Role('JooseX.Attribute.Delegate', {
have : {
handles : null
},
override : {
eachDelegate : function (handles, func, scope) {
if (typeof handles == 'string') return func.call(scope, handles, handles)
if (handles instanceof Array)
return Joose.A.each(handles, function (delegateTo) {
func.call(scope, delegateTo, delegateTo)
})
if (handles == Object(handles))
Joose.O.eachOwn(handles, function (delegateTo, handleAs) {
func.call(scope, handleAs, delegateTo)
})
},
getAccessorsFor : function (targetClass) {
var targetMeta = targetClass.meta
var methods = this.SUPER(targetClass)
var me = this
this.eachDelegate(this.handles, function (handleAs, delegateTo) {
if (!targetMeta.hasMethod(handleAs)) {
var handler = methods[ handleAs ] = function () {
var attrValue = me.getValueFrom(this)
return attrValue[ delegateTo ].apply(attrValue, arguments)
}
handler.ACCESSOR_FROM = me
}
})
return methods
},
getAccessorsFrom : function (from) {
var methods = this.SUPER(from)
var me = this
var targetMeta = from.meta
this.eachDelegate(this.handles, function (handleAs) {
var handler = targetMeta.getMethod(handleAs)
if (handler && handler.value.ACCESSOR_FROM == me) methods.push(handleAs)
})
return methods
}
}
})
/**
Name
====
JooseX.Attribute.Delegate - map a method to the method of the attribute
SYNOPSIS
========
Class('Some.Class', {
has : {
someAttr1 : {
handles : 'commonMethod'
},
// or
someAttr2 : {
handles : [ 'commonMethod1', 'commonMethod2' ]
},
// or
someAttr3 : {
handles : {
classMethod : 'attributeMethod'
}
}
}
})
var instance = new Some.Class()
var a = instance.classMethod('foo', 'bar')
var b = instance.commonMethod('bar', 'baz')
// eqivalent to
var a = instance.someAttr3.attributeMethod('foo', 'bar')
var b = instance.someAttr1.commonMethod('bar', 'baz')
WHAT IS DELEGATION?
===================
Delegation is a feature that lets you create "proxy" methods that do nothing more than call some other method on an attribute.
This is quite handy since it lets you simplify a complex set of "has-a" relationships and present a single unified API from one class.
With delegation, consumers of a class don't need to know about all the objects it contains, reducing the amount of API they need to learn.
Delegations are defined as a mapping between one or more methods provided by the "real" class (the delegatee), and a set of corresponding methods in the delegating class.
The delegating class can re-use the method names provided by the delegatee or provide its own names.
DEFINING A MAPPING
==================
In the simplest form mapping is a string, which corresponds to the proxy method name.
has : {
someAttr : 'method'
}
Its possible to specify an array with the method names:
has : {
someAttr : {
handles : [ 'method1', 'method2' ]
}
}
For each array entry, in the class consuming the attribute, will be created a proxy method. This method will delegate to the method of the attribute with the same name.
Its possible to rename methods during mapping, supplying the mapping value as object:
has : {
someAttr : {
handles : {
proxyMethod : 'methodOfTheAttribute'
}
}
}
SEE ALSO
========
[Main documentation page](../Attribute.html)
AUTHORS
=======
Nickolay Platonov <nplatonov@cpan.org>
COPYRIGHT AND LICENSE
=====================
Copyright (c) 2009, Nickolay Platonov
All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
* Neither the name of Nickolay Platonov nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/;
Role('JooseX.Attribute.Trigger', {
have : {
trigger : null
},
after : {
initialize : function() {
if (this.trigger) this.writeable = this.hasSetter = true
}
},
override : {
getSetter : function() {
var original = this.SUPER()
var trigger = this.trigger
if (!trigger) return original
var me = this
return function () {
var res = original.apply(this, arguments)
trigger.call(this, me.getValueFrom(this))
return res
}
}
}
})
/**
Name
====
JooseX.Attribute.Trigger - call a function after attribute has been changed via setter call
SYNOPSIS
========
Class('Some.Class', {
has : {
someAttribuute : {
init : 'foo',
trigger : function (newValue) {
this.triggerCalled = true
}
}
}
})
var instance = new Some.Class()
instance.triggerCalled == false //trigger wasn't called yet
instance.setSomeAttibute('bar')
instance.triggerCalled == true //trigger was called
DESCRIPTION
===========
`JooseX.Attribute.Trigger` is a role, which triggers a function call, after an attribute was changed via setter call.
It is called as a method (in the scope of the instance), and receives the new value as argument.
Trigger is also called when an attribute's value is passed to the constructor.
