SOLID principals in D
Hi, I come from a C# background and have been looking at D. How well does D implement solid principals? I've grown to really enjoy the SOLID style. For those unfamiliar, SOLID is an acronym for: - Single purpose: Meaning every unit of code (whether it's a function or class) should only have one reason to change. - Open/Close principal: Things should be open to extension but closed to modification. The example I like to use is some sort of IConverter object. Things can implement IConverter, but if you need a new way to 'convert' things, you don't extend an existing object, but instead create a new class that implements IConverter. - Liskov substitution principle: Essentially says if I have a method/function that takes a base class, then the behavior of that method shouldn't change when passing in derived objects. I think the term people like to use is whether or not you use a base/derived class it shouldn't effect the 'correctness' of the program. - Interface segregation principal: Essentially breaking the program up into smaller interfaces. Sometimes only consistent of one or two methods/properties (can feed into 'S' of SOLID quite nicely). - Dependency inversion principle: Things should depend on abstractions not concretions. Strongly enables dependency injection. D seems to have all of the features *required* to make this happen, but I guess the real question is the last two, and more specifically the last one.
Re: SOLID principals in D
On Saturday, 16 June 2018 at 19:20:30 UTC, FromAnotherPlanet wrote: Hi, I come from a C# background and have been looking at D. How well does D implement solid principals? I've grown to really enjoy the SOLID style. For those unfamiliar, SOLID is an acronym for: - Single purpose: Meaning every unit of code (whether it's a function or class) should only have one reason to change. - Open/Close principal: Things should be open to extension but closed to modification. The example I like to use is some sort of IConverter object. Things can implement IConverter, but if you need a new way to 'convert' things, you don't extend an existing object, but instead create a new class that implements IConverter. - Liskov substitution principle: Essentially says if I have a method/function that takes a base class, then the behavior of that method shouldn't change when passing in derived objects. I think the term people like to use is whether or not you use a base/derived class it shouldn't effect the 'correctness' of the program. Also if there is any good literature that explains the 'D' way of going about these principals or even how it enhances them that would be helpful. - Interface segregation principal: Essentially breaking the program up into smaller interfaces. Sometimes only consistent of one or two methods/properties (can feed into 'S' of SOLID quite nicely). - Dependency inversion principle: Things should depend on abstractions not concretions. Strongly enables dependency injection. D seems to have all of the features *required* to make this happen, but I guess the real question is the last two, and more specifically the last one.
Re: SOLID principals in D
On Saturday, 16 June 2018 at 19:20:30 UTC, FromAnotherPlanet wrote: Hi, I come from a C# background and have been looking at D. How well does D implement solid principals? I've grown to really enjoy the SOLID style. For those unfamiliar, SOLID is an acronym for: - Single purpose: Meaning every unit of code (whether it's a function or class) should only have one reason to change. - Open/Close principal: Things should be open to extension but closed to modification. The example I like to use is some sort of IConverter object. Things can implement IConverter, but if you need a new way to 'convert' things, you don't extend an existing object, but instead create a new class that implements IConverter. - Liskov substitution principle: Essentially says if I have a method/function that takes a base class, then the behavior of that method shouldn't change when passing in derived objects. I think the term people like to use is whether or not you use a base/derived class it shouldn't effect the 'correctness' of the program. - Interface segregation principal: Essentially breaking the program up into smaller interfaces. Sometimes only consistent of one or two methods/properties (can feed into 'S' of SOLID quite nicely). - Dependency inversion principle: Things should depend on abstractions not concretions. Strongly enables dependency injection. D seems to have all of the features *required* to make this happen, but I guess the real question is the last two, and more specifically the last one. I am still not a D pro, so some thoughts maybe a bit off... (intro part) The "true D" guru's would tell you "in D your typical code would be mostly ranges(or templates) instead of classes", there is a good portion truth, but IMHO I find it overly attached. D uses duck typing for ranges, which means for example very basic (input) range have this protocol of 3 primitives - popFront(), front, empty Ranges heavily used in conjunction with templates, and templates is static thing, but with clever use of duck typing and that range protocol usually you don't care about specific type at all when dealing with ranges. Of course there is polymorphic interface(as in C#) for ranges too. Now how it applies to S and O? Ranges is basically an essence of S principle, they do exactly single thing, and most functions taking ranges as well. Just look at this "Sort lines" or some other examples on main page: - stdin .byLineCopy .array .sort!