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Nuke GOOPS Quick Start' section, in favour of the Tutorial'

Browse source 
These sections are pretty similar in aim, but `Tutorial' is mostly
better material.

* doc/ref/goops-tutorial.texi (Class definition): Add a sentence about
  what slots are.

* doc/ref/goops-tutorial.texi (Tutorial): Remove repetition of the Stk
  origin, and index entries that are overly general in the context of
  the whole Guile manual.

  (Generic functions): Add text here about the nature of methods,
  previously in Quick Start.

* doc/ref/goops.texi (Quick Start): Move `Built-in classes' subsection
  to be part of `Introspection'.  Delete the rest, apart from snippets
  moved into Tutorial.
This commit is contained in:
Neil Jerram 2010-10-13 23:16:29 +01:00
parent 2b41a37b3c
commit 37d6f737e7
2 changed files with 71 additions and 140 deletions
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61
doc/ref/goops-tutorial.texi
View file

@ -30,21 +30,13 @@
@c Guile
@c @end macro
This section introduces the @goops{} package in more detail. It was
originally written by Erick Gallesio as an appendix for the STk
reference manual, and subsequently adapted to @goops{}.
The procedures and syntax described in this tutorial are provided by
Guile modules that may need to be imported before being available.
The main @goops{} module is imported by evaluating:
To start using @goops{} you first need to import the @code{(oop goops)}
module. You can do this at the Guile REPL by evaluating:
@lisp
(use-modules (oop goops))
@end lisp
@findex (oop goops)
@cindex main module
@cindex loading
@cindex preparing
@menu
* Class definition::
@ -68,13 +60,16 @@ of @code{define-class} is close to CLOS @code{defclass}:
@var{class-option} @dots{})
@end lisp
@var{class} is the class being defined. The list of
@var{superclass}es specifies which existing classes, if any, to
inherit slots and properties from. Each @var{slot-description} gives
the name of a slot and optionally some ``properties'' of this slot;
for example its initial value, the name of a function which will
access its value, and so on. Slot descriptions and inheritance are
discussed more below. For class options, see @ref{Class Options}.
@var{class} is the class being defined. The list of @var{superclass}es
specifies which existing classes, if any, to inherit slots and
properties from. @dfn{Slots} hold per-instance@footnote{Usually --- but
see also the @code{#:allocation} slot option.} data, for instances of
that class --- like ``fields'' or ``member variables'' in other object
oriented systems. Each @var{slot-description} gives the name of a slot
and optionally some ``properties'' of this slot; for example its initial
value, the name of a function which will access its value, and so on.
Slot descriptions and inheritance are discussed more below. For class
options, see @ref{Class Options}.
@cindex slot
As an example, let us define a type for representing a complex number
@ -556,6 +551,38 @@ However, this result is not too much readable; using the function
@node Generic functions
@subsection Generic functions
A GOOPS method is like a Scheme procedure except that it is specialized
for a particular set of argument classes, and will only be used when the
actual arguments in a call match the classes in the method definition.
@lisp
(define-method (+ (x <string>) (y <string>))
(string-append x y))
(+ "abc" "de") @result{} "abcde"
@end lisp
A method is not formally associated with any single class (as it is in
many other object oriented languages), because a method can be
specialized for a combination of several classes. If you've studied
object orientation in non-Lispy languages, you may remember discussions
such as whether a method to stretch a graphical image around a surface
should be a method of the image class, with a surface as a parameter, or
a method of the surface class, with an image as a parameter. In GOOPS
you'd just write
@lisp
(define-method (stretch (im <image>) (sf <surface>))
...)
@end lisp
@noindent
and the question of which class the method is more associated with does
not need answering.
A generic function is a collection of methods with the same name but
different sets of specializing argument classes.
@menu
* Generic functions and methods::
* Next-method::

