Class, constructor and inherance.

[holo via Digitalmars-d-learn]

>>>>
>>>> I want to ask you for  advises what i could do with that 
>>>> class to make
>>>> it looks more "pro"/elegant/build in "proper way". Probably 
>>>> there are
>>>> lot of mistakes which all beginners are doing.
>>>>
>>>> eg.: Did i use interface correctly?
>>>
>>> You are reasonably close:
>>> credential sig = new sigv4();
>>
>> Why are you creating sigv4 object with type credential? How in 
>> your
>> opinion should look interface for such class?
>>
>>>
>>> Although go is not really doing what I expect it to do.
>>> To me go should be dedicated to performing a request given 
>>> what ever
>>> you need for just that request. The class sigv4 is your 
>>> global state
>>> aka what doesn't change per request.
>>> To me what go returns is whatever is the common denominator 
>>> for what
>>> you need from it is.
>>
>> Not sure if i correctly understood that. Do you propose to 
>> take out eg
>> signing process from go function and let it only to make 
>> requests?
>> Signature is depending on kind of request and accurate time 
>> when request
>> is send. That is why i all that things put to it.
>
> The implementation such as sigv4 can be configured with as much 
> detail as possible extra that you need.
> The method go can for instance do what ever it needs to, to for 
> fill it's goal.
>
>>>
>>> From what I can see, you probably want go to take the payload 
>>> as an
>>> argument.
>>> That way you can reuse an instance of sigv4. Which is the 
>>> ultimate goal.
>>
>> In plan i wanted to change variables per request that why i 
>> left that
>> public variables and created that arguments for constructor - 
>> to have
>> possibility to change that  values durring creation of object.
>>
>> On example, im expecting it will be behaving like that:
>>
>> sigv4 obj = new sigv4();
>> content =  obj.go();    //will get instances list
>> obj.request_parameters = 
>> "Action=DescribeRegions&Version=2013-10-15"
>> content2 = obj.go();    //will get list  of regions
>> destroy(obj);
>>
>> so that go will get me back what i need per request not per 
>> one object
>> live, or it wont work like that?
>
> It indeed should not.
> Also remember go is currently returning an integer. Not data 
> from the request.

I test it with such code:

void main()
{
	SigV4 sig = new SigV4();
	writeln(sig.go);
	sig.requestParameters = 
"Action=DescribeRegions&Version=2013-10-15";
         writeln(sig.go());
}

Actually it is working, first it returned to me default request 
DescribeInstances and right after that request DescirbeRegions. I 
understand that, before i will start parsing it with xml lib i 
need to convert it to string. Should it be solved in other way?

>
>> go method returns xml form (need to find out how force AWS to 
>> return
>> JSON cos i saw xml module in dlang is deprecated) with 
>> structures
>> depends on query - in default query that will be list of  
>> instances with
>> all  parameters. That xml file i want to parse in higher
>> classes/functions (different class for different request).
>
> If you need to use std.xml use it. We don't appear to be 
> replacing it any time soon.
>
> So here is the thing. You are tieing your usage of the API to 
> SigV4 standard. This is bad bad bad. Any updates or changes to 
> it, will cause problems. If you want to tie yourself to said 
> standard, then you don't need OOP.

How it could be solved in that case to not be tied to SigV4? If 
there will came some other request signing process it will need 
to be implement in that "go" function. Is there possibility to 
make it universal for all kind of signing processes? How it 
should be done in OOP (some example, pseudo code)? Or i missed 
what you are pointing to?

>
> Another thing, you may want to consider to use an interface as 
> the return type of go. That way your implementation of it can 
> have extra fields/methods which if you know that it is sigv4 
> you can cast to, to get access to, should you need it.

It interesting what you wrote. Can you show me some example 
(pseudo code) how it can be implemented and how it could be used? 
It think that it is what you wrote in previous post:

Credential sigv4 = new sigv4();

Remember im really beginner and some obvious things are not 
necessarily such for me. :)


> Also classes start with a capital letter, like Credential or 
> SigV4. And D prefers camal casing aka requestParameters for 
> variables/functions.

Updated my code according to those directions.

//holo