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Clarify cl-defstruct doc string and manual entry somewhat
* doc/misc/cl.texi (Structures): Rename the slot "name" in the examples to "first-name", since we're talking about the names of slots a lot here, and having a slot with the name "name" makes the examples somewhat confusing. * lisp/emacs-lisp/cl-macs.el (cl-defstruct): Clarify certain things about slots (bug#14278).
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2 changed files with 44 additions and 39 deletions
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@ -3962,22 +3962,22 @@ In the simplest case, @var{name} and each of the @var{slots}
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are symbols. For example,
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@example
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(cl-defstruct person name age sex)
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(cl-defstruct person first-name age sex)
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@end example
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@noindent
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defines a struct type called @code{person} that contains three
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slots. Given a @code{person} object @var{p}, you can access those
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slots by calling @code{(person-name @var{p})}, @code{(person-age @var{p})},
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and @code{(person-sex @var{p})}. You can also change these slots by
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using @code{setf} on any of these place forms, for example:
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defines a struct type called @code{person} that contains three slots.
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Given a @code{person} object @var{p}, you can access those slots by
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calling @code{(person-first-name @var{p})}, @code{(person-age
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@var{p})}, and @code{(person-sex @var{p})}. You can also change these
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slots by using @code{setf} on any of these place forms, for example:
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@example
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(cl-incf (person-age birthday-boy))
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@end example
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You can create a new @code{person} by calling @code{make-person},
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which takes keyword arguments @code{:name}, @code{:age}, and
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which takes keyword arguments @code{:first-name}, @code{:age}, and
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@code{:sex} to specify the initial values of these slots in the
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new object. (Omitting any of these arguments leaves the corresponding
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slot ``undefined'', according to the Common Lisp standard; in Emacs
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@ -3989,7 +3989,7 @@ object of the same type whose slots are @code{eq} to those of @var{p}.
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Given any Lisp object @var{x}, @code{(person-p @var{x})} returns
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true if @var{x} is a @code{person}, and false otherwise.
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Accessors like @code{person-name} normally check their arguments
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Accessors like @code{person-first-name} normally check their arguments
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(effectively using @code{person-p}) and signal an error if the
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argument is the wrong type. This check is affected by
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@code{(optimize (safety @dots{}))} declarations. Safety level 1,
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@ -4002,13 +4002,13 @@ always print a descriptive error message for incorrect inputs.
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@xref{Declarations}.
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@example
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(setq dave (make-person :name "Dave" :sex 'male))
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(setq dave (make-person :first-name "Dave" :sex 'male))
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@result{} [cl-struct-person "Dave" nil male]
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(setq other (copy-person dave))
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@result{} [cl-struct-person "Dave" nil male]
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(eq dave other)
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@result{} nil
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(eq (person-name dave) (person-name other))
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(eq (person-first-name dave) (person-first-name other))
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@result{} t
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(person-p dave)
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@result{} t
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@ -4021,7 +4021,7 @@ always print a descriptive error message for incorrect inputs.
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@end example
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In general, @var{name} is either a name symbol or a list of a name
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symbol followed by any number of @dfn{struct options}; each @var{slot}
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symbol followed by any number of @dfn{structure options}; each @var{slot}
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is either a slot symbol or a list of the form @samp{(@var{slot-name}
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@var{default-value} @var{slot-options}@dots{})}. The @var{default-value}
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is a Lisp form that is evaluated any time an instance of the
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@ -4029,7 +4029,7 @@ structure type is created without specifying that slot's value.
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@example
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(cl-defstruct person
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(name nil :read-only t)
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(first-name nil :read-only t)
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age
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(sex 'unknown))
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@end example
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@ -4062,7 +4062,7 @@ enclosed in lists.)
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(cl-defstruct (person (:constructor create-person)
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(:type list)
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:named)
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name age sex)
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first-name age sex)
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@end example
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The following structure options are recognized.
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@ -4108,12 +4108,12 @@ option.
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(person
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(:constructor nil) ; no default constructor
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(:constructor new-person
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(name sex &optional (age 0)))
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(:constructor new-hound (&key (name "Rover")
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(first-name sex &optional (age 0)))
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(:constructor new-hound (&key (first-name "Rover")
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(dog-years 0)
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&aux (age (* 7 dog-years))
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(sex 'canine))))
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name age sex)
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first-name age sex)
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@end example
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The first constructor here takes its arguments positionally rather
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@ -4165,16 +4165,16 @@ slot descriptors for slots in the included structure, possibly with
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modified default values. Borrowing an example from Steele:
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@example
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(cl-defstruct person name (age 0) sex)
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(cl-defstruct person first-name (age 0) sex)
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@result{} person
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(cl-defstruct (astronaut (:include person (age 45)))
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helmet-size
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(favorite-beverage 'tang))
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@result{} astronaut
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(setq joe (make-person :name "Joe"))
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(setq joe (make-person :first-name "Joe"))
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@result{} [cl-struct-person "Joe" 0 nil]
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(setq buzz (make-astronaut :name "Buzz"))
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(setq buzz (make-astronaut :first-name "Buzz"))
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@result{} [cl-struct-astronaut "Buzz" 45 nil nil tang]
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(list (person-p joe) (person-p buzz))
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@ -4182,17 +4182,17 @@ modified default values. Borrowing an example from Steele:
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(list (astronaut-p joe) (astronaut-p buzz))
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@result{} (nil t)
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(person-name buzz)
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(person-first-name buzz)
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@result{} "Buzz"
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(astronaut-name joe)
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@result{} error: "astronaut-name accessing a non-astronaut"
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(astronaut-first-name joe)
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@result{} error: "astronaut-first-name accessing a non-astronaut"
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@end example
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Thus, if @code{astronaut} is a specialization of @code{person},
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then every @code{astronaut} is also a @code{person} (but not the
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other way around). Every @code{astronaut} includes all the slots
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of a @code{person}, plus extra slots that are specific to
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astronauts. Operations that work on people (like @code{person-name})
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astronauts. Operations that work on people (like @code{person-first-name})
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work on astronauts just like other people.
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@item :noinline
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@ -4230,10 +4230,10 @@ records, which are always tagged. Therefore, @code{:named} is only
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useful in conjunction with @code{:type}.
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@example
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(cl-defstruct (person1) name age sex)
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(cl-defstruct (person2 (:type list) :named) name age sex)
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(cl-defstruct (person3 (:type list)) name age sex)
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(cl-defstruct (person4 (:type vector)) name age sex)
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(cl-defstruct (person1) first-name age sex)
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(cl-defstruct (person2 (:type list) :named) first-name age sex)
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(cl-defstruct (person3 (:type list)) first-name age sex)
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(cl-defstruct (person4 (:type vector)) first-name age sex)
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(setq p1 (make-person1))
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@result{} #s(person1 nil nil nil)
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@ -4254,10 +4254,10 @@ useful in conjunction with @code{:type}.
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Since unnamed structures don't have tags, @code{cl-defstruct} is not
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able to make a useful predicate for recognizing them. Also,
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accessors like @code{person3-name} will be generated but they
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will not be able to do any type checking. The @code{person3-name}
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accessors like @code{person3-first-name} will be generated but they
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will not be able to do any type checking. The @code{person3-first-name}
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function, for example, will simply be a synonym for @code{car} in
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this case. By contrast, @code{person2-name} is able to verify
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this case. By contrast, @code{person2-first-name} is able to verify
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that its argument is indeed a @code{person2} object before
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proceeding.
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