Object-oriented design patterns in C and kernel development
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Re: Object-oriented design patterns in C and kernel development
#2> The article describes how the Linux kernel, despite being written in C, embraces object-oriented principles by using function pointers in structures to achieve polymorphism.
This technique predates object oriented programming. It is called an abstract data type or data abstraction. A key difference between data abstraction and object oriented programming is that you can leave functions unimplemented in your abstract data type while OOP requires that the functions always be implemented.
The sanest way to have optional functions in object oriented programming that occurs to me would be to have an additional class for each optional function and inherit each one you implement alongside your base class via multiple inheritance. Then you would need to check at runtime whether the object is an instance of the additional class before using an optional function. With an abstract data type, you would just be do a simple NULL check to see if the function pointer is present before using it.
Re: Object-oriented design patterns in C and kernel development
#3> The article describes how the Linux kernel, despite being written in C, embraces object-oriented principles by using function pointers in structures to achieve polymorphism. This technique predates object oriented programming. It is called an abstract data type or data abstraction. A key difference between data abstraction and object oriented programming is that you can leave functions unimplemented in your abstrac…
I largely agree, and use these patterns in C, but you’re neglecting the usual approach of having a default or stub implementation in the base for classic OOP. There’s also the option of using interfaces in more modern OOP or concept-style languages where you can cast to an interface type to only require the subset of the API you actually need to call. Go is a good example of this, in fact doing the lookup at runtime from effectively a table of function pointers like this.
Re: Object-oriented design patterns in C and kernel development
#4> Having to pass the object explicitly every time feels clunky, especially compared to C++ where this is implicit.
I personally don't like implicit this. You are very much passing a this instance around, as opposed to a class method. Also explicit this eliminates the problem, that you don't know if the variable is an instance variable or a global/from somewhere else.
Re: Object-oriented design patterns in C and kernel development
#5> The article describes how the Linux kernel, despite being written in C, embraces object-oriented principles by using function pointers in structures to achieve polymorphism. This technique predates object oriented programming. It is called an abstract data type or data abstraction. A key difference between data abstraction and object oriented programming is that you can leave functions unimplemented in your abstrac…
The concept of abstract data type is a real idea in the days of compiler design. You might as well say "compiler design predates object oriented programming". The technique described in the lead is used to implement object-oriented programming structures, just as it says. So are lots of compiler design features under the hood.
source- I wrote a windowing framework for MacOS using this pattern and others, in C with MetroWerks at the time.
Re: Object-oriented design patterns in C and kernel development
#6> The article describes how the Linux kernel, despite being written in C, embraces object-oriented principles by using function pointers in structures to achieve polymorphism. This technique predates object oriented programming. It is called an abstract data type or data abstraction. A key difference between data abstraction and object oriented programming is that you can leave functions unimplemented in your abstrac…
In Smalltalk and Objective-C, you just check at runtime whether an object instance responds to a message. This is the original OOP way.
It's sad that OOP was corrupted by the excessively class-centric C++ and Java design patterns.
Re: Object-oriented design patterns in C and kernel development
#7> The article describes how the Linux kernel, despite being written in C, embraces object-oriented principles by using function pointers in structures to achieve polymorphism. This technique predates object oriented programming. It is called an abstract data type or data abstraction. A key difference between data abstraction and object oriented programming is that you can leave functions unimplemented in your abstrac…
In Smalltalk and Objective-C, you just check at runtime whether an object instance responds to a message. This is the original OOP way. It's sad that OOP was corrupted by the excessively class-centric C++ and Java design patterns.
Wait, so in obj-c, could you also write some kijdnof doesnotunderstand method to achieve some dynamic method dispatch?
Re: Object-oriented design patterns in C and kernel development
#8> The article describes how the Linux kernel, despite being written in C, embraces object-oriented principles by using function pointers in structures to achieve polymorphism. This technique predates object oriented programming. It is called an abstract data type or data abstraction. A key difference between data abstraction and object oriented programming is that you can leave functions unimplemented in your abstrac…
In Smalltalk and Objective-C, you just check at runtime whether an object instance responds to a message. This is the original OOP way. It's sad that OOP was corrupted by the excessively class-centric C++ and Java design patterns.
Actually I would say that it is sad that developers learn a specific way how a technology is done in language XYZ and then use it as template everywhere else, what happened to the curiosity of learning?
Re: Object-oriented design patterns in C and kernel development
#9> The article describes how the Linux kernel, despite being written in C, embraces object-oriented principles by using function pointers in structures to achieve polymorphism. This technique predates object oriented programming. It is called an abstract data type or data abstraction. A key difference between data abstraction and object oriented programming is that you can leave functions unimplemented in your abstrac…
The concept of abstract data type is a real idea in the days of compiler design. You might as well say "compiler design predates object oriented programming". The technique described in the lead is used to implement object-oriented programming structures, just as it says. So are lots of compiler design features under the hood. source- I wrote a windowing framework for MacOS using this pattern and others, in C with Me…
Compiler design does predate object oriented programming. The first compiler was made by John Backus et al at IBM in April 1957.
As for abstract data types, they originated in Lisp, which also predates object oriented programming.
Re: Object-oriented design patterns in C and kernel development
#10Earlier quoted context omitted.
In Smalltalk and Objective-C, you just check at runtime whether an object instance responds to a message. This is the original OOP way. It's sad that OOP was corrupted by the excessively class-centric C++ and Java design patterns.
Wait, so in obj-c, could you also write some kijdnof doesnotunderstand method to achieve some dynamic method dispatch?
Yes, that is how microservices were implemented in the days of NeXTSTEP. with PDO.