This page describes an upcoming enhancement to TclOO: Property tracking. Please stay tuned.
The concept: Adding information that is tracked by class that allows the developer to embed data inside of classes
This method allows access to this class. Arguments that follow are the same as allowed by the "dict" command.
There will be an equivalent lookup based on objects.
This method provides objects access to the property database of their class. (Without the hassle of having to look up their class.) At present, it is read only.
The following keywords will be added to oo::define:
Set a property from the class definition.
This system was originally intended to provide a Tk option-like database for TclOO objects.
# Dump the entire option dictionary
set option_dict [info object [self] property get option]
# Access a list of options
set option_list [info object [self] property list option]
# Check if an option exists
set exists [info object [self] property exists option color]
# Get the default value for color
set color [info object [self] property getnull option color default]
oo::define oo::class_withopts {
constructor args {
my InitializePublic {*}$args
}
method InitializePublic args {
my variable config
set optiondict [info object [self] property get option]
# Populate config() with defaults
foreach {field info} $optiondict {
if {[info exists config($field)]} continue
if {[dict exists $optiondict $field]} {
set config($field) [dict get $optiondict default]
} else {
set config($field) {}
}
}
foreach {field value} $args {
set key [string trimleft $key -]
if {![dict exists $optiondict $key]} {
error "Bad option: $key, valid: [lsort -dictionary [dict keys $optiondict]]"
}
set config($field) $value
}
}
method configure args {
my variable config
set triggers {}
set optiondict [info object [self] property get option]
foreach {key value} $args {
set key [string trimleft $key -]
if {![dict exists $optiondict $key]} {
error "Bad option: $key, valid: [lsort -dictionary [dict keys $optiondict]]"
}
}
foreach {key value} $args {
set key [string trimleft $key -]
if {$value != $config($key)} {
set config($key) $value
if {[dict exists $optiondict $field trigger]} {
lappend triggers $field $value [dict get $optiondict $field set-script]
}
}
}
foreach {field value script] $triggers {
eval [string map [list %object% [self] %self% [self] %field% $field %value% $value] $script]
}
}
method cget field {
set field [string trimleft $field -]
if {![info object property [self] exists option $field]} {
error "Invalid option $field, Valid [info option property [self] list option]"
}
my variable config
return $config($field)
}
}