Package object-class
Description
All symbols from this package should normally be explicitly qualified, such as object-class:class.
Don't (:use)!
object-class
object-class ensures that special subclasses of standard-object
cluster right in front of standard-object in the class precedence list.
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Using a special subclass of standard-object in instances of a metaclass is a well-known MOP design pattern, as is automatically inserting the needed class in the direct superclasses (since the class precedence list cannot simply add classes that were not declared as direct superclasses).
But design patterns are for when you have run out of language, and we didn't run out of language because this is Common Lisp we're talking about, hence this library.
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Class object-class:object-class
compatible-metaclasses:standard-class
Description
See description for object-class:class.
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Class object-class:class
compatible-metaclasses:standard-class
Description
Classes that are instances of this class push back classes that are instances of object-class:object-class towards the back (to just before standard-object or funcallable-standard-object) in their class precedence list.
Method c2mop:compute-class-precedence-list
(class object-class:class) => precedence-list
Description
Calls object-class:push-back-to-target with the following arguments:
- The result of calling the next method;
- A function that returns true if its sole argument is an instance of
object-class:object-class; - A function that returns true if its sole argument is the class standard-object or funcallable-standard-object;
- A function of 2 arguments to-push-back and rest that returns
(nreconc to-push-back rest)if rest is true, else signals an error reporting that neither standard-object nor funcallable-standard-object were found in the class precedence list.
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Function object-class:push-back-to-target
list pushbackp-function targetp-function &optional target-callback => result
Arguments and Values
- list -- A list.
- pushbackp-function -- A function designator.
- targetp-function -- A function designator.
- target-callback -- A function designator. The default is nreconc.
- result -- A list.
Description
Let to-push-back be the empty list.
First, traverse list up to the first element for which targetp-function returns true, or to the end of the list if there is no such element.
During this traversal, if pushbackp-function is true of the element, then push it into to-push-back (in reverse order) and remove it from list, else copy it. This processing ends right before the target if it is present.
Second, concatenate the copied results from the first step to the result of calling target-callback with to-push-back and the rest of the list, which has the target as its first element if the target was present in the list.
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Class object-class:autosuperclass
class-options:options-mixin, compatible-metaclasses:standard-class
Description
Classes that are instances of this class automatically append the list of classes returned by calling ( to the end of the class' direct superclasses.object-class:autosuperclass class)
Method class-options:canonicalize-options
(class object-class:autosuperclass) &key direct-superclasses => canonicalized-options
Description
If we are initializing or direct-superclasses has been supplied, then prepend :direct-superclasses (append direct-superclasses to the results of calling the next method.()object-class:autosuperclass class)
Generic Function compatible-metaclasses:autosuperclass
class => classes
Arguments and Values
- class -- A class.
- classes -- A list of classes.
Description
Returns the list of classes that should be automatically appended to the end of the list of direct superclasses for this class.
Define a method on this generic function specializing on your metaclass to return the classes you want to append, usually one.
Methods
Method object-class:autosuperclass
(class object-class:autosuperclass) => autosuperclass
Description
Returns nil.