**Note**, that trigger will not be called for the value of attribute's `init` option, as it only translates the value to the prototype of the class
SEE ALSO
========
[Main documentation page](../Attribute.html)
AUTHORS
=======
Nickolay Platonov <nplatonov@cpan.org>
COPYRIGHT AND LICENSE
=====================
Copyright (c) 2009, Nickolay Platonov
All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
* Neither the name of Nickolay Platonov nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/;
Role('JooseX.Attribute.Lazy', {
have : {
lazy : null
},
before : {
computeValue : function () {
if (typeof this.init == 'function' && this.lazy) {
this.lazy = this.init
delete this.init
}
}
},
after : {
initialize : function () {
if (this.lazy) this.readable = this.hasGetter = true
}
},
override : {
getGetter : function () {
var original = this.SUPER()
var lazy = this.lazy
if (!lazy) return original
var me = this
return function () {
if (!me.hasValue(this)) {
var initializer = typeof lazy == 'function' ? lazy : this[ lazy.replace(/^this\./, '') ]
me.setValueTo(this, initializer.call(this, me))
}
return original.call(this)
}
}
}
})
/**
Name
====
JooseX.Attribute.Lazy - a role, deferring the attribute initialization untill first call to getter
SYNOPSIS
========
Class('Some.Class', {
has : {
lazyAttribute : {
init : function () {
return this.someCostlyComputation()
},
lazy : true
},
// -or-
lazyAttribute : {
lazy : function () {
return this.someCostlyComputation()
}
},
// -or-
lazyAttribute : {
lazy : 'this.someCostlyComputation'
},
// -or-
lazyAttribute : {
lazy : 'someCostlyComputation'
}
},
methods : {
someCostlyComputation : function () {
...
}
}
})
var instance = new Some.Class()
instance.lazyAttribute == undefined // true, initializer of lazy attribute wasn't called yet
var lazy = instance.getLazyAttibute()
instance.lazyAttribute != undefined // true, initializer of lazy attribute was called
DESCRIPTION
===========
Joose lets you defer attribute population by making an attribute lazy (see the [Synopsis][] for syntax)
When `lazy` flag is set, the default is not generated until the getter method is called, rather than at object construction time.
There are several reasons you might choose to do this.
First, if the default value for this attribute depends on some other attributes, then the attribute must be lazy.
During object construction, defaults are not generated in a predictable order, so you cannot count on some other attribute being populated when generating a default.
Second, there's often no reason to calculate a default before it's needed. Making an attribute lazy lets you defer the cost until the attribute is needed.
If the attribute is never needed, you save some CPU time.
SEE ALSO
========
[Main documentation page](../Attribute.html)
AUTHORS
=======
Nickolay Platonov <nplatonov@cpan.org>
COPYRIGHT AND LICENSE
=====================
Copyright (c) 2009, Nickolay Platonov
All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
* Neither the name of Nickolay Platonov nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
;
Role('JooseX.Attribute.Accessor.Combined', {
have : {
isCombined : false
},
after : {
initialize : function() {
this.isCombined = this.isCombined || /..c/i.test(this.is)
if (this.isCombined) {
this.slot = '$$' + this.name
this.hasGetter = true
this.hasSetter = false
this.setterName = this.getterName = this.publicName
}
}
},
override : {
getGetter : function() {
var getter = this.SUPER()
if (!this.isCombined) return getter
var setter = this.getSetter()
var me = this
return function () {
if (!arguments.length) {
if (me.readable) return getter.call(this)
throw "Call to getter of unreadable attribute: [" + me.name + "]"
}
if (me.writeable) return setter.apply(this, arguments)
throw "Call to setter of read-only attribute: [" + me.name + "]"
}
}
}
})
/**
Name
====
JooseX.Attribute.Accessor.Combined - a role, combining setter and getter methods into one, ala perl
SYNOPSIS
========
Class('Some.Class', {
has : {
attr : {
is : 'rwc',
init : 'some init value'
}
}
})
var instance = new Some.Class()
instance.attr() == 'some init value' // call to combined accessor as getter
instance.attr('some other value') // call to combined accessor as setter
instance.attr() == 'some other value' // attribute was changed
DESCRIPTION
===========
This role combines the getter and setter methods into one, having the same name as attribute itself.
Call this method without arguments will be directed to the actual getter call.
Call with some arguments provided will be directed to setter call.
Its safe to combine this role with Lazy and Trigger, but it should be applied after them.
USAGE
=====
To enable this role provide the trailing `c` character in attribute's `is` option:
has : {
attr : {
is : 'rwc',
init : 'some init value'
}
}
Alternatively, explicitly specify `isCombined` option with some `true` value:
has : {
attr : {
is : 'rw',
isCombined : true,
init : 'some init value'
}
}
SEE ALSO
========
[Main documentation page](../Attribute.html)
AUTHORS
=======
Nickolay Platonov <nplatonov@cpan.org>
COPYRIGHT AND LICENSE
=====================
Copyright (c) 2009, Nickolay Platonov
All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
* Neither the name of Nickolay Platonov nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
;