IdStack

TIdSocketList is a TObject descendant that specifies the interface used for a container created for a list of socket descriptors. 

TIdSocketList is the ancestor class for the type used to represent the properties that store socket handles returned from the Select() API in a protocol stack implementation. 

Nearly all of the methods in TIdSocketList are declared as abstract virtual methods, and must be implemented in a descendant class like TIdSocketListWindows, TIdSocketListDotNet, and TIdSocketListLinux. 

TIdSocketList implements a TCriticalSection to protect access to the resources in the container in multi-threaded applications.

TIdSocketList is descended from TObject, instead of the collection classes or object list containers in Delphi. TIdSocketList is created often in the Indy library, and the extra overhead associated with those classes is undesirable.

TObject 

TIdStack.Select