The choice of whether to use WITH-SLOTS versus WITH-ACCESSORS is the same as the choice between SLOT-VALUE and an accessor function: low-level code that provides the basic functionality of a class may use SLOT-VALUE or WITH-SLOTS to directly manipulate slots in ways not supported by accessor functions or to explicitly avoid the effects of auxiliary methods that may have been defined on the accessor functions. WITH-SLOTS provides direct access to the slots, as if by SLOT-VALUE, while WITH-ACCESSORS provides a shorthand for accessor methods. The form of WITH-ACCESSORS is the same as WITH-SLOTS except each element of the slot list is a two-item list containing a variable name and the name of an accessor function. However, :class slots are accessed the same as :instance slots--they're accessed with SLOT-VALUE or an accessor function, which means you can access the slot value only through an instance of the class even though it isn't actually stored in the instance.

These machines can be found at various locations, including grocery stores, banks, and even some casinos. And if you decide you want to directly access the slot value in order to avoid running auxiliary methods, it gets even more cluttered. As I just discussed, you don't want callers to be able to directly set the balance, but for other slots, such as customer-name, you may also want to provide a function to set them. The name of a SETF function is a two-item list whose first element is the symbol setf and whose second element is a symbol, typically the name of a function used to access the place the SETF function will set. While using accessor functions will make your code easier to maintain, they can still be a bit verbose. There's nothing hard about writing these accessor functions, but it wouldn't be in keeping with The Lisp Way to have to write them all by hand.

Thus, it's possible for all instances of one class to share a :class slot while instances of a subclass may each have their own :instance slot of the same name. On the other hand, passing an initarg to MAKE-INSTANCE will set the value, affecting all instances of the class. Python.11 Rather, class-allocated slots are used primarily to save space; if you're going to create many instances of a class and all instances are going to have a reference to the same object--say, a pool of shared resources--you can save the cost of each instance having its own reference by making the slot class-allocated. The :initform and :initarg options have essentially the same effect except the initform is evaluated once when the class is defined rather than each time an instance is created. A slot specifier that includes options such as :initarg or :initform is written as a list starting with the name of the slot win followed by the options. Thus, DEFCLASS supports three slot options that allow you to automatically create reader and writer functions for a specific slot. The first two involve adding options to the slot specifier in the DEFCLASS form: with the :initarg option, you can specify a name that can then be used as a keyword parameter to MAKE-INSTANCE and whose argument will be stored in the slot.

On the other hand, :initargs needn't be exclusive--each :initarg option in a slot specifier creates a keyword parameter that can be used to initialize the slot; multiple parameters don't create a conflict, so the new slot specifier contains all the :initargs. In the edge case, when the software is relatively simple web service while an infrastructure contains WAF and API Gateway deployed in front of the AWS Lambda Functions running across multiple AZ, the response time may characterize more infra rather than software. Response time and latency are distinct concepts that play crucial roles in describing performance of the web applications. So gather your friends or family next time you play-there’s no telling who will take home the victory. In this case, the applicable method will be one provided by the implementation, specialized on STANDARD-OBJECT. Since you don't want to disturb that, the most common way to add custom initialization code is to define an :after method specialized on your class.6 For instance, suppose you want to add a slot account-type that needs to be set to one of the values :gold, :silver, or :bronze based on the account's initial balance.