Re: Generics instantiate problems
Here are complete codes which can succeed to compile.
import strformat
import ../src/shene/mcall
# Constructor injection
type
Animal*[T] = object
sleepImpl: proc (a: T) {.nimcall, gcsafe.}
barkImpl: proc (a: T, b: int, c: int): string {.nimcall, gcsafe.}
danceImpl: proc (a: T, b: string): string {.nimcall, gcsafe.}
Phone*[T] = object
playImpl: proc (a: T) {.nimcall, gcsafe.}
Cat* = object
cid: int
Iphone* = object
pid: int
People*[T, U] = object
id: int
pet: must(Animal, T)
phone: must(Phone, U)
proc sleep*(a: Cat) =
discard
proc bark*(a: Cat, b: int, c: int): string =
result = fmt"{a.cid + b + c}"
proc dance*(a: Cat, b: string): string =
result = fmt"{b}"
proc play*(a: Phone) =
echo "Hello, the phone is playing the music."
proc play*(a: Iphone) =
echo "Hello, the iphone is playing the music."
proc initCat*(cid: int): must(Animal, Cat) =
result.cid = cid
result.sleepImpl = sleep
result.barkImpl = bark
result.danceImpl = dance
proc initPhone*(pid: int): must(Phone, Iphone) =
result.pid = pid
result.playImpl = play
proc initPeople*[T, U](pet: Must[Animal[T], T], phone: Must[Phone[U], U]):
People[T, U] =
result.id = 2333
result.pet = pet
result.phone = phone
proc prepare(p: People[Cat, Iphone]) =
doAssert p.pet.call(barkImpl, 13, 14) == "40"
p.pet.call(sleepImpl)
doAssert p.pet.call(danceImpl, "Hello") == "Hello"
doAssert p.pet.cid == 13
p.phone.call(playImpl)
doAssert p.phone.pid == 2333
let pet = initCat(13)
let phone = initPhone(2333)
let p = initPeople[Cat, Iphone](pet, phone)
prepare(p)
Run
Re: Generics instantiate problems
Hi, I want to implement `interface` or `dependency injection pattern`. Finally
I want to implement an extensible web framework. For example, I have a Context
object containing a Logger attributes. I just define the interfaces that Logger
should satisfy. Then users can pass their own Logger instance to construct
Context object. My goal is to achieve a loosely coupled application.
However using function pointers directly makes it hard to extend object.
type
Animal* = object
id: int
sleepImpl: proc (a: Animal) {.nimcall, gcsafe.}
barkImpl: proc (a: Animal, b: int, c: int): string {.nimcall, gcsafe.}
danceImpl: proc (a: Animal, b: string): string {.nimcall, gcsafe.}
People* = object
pet: Animal
proc sleep(a: Animal) =
discard
proc bark(a: Animal, b: int, c: int): string =
result = $(a.id + b + c)
proc dance(a: Animal, b: string): string =
result = b
proc newAnimal*(id: int): Animal =
result.id = 1314
result.sleepImpl = sleep
result.barkImpl = bark
result.danceImpl = dance
let people = People(pet: newAnimal(12))
doAssert people.pet.barkImpl(people.pet, 12, 14) == "1340"
Run
If I can't use generics to implement interfaces, I maybe implement something
like `vtables` in C++ or `fat pointer` in Rust(Using macros or so).
Experiment Code:
[https://github.com/xflywind/shene](https://github.com/xflywind/shene)
Re: Generics instantiate problems
What do you want to code? Can you express it in English? Perhaps using generics is not the best way to express it. Or do you want explicitly to use and learn generics?
Re: File not found error EVERY TIME
When you type `nim -v` under Bash, what do you get? Just to be sure that your `file not found` message is about not finding the Nim compiler or your source file...
Re: File not found error EVERY TIME
I think we'll need a little more information to be able to properly help you. Depending on the exact error this could mean one of several things: * The compiler cannot find the input file `filename.nim` * Your program is importing another nim file that cannot be found. * Your program is trying to open another file that cannot be found. Please copy and paste the command you are running and the exact output. It may also be helpful to show your nim file. If your nim file is more than a few lines, please try to create a small file, ideally less than 10 lines, that causes the same error to occur and post that as well.
Re: Generic function resolution
It may be a bug or an implementation detail. Either way I would report the issue on github.
Re: Generic function resolution
It's not actually calling proc g[T](d: string) Run without B. What it's doing is instantiate g1 withB instantiate g2 withB instantiate g1 withC instantiate g2 withC call g1 withB call g2 withC It only comes up when you explicitly pass in generic parameters. All functions that match the generic parameters are instantiated.
Re: How to set up/start a Project?
Just to be sure, are you using the command `Nim` (uppercase N) or `nim` (lowercase n)? The command is `nim` (lowercase n).
Re: How to set up/start a Project?
And there is my next problem. If i try to run anything with Nim c -r filename.nim it gives a file not found error. even if i use f6 in VS Code
Re: How to set up/start a Project?
Thank you for the links it was hard for me to find anything
Re: How to set up/start a Project?
