c# - How to implement a custom class to have only one instance per value set (not singleton) -

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• giving same data parameters same instance 1 answer

i have custom class follows 2 enumerations:

public class mcode {     public aenum { get; }     public benum b { get; }     public byte c { get; }       //some constructors , methods } 

i'd create 1 instance of each mcode (never create mcode if 1 exists same 3 values) , if ever create object contains mcode property, i'd ensure same instance property of previous object containing such mcode.

in terms of numbers: number of possible mcodes 100s number of references mcodes @ runtime 100s number of distinct mcodes in terms of values 3-10.

********************update***********************************

now tried use factory class follows:

public static class makemcode {      private static list<mcode> instances;       public static mcode instance(aenum ae, benum be, byte c)      {            var mc = instances.find(x=>x.gethashcode()==mcode.gethashcode(ae,be,c));            if (mc == null)           {                var newmc = new mcode(ae, be, c);                instances.add(newmc);                return newmc;           }           return mc;      }  } 

where have implemented required gethashcode , static gethashcode suggest below (without second seemed need new mcode in order determine hashcode, why avoided using instances.contains)

but i'm unsure how implement constructors in mcode such uses makemcode.instance , protects against mcodes being created without calling makemcode.instance

you can create static list mcodespool, , add mcodes there on creation. differ codes overwriting gethashcode() method like

return (byte)aenum * 256 * 256  +  (byte)benum * 256 * c; 

so, when construct mcode can check if mcodespool contains mcode created hashcode.

p.s. use sorted collections if plan create tons of objects.