Comment by Crysstalis | Hacker News Reader

Comment by Crysstalis | Hacker News Reader

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>they can be exposed in ways that do not break backwards compatibility and instead applications can opt-in to those features.

This is already how it is. If you want those features, then port to newer versions. If you do not want them, then do not port.

>could have been implemented and designed in such a way as to avoid breaking existing applications but also making porting the applications easy.

This is simply not possible. Many older APIs are just not designed to support this.

>then there is absolutely nothing that is affected in that application by improvement to scaling support, CSS support, rendering models or anything else.

Indeed, such a program would probably be trivial to port.

>With what i describe if Gtk4 was backwards compatible with Gtk1, a binary of that application compiled against Gtk1 would run under Gtk4 and get the new file picker dialog instead of the weird one used in Gtk1, would get antialiased font rendering, would get the themes used by Gtk4, etc.

If you want binary compatibility, that is a different story. It might be possible to get some very trivial GTK1 programs to work with a compatibility layer on top of GTK4. But only the most trivial ones like a form with a couple of buttons. Anything with custom widgets (which is all non-trivial applications) would probably break or would lose most/all of the benefits, the GTK1 API simply was not designed in that way.

> This is already how it is. If you want those features, then port to newer versions. If you do not want them, then do not port.

Sorry but this shows you refuse to understand what i write in my responses.

> This is simply not possible. Many older APIs are just not designed to support this.

Then make new APIs alongside the old APIs.

> Indeed, such a program would probably be trivial to port.

And my point is that it shouldn't need to be ported.

> If you want binary compatibility, that is a different story.

It is not a different story, it is part of the entire backwards compatibility story. I refer to not only binary compatibility but also source compatibility. What i refer to is being able to:

1. Run old binaries in new systems while receiving any new functionality that may apply

2. Compile old programs against the latest version of the library without issues (at least not issues due to the library) and get pretty much the same functionality you'd get if you ran the old binary against the latest version of the library

3. Being able to upgrade the program, in parts or in whole (where that'd make sense - a new approach might be "better" in some ways but not be worth the effort for a particular program so using the old approach should still work)

> It might be possible to get some very trivial GTK1 programs to work with a compatibility layer on top of GTK4.

Such a compatibility is only needed because Gtk4 itself isn't backwards compatible with Gtk1.

I understand exactly what you are saying but it does not make sense. Think of this on the most basic level like with DPI scaling. If an application has no idea of DPI scaling and has a certain DPI hard coded in (like many GTK1 applications do) then you cannot do anything about that with any "backwards compatibility". The application will just not work with DPI scaling until it is ported to work with a variable scale instead of a hard coded DPI. You cannot upgrade the program in parts either, or add a new API alongside it. The whole thing must be changed to support DPI scaling or some of it will be in the incorrect scale and the effects will cascade to other widgets that expect the scale to be passed to them from the parent widget. Because remember everything in a GTK program is in a widget tree that depends on passing down state.

Part of the reason that the themes changed and the CSS implementation got changes was because of these issues, i.e. pretty much all GTK1 and GTK2 applications and themes had no concept of device-independence, most drawing was done hard coding a DPI against raw device pixels. The few applications that implement it themselves would not benefit from any backwards compatibility layer.

You can also apply the same logic to many of the other changes in GTK. Your suggestions just cannot be done by swapping out the library, they are either impossible or are even more impractical than the current situation. If it were as easy as you seem to think it is then the GTK developers would have done it by now.

> Think of this on the most basic level like with DPI scaling. If an application has no idea of DPI scaling and has a certain DPI hard coded in (like many GTK1 applications do) then you cannot do anything about that with any "backwards compatibility".

There are multiple ways to deal with that, for example Lazarus / LCL scales all automatic values by the scale factor. Only when someone deals with pixels directly (e.g. drawing shapes on a canvas manually) has to update the application.

Yes, in that case it wont work automatically, but it can still be good enough for most applications and the changes to make it work "properly" can still be much simpler than doing a massive API upgrade. In a desktop-based bugtracking program i wrote in Lazarus, pretty much all of the UI worked "out of the box" on a GPD Win 1 running KDE/Xorg with scaling set to 150% - except a single widget where i drew things manually. Fixing that was a matter of a few lines of code. Much preferable to having to port to some different toolkit.

