c# - Passing an object to a method and then calling an extenstion method on that object -

i working on method yesterday , ran strange, here dumbed down version of code: problem orderby applied in bar.populatelist method not persisting.

 class foo {     list myobjects;      public void populatemyobjects()     {         //items added list orderby not persisting.         bar.populatelist(myobjects);     } }  class bar {    public static int populatelist(list thelist)    {        foreach(var in webserbicecall)        {             thelist.add(var);        }        // orderby call sorts 'thelist' in context of method.        // when return method thelist has been populated ordering has         // reverted order items added list.        thelist.orderby(obj => obj.id);        return thelist.count;    } } 

now if update code , add ref keyword per below works: e.g. public static int populatelist(ref list thelist) , bar.populatelist(ref myobjects);

can enlighten me? thought objects passed ref? fact orderby extension method?

thanks, cian

the problem here orderby call not mutate thelist in way. instead returns new ienumerable<object> ordered. hence why not see affects of call outside method, it's not changing object.

using orderby method creates new value , hence if want calling function aware of new value must returned in manner. common places in return value or in ref/out param.

public static int populatelist(ref list<object> thelist) {   ...   thelist = thelist.orderby(obj => obj.id).tolist(); }