Library design

[Rutger via Digitalmars-d-learn]

On Friday, 13 June 2014 at 05:54:02 UTC, TheFlyingFiddle wrote:
> On Friday, 13 June 2014 at 04:11:38 UTC, Rutger wrote:
>> I'm trying to create a minimal tweening library in D based on 
>> the
>> commonly used easing equations by Robert Penner
>> (http://www.robertpenner.com/easing/).
>> One of the goals with the design of the library is that any
>> numeric type should be tweenable.(The user of the library
>> shouldn't have to do any casting of their own etc) Now how do I
>> go about and design a data structure that can take either 
>> floats,
>> ints or doubles, store them and modify them?
>>
>> This is what I hacked together earlier today:
>>
>>
>> abstract class TweenWrapper{
>> 		
>> }
>>
>>
>> class Tween(T) : TweenWrapper{
>> 		
>>    		T owner;
>> 		
>> 		string[] members;
>> 		
>> 		/** Duration in milliseconds */
>> 		int duration;
>> 		
>> 		/** Elapsed time in milliseconds */
>> 		int elapsedTime;
>> 		
>> 		bool isComplete;
>> 		
>> 		/** Type of easing */
>> 		EasingType easingType;
>> 			
>> }
>>
>> TweenWrapper is just what it sounds like, a wrapper so I don't
>> have to specify any type for the container holding the Tween
>> objects(DList!TweenWrapper).
>>
>> __traits(getMember, owner, members[0]) =
>> valueReturnedFromEasingFunction;
>> Was How I planned to use this class.. but you know, compile 
>> time
>> only.
>>
>>
>> Let me know if this isn't enough to go on.
>> Is what I'm asking even possible(the easy way) in D?
>>
>>
>> TL;DR
>> Help me make D Dynamic!
>
>
> From what i can tell you want something similar to this.
>
> interface ITween
> {
>    void update(int elapsedTime);
> }
>
> class Tween(T, string member) : ITween
> {
>    //Expands to
>    //|alias memberType = typeof(T.memberName);|
>
>    mixin("alias memberType = typeof("
>           ~ T.stringof ~ "." ~ member ~ ");");
>
>    memberType from;
>    memberType to;
>    EasingType type;
>
>    int duration;
>    int elapsedTime;
>
>    T owner;
>
>    @property bool isComplete()
>    {
>       return elapsedTime >= duration;
>    }
>
>    void update(int time)
>    {
>       elapsedTime = min(elapsedTime + time, duration);
>       double amount = elapsedTime / cast(double)duration;
>       auto tweened = ease(type, from, to, amount);
>       __traits(getMember, owner, member) = tweened;
>    }
> }
>
> Where ease is a method that will look something like this:
>
> T ease(T)(EasingType type, T from, T to, double amount) 
> if(isNumeric!T)
> {
>    double result;
>    if(type == EasingType.linear)
>      result = linearEase(amount);
>    else
>       assert(0, "Not yet implemented");
>
>    return cast(T)((to - from) * result + from));
> }
>
> double linearEase(double amount)
> {
>    return amount;
> }
>
> This will work for all number types.
>
> Hope this was helpful.


Gonna try this later, thanks a lot!