and various supporting classes). • Client- and server-side implementions of HTTP (HTTPServer and AsyncHTTPClient). • An asynchronous networking library including the classes IOLoop and IOStream, which Queue example - a concurrent web spider Tornado’s tornado.queues module (and the very similar Queue classes in asyncio) implements an asynchronous producer / consumer pattern for coroutines, analogous to the get()/post()/etc, certain other methods in RequestHandler are designed to be overridden by sub- classes when necessary. On every request, the following sequence of calls takes place: 1. A new RequestHandler

subtype does not need to implement a custom version of map, since the generic definitions + trait classes will enable the system to select the fastest version. Here is a toy implementation of map illustrating elsize(::Type{<:A}) Return the stride between consecutive elements in the array. Optional methods De- fault defini- tion Brief description stride(A, i::Int) strides(A)[i] Return the distance in necessary. For simple functions, it is often clearer to mention the role of the arguments directly in the de- scription of the function's purpose. An argument list would only repeat information already provided

subtype does not need to implement a custom version of map, since the generic definitions + trait classes will enable the system to select the fastest version. Here is a toy implementation of map illustrating elsize(::Type{<:A}) Return the stride between consecutive elements in the array. Optional methods De- fault defini- tion Brief description stride(A, i::Int) strides(A)[i] Return the distance in necessary. For simple functions, it is often clearer to mention the role of the arguments directly in the de- scription of the function's purpose. An argument list would only repeat information already provided

toCHAPTER 13. METHODS 171 implement a custom version of map, since the generic definitions + trait classes will enable the system to select the fastest version. Here is a toy implementation of map illustrating you should always define at least one of Base.IteratorSize(IterType) and length(iter) because the de- fault definition of Base.IteratorSize(IterType) is Base.HasLength(). Sequential iteration is implemented while next !== nothing 199CHAPTER 16. INTERFACES 200 Method When should this method be defined? De- fault defi- nition Brief description Base.IteratorSize(IterType) If default is not appropriate

toCHAPTER 13. METHODS 171 implement a custom version of map, since the generic definitions + trait classes will enable the system to select the fastest version. Here is a toy implementation of map illustrating you should always define at least one of Base.IteratorSize(IterType) and length(iter) because the de- fault definition of Base.IteratorSize(IterType) is Base.HasLength(). Sequential iteration is implemented while next !== nothing 199CHAPTER 16. INTERFACES 200 Method When should this method be defined? De- fault defi- nition Brief description Base.IteratorSize(IterType) If default is not appropriate

toCHAPTER 13. METHODS 171 implement a custom version of map, since the generic definitions + trait classes will enable the system to select the fastest version. Here is a toy implementation of map illustrating you should always define at least one of Base.IteratorSize(IterType) and length(iter) because the de- fault definition of Base.IteratorSize(IterType) is Base.HasLength(). Sequential iteration is implemented while next !== nothing 199CHAPTER 16. INTERFACES 200 Method When should this method be defined? De- fault defi- nition Brief description Base.IteratorSize(IterType) If default is not appropriate

subtype does not need to implement a custom version of map, since the generic definitions + trait classes will enable the system to select the fastest version. Here is a toy implementation of map illustrating you should always define at least one of Base.IteratorSize(IterType) and length(iter) because the de- fault definition of Base.IteratorSize(IterType) is Base.HasLength(). Sequential iteration is implemented while next !== nothing 199CHAPTER 16. INTERFACES 200 Method When should this method be defined? De- fault defi- nition Brief description Base.IteratorSize(IterType) If default is not appropriate

subtype does not need to implement a custom version of map, since the generic definitions + trait classes will enable the system to select the fastest version. Here is a toy implementation of map illustrating you should always define at least one of Base.IteratorSize(IterType) and length(iter) because the de- fault definition of Base.IteratorSize(IterType) is Base.HasLength(). Sequential iteration is implemented while next !== nothing 199CHAPTER 16. INTERFACES 200 Method When should this method be defined? De- fault defi- nition Brief description Base.IteratorSize(IterType) If default is not appropriate

subtype does not need to implement a custom version of map, since the generic definitions + trait classes will enable the system to select the fastest version. Here is a toy implementation of map illustrating you should always define at least one of Base.IteratorSize(IterType) and length(iter) because the de- fault definition of Base.IteratorSize(IterType) is Base.HasLength(). Sequential iteration is implemented while next !== nothing 199CHAPTER 16. INTERFACES 200 Method When should this method be defined? De- fault defi- nition Brief description Base.IteratorSize(IterType) If default is not appropriate

subtype does not need to implement a custom version of map, since the generic definitions + trait classes will enable the system to select the fastest version. Here is a toy implementation of map illustrating you should always define at least one of Base.IteratorSize(IterType) and length(iter) because the de- fault definition of Base.IteratorSize(IterType) is Base.HasLength(). Sequential iteration is implemented while next !== nothing 199CHAPTER 16. INTERFACES 200 Method When should this method be defined? De- fault defi- nition Brief description Base.IteratorSize(IterType) If default is not appropriate