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author | William Joye <wjoye@cfa.harvard.edu> | 2016-12-21 22:56:22 (GMT) |
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committer | William Joye <wjoye@cfa.harvard.edu> | 2016-12-21 22:56:22 (GMT) |
commit | 98acd3f494b28ddd8c345a2bb9311e41e2d56ddd (patch) | |
tree | da1cf11e12bf524556ed195b9e811ee39fefa84b /doc/class.n | |
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Squashed 'tcl8.6/' content from commit fcdc201
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git-subtree-split: fcdc2019beb26eb8141c5ffc289e8de28bd07aa5
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diff --git a/doc/class.n b/doc/class.n new file mode 100644 index 0000000..198ae41 --- /dev/null +++ b/doc/class.n @@ -0,0 +1,136 @@ +'\" +'\" Copyright (c) 2007 Donal K. Fellows +'\" +'\" See the file "license.terms" for information on usage and redistribution +'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. +'\" +.TH class n 0.1 TclOO "TclOO Commands" +.so man.macros +.BS +'\" Note: do not modify the .SH NAME line immediately below! +.SH NAME +oo::class \- class of all classes +.SH SYNOPSIS +.nf +package require TclOO + +\fBoo::class\fI method \fR?\fIarg ...\fR? +.fi +.SH "CLASS HIERARCHY" +.nf +\fBoo::object\fR + \(-> \fBoo::class\fR +.fi +.BE +.SH DESCRIPTION +.PP +Classes are objects that can manufacture other objects according to a pattern +stored in the factory object (the class). An instance of the class is created +by calling one of the class's factory methods, typically either \fBcreate\fR +if an explicit name is being given, or \fBnew\fR if an arbitrary unique name +is to be automatically selected. +.PP +The \fBoo::class\fR class is the class of all classes; every class is an +instance of this class, which is consequently an instance of itself. This +class is a subclass of \fBoo::object\fR, so every class is also an object. +Additional metaclasses (i.e., classes of classes) can be defined if necessary +by subclassing \fBoo::class\fR. Note that the \fBoo::class\fR object hides the +\fBnew\fR method on itself, so new classes should always be made using the +\fBcreate\fR method. +.SS CONSTRUCTOR +.PP +The constructor of the \fBoo::class\fR class takes an optional argument which, +if present, is sent to the \fBoo::define\fR command (along with the name of +the newly-created class) to allow the class to be conveniently configured at +creation time. +.SS DESTRUCTOR +The \fBoo::class\fR class does not define an explicit destructor. However, +when a class is destroyed, all its subclasses and instances are also +destroyed, along with all objects that it has been mixed into. +.SS "EXPORTED METHODS" +.TP +\fIcls \fBcreate \fIname \fR?\fIarg ...\fR? +. +This creates a new instance of the class \fIcls\fR called \fIname\fR (which is +resolved within the calling context's namespace if not fully qualified), +passing the arguments, \fIarg ...\fR, to the constructor, and (if that returns +a successful result) returning the fully qualified name of the created object +(the result of the constructor is ignored). If the constructor fails (i.e. +returns a non-OK result) then the object is destroyed and the error message is +the result of this method call. +.TP +\fIcls \fBnew \fR?\fIarg ...\fR? +. +This creates a new instance of the class \fIcls\fR with a new unique name, +passing the arguments, \fIarg ...\fR, to the constructor, and (if that returns +a successful result) returning the fully qualified name of the created object +(the result of the constructor is ignored). If the constructor fails (i.e., +returns a non-OK result) then the object is destroyed and the error message is +the result of this method call. +.RS +.PP +Note that this method is not exported by the \fBoo::class\fR object itself, so +classes should not be created using this method. +.RE +.SS "NON-EXPORTED METHODS" +.PP +The \fBoo::class\fR class supports the following non-exported methods: +.TP +\fIcls \fBcreateWithNamespace\fI name nsName\fR ?\fIarg ...\fR? +. +This creates a new instance of the class \fIcls\fR called \fIname\fR (which is +resolved within the calling context's namespace if not fully qualified), +passing the arguments, \fIarg ...\fR, to the constructor, and (if that returns +a successful result) returning the fully qualified name of the created object +(the result of the constructor is ignored). The name of the instance's +internal namespace will be \fInsName\fR unless that namespace already exists +(when an arbitrary name will be chosen instead). If the constructor fails +(i.e., returns a non-OK result) then the object is destroyed and the error +message is the result of this method call. +.SH EXAMPLES +.PP +This example defines a simple class hierarchy and creates a new instance of +it. It then invokes a method of the object before destroying the hierarchy and +showing that the destruction is transitive. +.PP +.CS +\fBoo::class create\fR fruit { + method eat {} { + puts "yummy!" + } +} +\fBoo::class create\fR banana { + superclass fruit + constructor {} { + my variable peeled + set peeled 0 + } + method peel {} { + my variable peeled + set peeled 1 + puts "skin now off" + } + method edible? {} { + my variable peeled + return $peeled + } + method eat {} { + if {![my edible?]} { + my peel + } + next + } +} +set b [banana \fBnew\fR] +$b eat \fI\(-> prints "skin now off" and "yummy!"\fR +fruit destroy +$b eat \fI\(-> error "unknown command"\fR +.CE +.SH "SEE ALSO" +oo::define(n), oo::object(n) +.SH KEYWORDS +class, metaclass, object +.\" Local variables: +.\" mode: nroff +.\" fill-column: 78 +.\" End: |