Page 1 of 1
[wish] Wish to support multi base
Posted: 01 Apr 2021, 03:23
by QiuDao
Wish to support multi base in objects using the depth-first algorithm like the multiple inheritance in python which uses the breadth First Search though.
Re: Preview of changes: scope, function and variable references
Posted: 08 Apr 2021, 01:21
by QiuDao
In my opinion, the base mechanism for object is a most convenient language feature in AHK's OOP which does exceed some OOP language like python, c++, C#, etc, except that it only supports a single base in AHK's objects.
Is there a reason that every object should have only one base? How about implementing multiple bases in objects just like the multiple inheritance in python but using the depth-first algorithm instead which I think is more intuitive and suitable for AHK's base mechanism. One benefit is that it can reduce the length of the object's base chain and some objects have no need to inherit some base sometimes just to make up the base chain. It will become more flexible.
I don't think there are some side effects to introduce the multiple base for objects. You even need not have any modifications to the built-in class, just keep the way they are which has only one base, and the multi-base usage remains for our users.
Need not say the diamond inheritance, we can just avoid it in code writing, can't we?-
Re: [wish] Wish to support multi base
Posted: 08 Apr 2021, 02:48
by lexikos
@QiuDao I have moved your post here as it appeared to be completely unrelated to the
original topic.
I personally don't see any value in implementing multiple inheritance, and that's reason enough; but I can come up with a few others:
1. Simplicity (of implementation, documentation, usage).
2. Performance.
3. Memory usage.
Perhaps memory usage could be preserved by optimizing for single-inheritance, but not without sacrificing more performance or simplicity. Optimizing all of these requires time that I won't spend.
Another reason is that objects already have the flexibility to implement the behaviour of multiple inheritance in script.
Re: [wish] Wish to support multi base
Posted: 28 May 2021, 23:56
by Helgef
I agree with @QiuDao. Versus implementing this _in script_, I think having it built-in have favours scripts as follows,
1. Simplicity (implementation, readability)
2. Performance
Cheers.
Re: [wish] Wish to support multi base
Posted: 29 May 2021, 01:19
by SOTE
Multiple inheritance is quite controversial, even in deeply OOP circles. Exemplified by the famous "diamond problem" (causing havoc as to which method a child class inherits from multiple parents). Various programming languages don't allow it, so are only single inheritance. Of those that allow for multiple inheritance, they have to implement all kinds of strategies to prevent problems.
What exactly are people doing in a scripting language such as AutoHotkey, where they think such is a necessity? This arguably wouldn't be a user friendly feature, but something that's more hard core. I'm curious as to the use case. How are some such advocates getting stuck, where multiple inheritance is seen as the only salvation? Or, is this something that is thought to be good to have, because some other language has it?
Re: [wish] Wish to support multi base
Posted: 05 Jun 2021, 04:41
by V2User
SOTE wrote: ↑29 May 2021, 01:19
How are some such advocates getting stuck, where multiple inheritance is seen as the only salvation? Or, is this something that is thought to be good to have, because some other language has it?
@lexikos
For example, an object named
objC inherits two bases. One is
baseB, the other is
baseA whose base is
baseB. If you want to reset
baseB to another baseObj for
objC and at the same time avoid
baseA taking place any changes, multiple base is the only solution. No alternatives at this time if without reconstruction I think.
Re: [wish] Wish to support multi base
Posted: 05 Jun 2021, 05:15
by lexikos
@V2User I have no idea what point you are trying to make. Your object starts with already having multiple bases, then you (poorly) describe an abstract problem lacking any practical details, and pose multiple bases as the solution. If there is no multiple inheritance in the first place, it seems the problem you posed can't possibly occur, so it seems that multiple inheritance is the cause of the problem, not the solution.
I'm pretty sure you answered neither of SOTE's questions.
Re: [wish] Wish to support multi base
Posted: 05 Jun 2021, 06:03
by V2User
lexikos wrote: ↑05 Jun 2021, 05:15
@V2User I have no idea what point you are trying to make. Your object starts with already having multiple bases, then you (poorly) describe an abstract problem lacking any practical details, and pose multiple bases as the solution. If there is no multiple inheritance in the first place, it seems the problem you posed can't possibly occur, so it seems that multiple inheritance is the cause of the problem, not the solution.
I'm pretty sure you answered neither of SOTE's questions.
@lexikos
I am sorry I didn't describe it correctly in my above reply. Here is the correct version:
Code: Select all
baseB:={}
baseA:={base:baseB}
objC:={base:baseA}
For example, an object is named
objC in whose base chain contains two bases.That is:
objC's base is
baseA while
baseA's base is
baseB.
If you want to reset
baseB(It currently means
baseA's base as it has not multiple base yet) to another baseObj for
objC and at the same time avoid
baseA occurring any changes, then, multiple base is the only solution. There are no alternatives at this time if without a code reconstruction I think.
However, with multiple base support, we can write:
Code: Select all
baseB:={}
baseA:={}
objC:={base:baseA,base[2]:baseB}
It is probably the only solution.
There is no doubt that it is the most elegant and efficient at the same time.
Re: [wish] Wish to support multi base
Posted: 11 Jun 2021, 19:55
by lexikos
I'll echo this:
SOTE wrote: How are some such advocates getting stuck, where multiple inheritance is seen as the only salvation?
I wrote:objects already have the flexibility to implement the behaviour of multiple inheritance in script.
So no, it is not definitely not the only solution.
Composition is not only a valid alternative to
multiple inheritance, but is said to have advantages. If you want to know more, there are numerous blog articles and Q&A posts about composition vs. inheritance in other languages.
In fact, composition by collecting properties together in one base object generally performs better than dynamic inheritance. I have used it as a means of optimization with chained single inheritance, but it could be easily used to implement a form of multiple inheritance.
Re: [wish] Wish to support multi base
Posted: 15 Jun 2021, 23:38
by SOTE
lexikos wrote: ↑11 Jun 2021, 19:55
SOTE wrote: How are some such advocates getting stuck, where multiple inheritance is seen as the only salvation?
I wrote:objects already have the flexibility to implement the behaviour of multiple inheritance in script.
lexikos wrote:
So no, it is not definitely not the only solution.
Composition is not only a valid alternative to multiple inheritance, but is said to have advantages. If you want to know more, there are numerous blog articles and Q&A posts about composition vs. inheritance in other languages.
In fact, composition by collecting properties together in one base object generally performs better than dynamic inheritance. I have used it as a means of optimization with chained single inheritance, but it could be easily used to implement a form of multiple inheritance.
Excellent answer.