c# - "Field-like events" and "events in general" clarification? -

a field-like-event way of declaring both delegate variable , event @ same time.

so field event (public event eventhandler myevent;) may translate : ( taken here)

private eventhandler _myevent;  public event eventhandler myevent {     add     {         lock (this)         {             _myevent += value;         }     }     remove     {         lock (this)         {             _myevent -= value;         }     }         } 

notice private backup field.

however , corrected jon ( comments section) , general-event doen't have backup field . :

 public event eventhandler myevent     {         add         {             console.writeline ("add operation");         }          remove         {             console.writeline ("remove operation");         }     }       

notice - no backup field.

but said winform act :

for instance, in situations there lots of events few subscribed to, have map key describing event delegate handling it. windows forms - means can have huge number of events without wasting lot of memory variables have null values.

question :

• how can winform use map thing expose events without backup field ( of delegate type)

first of "map thing" dictionary<object, eventhandler>. field of class when created contain no elements , therefore not take memory (just overhead internal structures). events subscribed delegates added dictionary , start use more memory.

consider class 50 events use 5 events, in simple scenario there 50 delegates created @ every instance of class. when using dictionary storage there 5 delegates per instance.

p.s. same principle behind dependency objects/properties in wpf.