Thank you, I'll look into it
File not found error EVERY TIME
Every time I try to run a nim file in BASH (Nim c -r filename.nim) or compile and run in VS Code it gives me a file not found error. Is there a way to fix this?
Re: How to set up/start a Project?
This is project structure I use: [https://github.com/treeform/nimtemplate](https://github.com/treeform/nimtemplate)
Generics instantiate problems
Hello, I have some problems with generics. I have four similar situations in which only one can succeed. Failed case one: [https://play.nim-lang.org/#ix=2r7Q](https://play.nim-lang.org/#ix=2r7Q) type Must*[U: object; T: object | ref object] = object impl*: U data*: T Animal[T] = object Cat = object template must(a, b: typed): untyped = Must[a[b], b] var a: must(Animal, Cat) # failed proc initZ[T](must: Must[Animal[T], T]) = discard Run Failed case two: [https://play.nim-lang.org/#ix=2r7R](https://play.nim-lang.org/#ix=2r7R) type Must*[U: object; T: object | ref object] = object impl*: U data*: T Animal[T] = object Cat = object template must(a, b: typed): untyped = Must[a[b], b] var a: must(Animal, Cat) # failed proc init[T](must: must(Animal, T)) = discard Run Failed case three: [https://play.nim-lang.org/#ix=2r7S](https://play.nim-lang.org/#ix=2r7S) type Must*[U; T: object | ref object] = object impl*: U data*: T Animal[T] = object Cat = object template must(a, b: typed): untyped = Must[a[b], b] var a: must(Animal, Cat) # failed proc init[T](must: must(Animal, T)) = discard Run Successive Case: [https://play.nim-lang.org/#ix=2r7U](https://play.nim-lang.org/#ix=2r7U) type Must*[U; T: object | ref object] = object impl*: U data*: T Animal[T] = object Cat = object template must(a, b: typed): untyped = Must[a[b], b] var a: must(Animal, Cat) # succeded proc initZ[T](must: Must[Animal[T], T]) = discard initZ[Cat](must = Must[Animal[Cat], Cat]()) Run
Generic instantiate inproblems
Hello, I have some problems with generics. I have four similar situations in which only one can succeed. Failed case one: [https://play.nim-lang.org/#ix=2r7Q](https://play.nim-lang.org/#ix=2r7Q) type Must*[U: object; T: object | ref object] = object impl*: U data*: T Animal[T] = object Cat = object template must(a, b: typed): untyped = Must[a[b], b] var a: must(Animal, Cat) # failed proc initZ[T](must: Must[Animal[T], T]) = discard Run Failed case two: [https://play.nim-lang.org/#ix=2r7R](https://play.nim-lang.org/#ix=2r7R) type Must*[U: object; T: object | ref object] = object impl*: U data*: T Animal[T] = object Cat = object template must(a, b: typed): untyped = Must[a[b], b] var a: must(Animal, Cat) # failed proc init[T](must: must(Animal, T)) = discard Run Failed case three: [https://play.nim-lang.org/#ix=2r7S](https://play.nim-lang.org/#ix=2r7S) type Must*[U; T: object | ref object] = object impl*: U data*: T Animal[T] = object Cat = object template must(a, b: typed): untyped = Must[a[b], b] var a: must(Animal, Cat) # failed proc init[T](must: must(Animal, T)) = discard Run Successive Case: [https://play.nim-lang.org/#ix=2r7U](https://play.nim-lang.org/#ix=2r7U) type Must*[U; T: object | ref object] = object impl*: U data*: T Animal[T] = object Cat = object template must(a, b: typed): untyped = Must[a[b], b] var a: must(Animal, Cat) # succeded proc initZ[T](must: Must[Animal[T], T]) = discard initZ[Cat](must = Must[Animal[Cat], Cat]()) Run
Re: Why Seq search is faster than Table search
Perhaps try the new --asm command option?
Re: How to set up/start a Project?
There's the Nim package manager [Nimble](https://github.com/nim-lang/nimble) and its README has a section on [project structure](https://github.com/nim-lang/nimble#project-structure). Also, if you use `nimble init` on the command line, it will create the structure for you to have an easy start. :-) The example files also have imports so you see how a file references others.
Re: How to set up/start a Project?
Have you tried reading some tutorials? [https://nim-lang.org/learn.html](https://nim-lang.org/learn.html) There are also videos at youtube. Generally in Nim we do not but all objects in its own source file as it is common in Java. So generally You just create one single text file for your code, and you import modules like strutils, sequitils, tables or whatever you need. Many stuff is already available without import from system module. For libraries not directly available in Nim we have external packages and the nimble or nimph package manager. Of course when your own code grows it may make sense to divide it in multiple modules. For a chess game you may have your module engine for the chess algorithm, and your module board for the display. Maybe one more for saving games to disk. The official tutorial has section about modules: [https://nim-lang.org/docs/tut1.html#modules](https://nim-lang.org/docs/tut1.html#modules) I have also written something about modules: [http://ssalewski.de/nimprogramming.html#_modules](http://ssalewski.de/nimprogramming.html#_modules) The other tutorials may contain more details.
