'\"
'\" Generated from file 'meta\&.man' by tcllib/doctools with format 'nroff'
'\" Copyright (c) 2011-2015 Andreas Kupries, BSD licensed
'\"
.TH "oo::util" n 1\&.2\&.2 tcllib "Utility commands for TclOO"
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.BS
.SH NAME
oo::util \- Utility commands for TclOO
.SH SYNOPSIS
package require \fBTcl 8\&.5 9\fR
.sp
package require \fBTclOO\fR
.sp
package require \fBoo::util ?1\&.2\&.2?\fR
.sp
\fBmymethod\fR \fImethod\fR ?\fIarg\fR\&.\&.\&.?
.sp
\fBclassmethod\fR \fIname\fR \fIarguments\fR \fIbody\fR
.sp
\fBclassvariable\fR ?\fIarg\fR\&.\&.\&.?
.sp
\fBlink\fR \fImethod\fR\&.\&.\&.
.sp
\fBlink\fR {\fIalias\fR \fImethod\fR}\&.\&.\&.
.sp
\fBooutil::singleton\fR ?\fIarg\fR\&.\&.\&.?
.sp
.BE
.SH DESCRIPTION
.PP
This package provides a convenience command for the easy specification
of instance methods as callback commands, like timers, file events, Tk
bindings, etc\&.
.SH COMMANDS
.TP
\fBmymethod\fR \fImethod\fR ?\fIarg\fR\&.\&.\&.?
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\&.
.sp
Note: The command is equivalent to and named after the command
provided by the OO package \fBsnit\fR for the same purpose\&.
.TP
\fBclassmethod\fR \fIname\fR \fIarguments\fR \fIbody\fR
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\&.
.sp
Note: The command is equivalent to the command \fBtypemethod\fR
provided by the OO package \fBsnit\fR for the same purpose\&.
.sp
Example
.CS


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

.CE
.TP
\fBclassvariable\fR ?\fIarg\fR\&.\&.\&.?
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\&.
.sp
Note: The command is roughly equivalent to the command
\fBtypevariable\fR provided by the OO package \fBsnit\fR for the
same purpose\&. The difference is that it cannot be used in the class
definition itself\&.
.sp
Example:
.CS


% 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

.CE
.TP
\fBlink\fR \fImethod\fR\&.\&.\&.
.TP
\fBlink\fR {\fIalias\fR \fImethod\fR}\&.\&.\&.
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
\fBmy\fR command\&.
.sp
The alias name under which the method becomes available defaults
to the method name, except where explicitly specified through an
alias/method pair\&.
.sp
Examples:
.CS


    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\&.

.CE
.IP
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\&.
.TP
\fBooutil::singleton\fR ?\fIarg\fR\&.\&.\&.?
This command is a meta-class, i\&.e\&. a variant of the builtin
\fBoo::class\fR which ensures that it creates only a single
instance of the classes defined with it\&.
.sp
Syntax and results are like for \fBoo::class\fR\&.
.sp
Example:
.CS


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

.CE
.PP
.SH AUTHORS
Donal Fellows, Andreas Kupries
.SH "BUGS, IDEAS, FEEDBACK"
This document, and the package it describes, will undoubtedly contain
bugs and other problems\&.
Please report such in the category \fIoo::util\fR of the
\fITcllib Trackers\fR [http://core\&.tcl\&.tk/tcllib/reportlist]\&.
Please also report any ideas for enhancements you may have for either
package and/or documentation\&.
.PP
When proposing code changes, please provide \fIunified diffs\fR,
i\&.e the output of \fBdiff -u\fR\&.
.PP
Note further that \fIattachments\fR are strongly preferred over
inlined patches\&. Attachments can be made by going to the \fBEdit\fR
form of the ticket immediately after its creation, and then using the
left-most button in the secondary navigation bar\&.
.SH "SEE ALSO"
snit(n)
.SH KEYWORDS
TclOO, callback, class methods, class variables, command prefix, currying, method reference, my method, singleton
.SH CATEGORY
Utility
.SH COPYRIGHT
.nf
Copyright (c) 2011-2015 Andreas Kupries, BSD licensed

.fi