((a, b) => a > b) // descending order .each!writeln; -- stdin is console input stream, what happens next? all four functions above operates on ranges, and you can clearly tell what is their purpose. In this simple example they started operate on stdin, but in no way limited to it. It can be file, network stream or whatever else as long it is implements range protocol. Even though these functions may have different interface this is still the possibility for open/close principle. (yep, I agree this isn't the best example) (sorry, this part is not about SOLID at all) This is how most of standard library built, sure this isn't C# BCL and there is so very few things comparing to it, and there is very few use of polymorthic types in it, but it is highly generic because of use of templates. But enough about standard library, you are not forced to do everything that way, there is of course classes and interfaces, they work same as in C#, mostly. In own code you can do pretty much anything you can in C# (not actually sure what you can't) using classes and interfaces. I skip the Liskov principle. Classes and interfaces is enough to cover it, but again D is not limited to them, so you may even find your own discoveries. A word about DI in both D and D in SOLID: This isn't actually limited to just classes, basically it means that you(client code) provide dependencies(whatever things needed to be operational) for function/class you use to do the work, so they don't just 'new' it on their own. There is even a DI framework[1] (don't mind the names in API, I think it is heavily inspired by Java's Spring) Since you are coming from C# background the current state of tooling may shock you, the standard library is not a swiss knife and doesn't have all the goodies BCL has, I even pointed out there is not that much OOP stuff and polymorphism in it. There is also some language design choices that may surprise(both good and not so good ways) you. [1] https://code.dlang.org/packages/aedi
Re: SOLID principals in D
On Sunday, 17 June 2018 at 01:38:17 UTC, evilrat wrote: On Saturday, 16 June 2018 at 19:20:30 UTC, FromAnotherPlanet wrote: Hi, I come from a C# background and have been looking at D. How well does D implement solid principals? I've grown to really enjoy the SOLID style. For those unfamiliar, SOLID is an acronym for: - Single purpose: Meaning every unit of code (whether it's a function or class) should only have one reason to change. - Open/Close principal: Things should be open to extension but closed to modification. The example I like to use is some sort of IConverter object. Things can implement IConverter, but if you need a new way to 'convert' things, you don't extend an existing object, but instead create a new class that implements IConverter. - Liskov substitution principle: Essentially says if I have a method/function that takes a base class, then the behavior of that method shouldn't change when passing in derived objects. I think the term people like to use is whether or not you use a base/derived class it shouldn't effect the 'correctness' of the program. - Interface segregation principal: Essentially breaking the program up into smaller interfaces. Sometimes only consistent of one or two methods/properties (can feed into 'S' of SOLID quite nicely). - Dependency inversion principle: Things should depend on abstractions not concretions. Strongly enables dependency injection. D seems to have all of the features *required* to make this happen, but I guess the real question is the last two, and more specifically the last one. I am still not a D pro, so some thoughts maybe a bit off... (intro part) The "true D" guru's would tell you "in D your typical code would be mostly ranges(or templates) instead of classes", there is a good portion truth, but IMHO I find it overly attached. D uses duck typing for ranges, which means for example very basic (input) range have this protocol of 3 primitives - popFront(), front, empty Ranges heavily used in conjunction with templates, and templates is static thing, but with clever use of duck typing and that range protocol usually you don't care about specific type at all when dealing with ranges. Of course there is polymorphic interface(as in C#) for ranges too. Now how it applies to S and O? Ranges is basically an essence of S principle, they do exactly single thing, and most functions taking ranges as well. Just look at this "Sort lines" or some other examples on main page: - stdin .byLineCopy .array .sort!((a, b) => a > b) // descending order .each!writeln; -- Thought I'd add a link to Walter's good article laying out the case for such component programming with ranges: http://www.drdobbs.com/architecture-and-design/component-programming-in-d/240008321
Re: SOLID principals in D
On Saturday, 16 June 2018 at 19:20:30 UTC, FromAnotherPlanet wrote: - Interface segregation principal: Essentially breaking the program up into smaller interfaces. Sometimes only consistent of one or two methods/properties (can feed into 'S' of SOLID quite nicely). - Dependency inversion principle: Things should depend on abstractions not concretions. Strongly enables dependency injection. D seems to have all of the features *required* to make this happen, but I guess the real question is the last two, and more specifically the last one. Then D supports everything you need (and even better, just look at interface with contracts: https://dlang.org/spec/interface.html) Interface segregation example: https://run.dlang.io/gist/6aa1710dd5a8327f20e605b0ac3b978f Keep in mind that D doesn't support multiple inheritance, so if you want to follow DRY principle, you need to use interfaces + template mixins to make it happen (so in this point D is way better than the plain Java, because D's templates mixins are like traits). Dependency injection is also supported. However, D doesn't supply any DI containers in its standard library, so you have to rely on 3rd-party components, or implement it on your own. Look at this page: https://wiki.dlang.org/Dependency_Injection_Containers The most popular and actively maintained are "aedi" and "poodinis".
Re: SOLID principals in D
What's the differences in the approaches between SOLID and component programming? Are they orthogonal? Or can they be used together?
Re: SOLID principals in D
On Sunday, 17 June 2018 at 12:24:35 UTC, FromAnotherPlanet wrote: What's the differences in the approaches between SOLID and component programming? Are they orthogonal? Or can they be used together? It looks like they have some overlap, but are not the same. SOLID seems focused on OOP, whereas component programming isn't and has its own abstraction of ranges. I suggest you read the article and contrast them for yourself, as I'm not that familiar with SOLID.