Also fallbacks can still be implemented, like using shadow drawing and scaling. These can even be exposed as controls to the user via binary parameters or environment variables, thus allowing users who are not in a position to modify the program (e.g. using some old binary or found some source code that they can compile but do not really have the knowledge to fix themselves) to find a "good enough" scenario. This is why, e.g. Windows have that "Compatibility" tab in there, even if they cannot always get a 100% perfect fix.

The point is at least making an effort.

> they are impossible.

They are not impossible, most of the time when a programmer claims something is "impossible" they haven't tried or thought enough or tried to think enough out of the box: you have to take that into account from the point where you design the new features, not try to backport them after the fact.

A bunch of Gtk4 features as it exists and was designed right now with the current mindset will certainly feel hard / impossible to backport to something like Gtk1. The point is not have that mindset in the first place and treat backwards compatibility as a feature as important as anything else at all points during the development of the library.

>Only when someone deals with pixels directly (e.g. drawing shapes on a canvas manually) has to update the application.

Pretty much every custom widget with custom drawing does this, so that excludes most non-trivial applications from using this method.

>Much preferable to having to port to some different toolkit.

Again, for applications with no custom widgets or without any use of the complex features, the porting effort to newer versions of GTK is also just a few lines of code, if even that. The simple things like buttons and inputs have barely changed.

>The point is at least making an effort.

Well, GNOME will probably not make this effort, as they dropped GTK1 around twenty years ago. It is not used anywhere in their stack. It was much easier and more beneficial for them to port or rewrite every application, multiple times actually. So I cannot really buy this complaint that porting is so difficult yet adding this compatibility to GTK1 is supposedly easy. If the method in Lazarus works so well then maybe an interested party should look at implementing it into GTK1 proper, because no one else seems to have any interest in maintaining GTK1.

>you have to take that into account from the point where you design the new features, not try to backport them after the fact.

Again there is nothing to take into account here. The issue is that the app developers also have hard coded these bad assumptions into their apps. If the app has to be changed to change the assumption then you might as well just port the app, because the only way to deal with it is to do that or backport it after the fact.

> Pretty much every custom widget with custom drawing does this, so that excludes most non-trivial applications from using this method.

A large part of even non-trivial applications do not do custom drawing - and many do not do any custom drawing at all. In the cases where this is needed, you only need to fix the particular drawing code and nothing else.

> the porting effort to newer versions of GTK is also just a few lines of code, if even that

Even if that is the case, it still has all the other backwards compatibility issues i mentioned.

> Well, GNOME will probably not make this effort, as they dropped GTK1 around twenty years ago.

The effort i mentioned here was on designing backwards compatible APIs and libraries, not about supporting something specific to Gtk1. I do not expect GNOME / Gtk developers to support Gtk3 for long, let alone Gtk1.

> Again there is nothing to take into account here.

The "that" in "have to take that into account" was backwards compatibility, not DPI scaling.

Look, we're going in circles and i do not feel like having to explain things that i believe should be self-explanatory all the time. So there is no really any point continuing that discussion, it is not like i expect any Gtk developer to suddenly come across my posts and somehow get enlightened or something and Gtk stops breaking itself (and well, even if one does, they'd have a hard time convincing the other developers, so it is probably better for their psyche if they do not understand what i write :-P).

>A large part of even non-trivial applications do not do custom drawing - and many do not do any custom drawing at all.

Then those parts will be easier to port as well, so there is not much benefit to having this backwards compatibility when more benefits can be gained by porting. This is why most GNOME applications have ported.

>Even if that is the case, it still has all the other backwards compatibility issues i mentioned.

Those issues would be even worse by trying to hack various things into GTK1.

>The effort i mentioned here was on designing backwards compatible APIs and libraries

My point was that some things are impossible to design in a backwards compatible way. For example, anything that leads to certain assumptions getting hard coded in the app. You cannot API design your way out of those type of problems. The app has to be rewritten or ported.

>it is not like i expect any Gtk developer to suddenly come across my posts and somehow get enlightened or something

Keep in mind that GTK developers have very likely already weighed the benefits of what you are suggesting and have decided that it is not worth it, for various reasons.

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