[comment {-*- tcl -*- doctools manpage}]
[manpage_begin oo::util n 1.1]
[see_also snit(n)]
[keywords callback]
[keywords {class methods}]
[keywords {class variables}]
[keywords {command prefix}]
[keywords currying]
[keywords {method reference}]
[keywords {my method}]
[keywords singleton]
[keywords TclOO]
[copyright {2011-2013 Andreas Kupries, BSD licensed}]
[moddesc {Utility commands for TclOO}]
[titledesc {Utility commands for TclOO}]
[category  Utility]
[require Tcl 8.5]
[require TclOO]
[require oo::util [opt 1.1]]
[description]
[para]

This package provides a convenience command for the easy specification
of instance methods as callback commands, like timers, file events, Tk
bindings, etc.

[section {COMMANDS}]

[list_begin definitions]
[comment {- - -- --- ----- -------- ------------- ---------------------}]
[call [cmd mymethod] [arg method] [opt [arg arg]...]]

This command is available within instance methods. It takes a method
name and, possibly, arguments for the method and returns a command
prefix which, when executed, will invoke the named method of the
object we are in, with the provided arguments, and any others supplied
at the time of actual invokation.

[para] Note: The command is equivalent to and named after the command
provided by the OO package [package snit] for the same purpose.

[comment {- - -- --- ----- -------- ------------- ---------------------}]
[call [cmd classmethod] [arg name] [arg arguments] [arg body]]

This command is available within class definitions. It takes a method
name and, possibly, arguments for the method and creates a method on the
class, available to a user of the class and of derived classes.

[para] Note: The command is equivalent to the command [cmd typemethod]
provided by the OO package [package snit] for the same purpose.

[para] Example
[example {
oo::class create ActiveRecord {
    classmethod find args { puts "[self] called with arguments: $args" }
}
oo::class create Table {
    superclass ActiveRecord
}
puts [Table find foo bar]
# ======
# which will write
# ======
# ::Table called with arguments: foo bar
}]

[comment {- - -- --- ----- -------- ------------- ---------------------}]
[call [cmd classvariable] [opt [arg arg]...]]

This command is available within instance methods. It takes a series
of variable names and makes them available in the method's scope. The
originating scope for the variables is the class (instance) the object
instance belongs to. In other words, the referenced variables are shared
between all instances of their class.

[para] Note: The command is roughly equivalent to the command
[cmd typevariable] provided by the OO package [package snit] for the
same purpose. The difference is that it cannot be used in the class
definition itself.

[para] Example:
[example {
% oo::class create Foo {
    method bar {z} {
        classvariable x y
        return [incr x $z],[incr y]
    }
}
::Foo
% Foo create a
::a
% Foo create b
::b
% a bar 2
2,1
% a bar 3
5,2
% b bar 7
12,3
% b bar -1
11,4
% a bar 0
11,5
}]

[comment {- - -- --- ----- -------- ------------- ---------------------}]
[call [cmd link] [arg method]...]
[call [cmd link] "{[arg alias] [arg method]}..."]

This command is available within instance methods. It takes a list of
method names and/or pairs of alias- and method-name and makes the
named methods available to all instance methods without requiring the
[cmd my] command.

[para] The alias name under which the method becomes available defaults
to the method name, except where explicitly specified through an
alias/method pair.

[para] Examples:
[example {
    link foo
    # The method foo is now directly accessible as foo instead of my foo.

    link {bar foo}
    # The method foo is now directly accessible as bar.

    link a b c
    # The methods a, b, and c all become directly acessible under their
    # own names.
}]

The main use of this command is expected to be in instance constructors,
for convenience, or to set up some methods for use in a mini DSL.

[comment {- - -- --- ----- -------- ------------- ---------------------}]
[call [cmd ooutil::singleton] [opt [arg arg]...]]

This command is a meta-class, i.e. a variant of the builtin
[cmd oo::class] which ensures that it creates only a single
instance of the classes defined with it.

[para] Syntax and results are like for [cmd oo::class].

[para] Example:
[example {
% oo::class create example {
   self mixin singleton
   method foo {} {self}
}
::example
% [example new] foo
::oo::Obj22
% [example new] foo
::oo::Obj22
}]

[list_end]

[section AUTHORS]
Donal Fellows, Andreas Kupries

[vset CATEGORY oo::util]
[include ../doctools2base/include/feedback.inc]
[manpage_end]
