In the modern (all iOS and 64-bit macOS) runtime the ivar offsets are patched up at runtime so the layout of classes (including base classes) can change without breaking compatibility.
Working around the limitations of the 32-bit Objective-C runtime imposes significant costs, it is far from a simple recompile with a different pointer size. It also adds a lot to the size of the installed OS.
In a way, this is the true last step of the Mac OS X transition that started in 2001--the removal of the transitional APIs that made it possible.
Theoretically would’nt programms written in pure Swift today be able to compile for any new hardware plateform, thus avoiding the kind of issues that 32/64 switch faced?
The educational story of this sort is the transition between python 2 and 3... not ever done for some packages.
If you want to find unusual problems with older Apple hardware for the sake of reusability, take a look at the firmware from around that time. It was just weird enough to make it similar to standards but often too difficult to support a decade later. In a decade, people are going to say the same about the not-quite NVMe SSD interfaces in current Macs.
Anyhow, I doubt they'd have had time to make a solid 64bit x86_64 SDK even if they had delayed the hardware to late 2006. They had never stopped maintaining the x86 port of OS X (aka Rhapsody, Open Step, NeXT Step), just stopped shipping it as a product, because their strategy was and still is to package their OS in hardware boxes. They started shipping x86 boxes to developers in the form of the x86 development box, which was a (32bit) Pentium 4 shoehorned into a Power Mac G5 case. Its OS is also what leaked to the early x86 hackintosh scene; before Apple shipped their own x86 Macs. I ran it on an custom Athlon64 box and a ThinkPad T42.
Since they already had the x86 port, it was an easy switch at a time when all x86 hardware from Intel was still 32bit. If they knew Intel would adopt x86_64 from AMD, one option could've been to ship with AMD CPU's on the first models, but I'm not sure how well that'd have turned out logistically or whether it'd have made a huge difference.
We have 20000 Mac users in a company of 90000, I don’t think this is a corner case for large technology companies.
My machine is managed in the sense some things are preinstalled and IT has a way to push software updates.
What more management is required? Anything more and IT would probably fuck it up like they did when our division was still on Windows.
Not saying your company has to be like this. Just saying 1) this is where MS has very little competition, and 2) where they make absolute bank.
Company size doesn't have much to do with this. Macs are popular at IBM.
140,000+ employees in this company. Macs outnumbers Windows boxes. Pretty much the only place you see Windows machines are in the various accounting departments, and in the call centers where they're just used as terminals to big iron.
At least as one gets older and just want to get that thing done that they always have (a certain big name author still writes using WordStar in DOS i believe).
Do they really, or is it just that consumers are more likely to be persuaded by Apple's marketing?
Personally, I have some apps which I use regularly, and are at least 20 years old. I use mostly Windows for that reason too.
My Ubuntu netbook is nice for travelling purposes, but for the kind of work I get paid for, it is Windows and occasionally macOS.