joomla 3.5.0 stable will be released tomorrow next monday :)

I take a step back and firstly take a backup of your site and install it on a subdomain or your localhost, running PHP 7.0.4.

Once done, thoroughly test it.

As for the extensions, I Nicolas from Akeeba already supports PHP 7 and other popular extensions will most likely already support it.

I would refrain from making any core changes yourself and wait for the developer to update as and when they can. You know the "core hack" drill....it's a "no go" area.

As for backward incompatibility changes, have a look at the following from the official PHP website:

http://php.net/manual/en/migration70.incompatible.php

Overall, maybe wait a couple of months till PHP 7 is a little more stable. It's still relatively new and there will definitely be some biggish bugs out there.

Hope this helps

Answer 2

This is NOT an answer to my question, I just wanted to share a link which I just found and which might be helpful in upgrading our Joomlas to 3.5:

There is a Google Doc "List of Joomla! Extensions Supporting Joomla! 3.5 and PHP 7", which is publicly available and maintained by community (we are talking about Joomla, after all :-) ).

I know I should have put it as comment and not as answer, but I think its more visible this way.