Class/Interface/Contract -- Re: fake class in OE

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Some thougths from me ...
I hope my english is ok.


--[ <built-in> 
--[+ About An Interface 
---   
--+] 
interface Class 
  --[ About A Contract 
  -- a "contract name" is optional, 
  -- it is not to be the same name as the routine or variable. 
  -- could be used for error reporting. 
  -- If a contract is not satisfied an error will occur (aka ##error:crash()##) 
  -- example: (# is like : for namespace. I choose that to differ from namespaces -- i.e. instead of ::) 
  --   sequence message = {Class#contract[_NAME_], Class#contract[_REQUIREMENTS_]} 
  --   crash_message("Contract %s not satisfied!\nRequirements: %s", message) 
  --] 
   
  contract create 
    atom class_pointer: -1 <= return >= 0 
    export procedure create() return class_pointer 
    docline "-1 means error, >= 0 means 'This is my pointer and I love you so much!'" 
  end contract 
   
   
  --[ About @ 
  --- @ could be a routine name and will be (auto-) called if its Requirements are not satisfied 
  --- I think for ClassError it must be a procedure. 
  --- And the format (fmt) of ##error:crash_message(sequence fmt)## is optional to use 
  --- example: 
  ---   fmt could be by default: sprintf("%s is neither %d nor %d", {...}) 
  ---   fmt by user would be used like any ##sprintf##  i.e. @ClassError("...", {...}) 
  --- See: [["About A Contract"]] 
  --] 
 
  contract destroy 
    integer code return >= 1  @ClassError -- should it be @ClassError() ?? 
            or   return <= 0  @ClassError --- 
    export function destroy() return code 
    docline "<= 0 means no error and >= 1 means an error" 
  end contract 
   
  --- More (explicit) contracts if needed ... 
   
  --[ About 'magic routines' 
  --  It's magic if no function was defined 
  --  Like in other languages (Java, etc.) 
  --] 
   
  export function equal() return boolean 
  export function hash()  return sequence 
   
  export function serialize() return sequence 
  export procedure deserialize() 
  [...] 
end interface 
--] 
 
interface Animal: Class -- ": Class" is optional, any class/interface/contract/etc. will be inherited from Class 
  contract name 
    sequence name = "Animal" 
  end contract 
   
  -- Return name of Animal 
  contract 
    export function get_name(): string 
    return name: sequence 
  end contract 
   
  --- override in an interface is a 'silent' contract: this must be overridden! 
  override function equal() -- should a type-hint be required ?? 
  override function hash()  ---  
end interface 
 
class Cow: Animal 
  sequence name = "Cow" 
 
  export function get_name(): string 
    return name 
  end function 
 
  export function equal(@Class seq) 
     return equal(seq#name, name) 
  end function 
 
  export function hash() 
    return name 
  end function 
end class 
 
class Goat: Cow 
  override sequence name = "Goat" 
  [...] 
end class 

Use (strict)

Goat#get_name() 

Use (compat)

class_pointer goat_     = getclass("Goat") -- or get_class("Goat")  -- is case-insensitive 
method_return goat_name = getmethod(goat_, "get_name", {})          -- same here 


class_pointer is an atom
method_return is a sequence; {atom class_pointer, sequence method_name, object return_value}

But I prefer

class_pointer goat_ = class:new("Goat") 
method_return goat_name = class:method(goat_, "get_name", {}) 
-- or class:call(...) 
-- or class:func(..) / class:proc(...) 

I know this is a big thing to implement.
It could be implemented step by step.

The point is to use interfaces and contracts.
Better documentation to read by an IDE/Editor and any human.

The first step could be to ignore 'interface ... end interface'.
It's than a stub. Used for documentation, only.

--[ About "doc...end doc" and "docline" 
--- I think it's good practice to say which comment is more than a hint for the code owner. 
--] 
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