150
doc/ref/goops.texi
View file

@ -30,7 +30,6 @@ overriding or redefining those methods.
@menu
* Copyright Notice::
* Quick Start::
* Tutorial::
* Defining New Classes::
* Creating Instances::
@ -68,128 +67,6 @@ The material has been adapted for use in Guile, with the author's
permission.
@node Quick Start
@section Quick Start
To start using GOOPS, load the @code{(oop goops)} module:
@lisp
(use-modules (oop goops))
@end lisp
We're now ready to try some basic GOOPS functionality.
@menu
* Methods::
* Built-in classes::
* User-defined classes::
@end menu
@node Methods
@subsection Methods
A GOOPS method is like a Scheme procedure except that it is
specialized for a particular set of argument classes.
@lisp
(define-method (+ (x <string>) (y <string>))
(string-append x y))
(+ "abc" "de") @result{} "abcde"
@end lisp
If @code{+} is used with arguments that do not match the method's
classes, Guile falls back to using the normal Scheme @code{+} procedure.
@lisp
(+ 1 2) @result{} 3
@end lisp
@node Built-in classes
@subsection Built-in classes
There are built-in classes like @code{<string>}, @code{<list>} and
@code{<number>} corresponding to all the Guile Scheme types. You can
use the @code{is-a?} predicate to ask whether any given value belongs to
a given class, or @code{class-of} to discover the class of a given
value.
@lisp
(is-a? 2.3 <number>) @result{} #t
(is-a? 2.3 <real>) @result{} #t
(is-a? 2.3 <string>) @result{} #f
(is-a? '("a" "b") <string>) @result{} #f
(is-a? '("a" "b") <list>) @result{} #t
(is-a? (car '("a" "b")) <string>) @result{} #t
(is-a? <string> <class>) @result{} #t
(is-a? <class> <string>) @result{} #f
(class-of 2.3) @result{} #<<class> <real> 908c708>
(class-of #(1 2 3)) @result{} #<<class> <vector> 908cd20>
(class-of <string>) @result{} #<<class> <class> 8bd3e10>
(class-of <class>) @result{} #<<class> <class> 8bd3e10>
@end lisp
@node User-defined classes
@subsection User-defined classes
You can, of course, also define new classes. The GOOPS term for
``fields'' or ``member variables'' is @dfn{slots}, and the main thing
you have to specify, when defining a new class, is what its slots will
be, and how they will be initialised and accessed.
@lisp
(define-class <2D-vector> ()
(x #:init-value 0 #:accessor x-component #:init-keyword #:x)
(y #:init-value 0 #:accessor y-component #:init-keyword #:y))
@end lisp
Methods are not formally part of a specific class's definition,
because a single method can be associated with several classes. If
you've studied object orientation in non-Lispy languages, you may
remember discussions such as whether a method to stretch a graphical
image around a surface should be a method of the image class, with a
surface as a parameter, or a method of the surface class, with an image
as a parameter. In the generic function approach that GOOPS provides,
this question does not arise.
Here we customise @code{write} for the new class, so that
@code{<2D-vector>} objects will be nicely printed:
@lisp
(use-modules (ice-9 format))
(define-method (write (obj <2D-vector>) port)
(format port "<~S, ~S>" (x-component obj) (y-component obj)))
@end lisp
To make an @dfn{instance} or @dfn{object} of your new class, use
@code{make} together with the class and any initialisation arguments:
@lisp
(define v (make <2D-vector> #:x 3 #:y 4))
v @result{} <3, 4>
(is-a? v <2D-vector>) @result{} #t
(class-of v) @result{} #<<class> <2D-vector> 40241ac0>
@end lisp
Here is another method that is specialised for @code{<2D-vector>}
objects, to add two of them together:
@lisp
(define-method (+ (x <2D-vector>) (y <2D-vector>))
(make <2D-vector>
#:x (+ (x-component x) (x-component y))
#:y (+ (y-component x) (y-component y))))
(+ v v) @result{} <6, 8>
@end lisp
@node Tutorial
@section Tutorial
@include goops-tutorial.texi
@ -1234,6 +1111,7 @@ GOOPS equivalents --- to be obtained dynamically, at run time.
* Classes::
* Slots::
* Instances::
* Built-in classes::
* Generic Functions::
* Generic Function Methods::
@end menu
@ -1400,6 +1278,32 @@ Implementation notes: @code{is-a?} uses @code{class-of} and
@code{class-precedence-list} to obtain the class precedence list for
@var{object}.
@node Built-in classes
@subsection Built-in classes
There are built-in classes like @code{<string>}, @code{<list>} and
@code{<number>} corresponding to all the Guile Scheme types. You can
use the @code{is-a?} predicate to ask whether any given value belongs to
a given class, or @code{class-of} to discover the class of a given
value.
@lisp
(is-a? 2.3 <number>) @result{} #t
(is-a? 2.3 <real>) @result{} #t
(is-a? 2.3 <string>) @result{} #f
(is-a? '("a" "b") <string>) @result{} #f
(is-a? '("a" "b") <list>) @result{} #t
(is-a? (car '("a" "b")) <string>) @result{} #t
(is-a? <string> <class>) @result{} #t
(is-a? <class> <string>) @result{} #f
(class-of 2.3) @result{} #<<class> <real> 908c708>
(class-of #(1 2 3)) @result{} #<<class> <vector> 908cd20>
(class-of <string>) @result{} #<<class> <class> 8bd3e10>
(class-of <class>) @result{} #<<class> <class> 8bd3e10>
@end lisp
@node Generic Functions
@subsection Generic Functions