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authordkf <donal.k.fellows@manchester.ac.uk>2018-07-02 07:44:09 (GMT)
committerdkf <donal.k.fellows@manchester.ac.uk>2018-07-02 07:44:09 (GMT)
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Documentation for [classmethod]
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@@ -39,6 +39,27 @@ used as the \fIdefScript\fR argument.
The following commands are supported in the \fIdefScript\fR for
\fBoo::define\fR, each of which may also be used in the \fIsubcommand\fR form:
.TP
+\fBclassmethod\fI name\fR ?\fIargList bodyScrip\fR?
+.VS TIP478
+This creates a class method, or (if \fIargList\fR and \fIbodyScript\fR are
+omitted) promotes an existing method on the class object to be a class
+method. The \fIname\fR, \fIargList\fR and \fIbodyScript\fR arguments are as in
+the \fBmethod\fR definition, below.
+.RS
+.PP
+Class methods can be called on either the class itself or on the instances of
+that class. When they are called, the current object (see the \fBself\R and
+\fBmy\fR commands) is the class on which they are called or the class of the
+instance on which they are called, depending on whether they are called on the
+class or an instance of the class, respectively. If called on a subclass or
+instance of the subclass, the current object is the subclass.
+.PP
+In a private definition context, the methods as invoked on classes are
+\fInot\fR private, but the methods as invoked on instances of classes are
+private.
+.RE
+.VE TIP478
+.TP
\fBconstructor\fI argList bodyScript\fR
.
This creates or updates the constructor for a class. The formal arguments to
@@ -503,6 +524,84 @@ oo::class create B {
inst m1 \fI\(-> prints "red brick"\fR
inst m2 \fI\(-> prints "blue brick"\fR
.CE
+.PP
+.VS TIP478
+This example shows how to create and use class variables. It is a class that
+counts how many instances of itself have been made.
+.PP
+.CS
+oo::class create Counted
+\fBoo::define\fR Counted {
+ \fBinitialise\fR {
+ variable count 0
+ }
+
+ \fBvariable\fR number
+ \fBconstructor\fR {} {
+ classvariable count
+ set number [incr count]
+ }
+
+ \fBmethod\fR report {} {
+ classvariable count
+ puts "This is instance $number of $count"
+ }
+}
+
+set a [Counted new]
+set b [Counted new]
+$a report
+ \fI\(-> This is instance 1 of 2\fR
+set c [Counted new]
+$b report
+ \fI\(-> This is instance 2 of 3\fR
+$c report
+ \fI\(-> This is instance 3 of 3\fR
+.CE
+.PP
+This example demonstrates how to use class methods. (Note that the constructor
+for \fBoo::class\fR calls \fBoo::define\fR on the class.)
+.PP
+.CS
+oo::class create DBTable {
+ \fBclassmethod\fR find {description} {
+ puts "DB: locate row from [self] matching $description"
+ return [my new]
+ }
+ \fBclassmethod\fR insert {description} {
+ puts "DB: create row in [self] matching $description"
+ return [my new]
+ }
+ \fBmethod\fR update {description} {
+ puts "DB: update row [self] with $description"
+ }
+ \fBmethod\fR delete {} {
+ puts "DB: delete row [self]"
+ my destroy; # Just delete the object, not the DB row
+ }
+}
+
+oo::class create Users {
+ \fBsuperclass\fR DBTable
+}
+oo::class create Groups {
+ \fBsuperclass\fR DBTable
+}
+
+set u1 [Users insert "username=abc"]
+ \fI\(-> DB: create row from ::Users matching username=abc\fR
+set u2 [Users insert "username=def"]
+ \fI\(-> DB: create row from ::Users matching username=def\fR
+$u2 update "group=NULL"
+ \fI\(-> DB: update row ::oo::Obj124 with group=NULL\fR
+$u1 delete
+ \fI\(-> DB: delete row ::oo::Obj123\fR
+set g [Group find "groupname=webadmins"]
+ \fI\(-> DB: locate row ::Group with groupname=webadmins\fR
+$g update "emailaddress=admins"
+ \fI\(-> DB: update row ::oo::Obj125 with emailaddress=admins\fR
+.CE
+.VE TIP478
.SH "SEE ALSO"
next(n), oo::class(n), oo::object(n)
.SH KEYWORDS