title | layout | category |
---|---|---|
Invokers |
default |
Infusion |
The public and implementation functions on your component ("methods", in OO terminology) are defined by configuration representing invokers.
Invokers can bind free functions, IoC resolved functions, and
this
based functions to the component, and to the context of the component. Invokers allow the
signature received in the bound function to differ from the signature sent by the caller.
As well as allowing the traditional OO facility for shifting the that
argument
representing the component itself in and out of the argument list, this also allows for much
more powerful reuse of existing functions where signature elements can be sourced freely from
around the component tree and within the original argument list.
An invoker can specified with either the funcName
property to reference a free function by its
global name (e.g. fluid.copy
, fluid.log
, etc.) or the func
property to reference an existing
function (perhaps another invoker) from elsewhere in the component tree.
Property | Description |
---|---|
funcName or func
|
Required type: string funcName - A string representing the name of a free function.func - A string representing an IoC reference to a function which is
attached to the component tree
|
args |
Optional type: array An array of arguments to be passed into the function specified by the func or funcName property. The
values in the array can be of any type, including IoC references. In this context, you may also use
references of the form {arguments}.n , where n is an integer indexing from 0 which refers
to the position of the originating argument, to use arguments passed in when the invoker is called.
If no args are specified, all of the arguments passed into the invoker are sent to the underlying
function unchanged.
|
The following skeleton example defines an invoker named invokerName attached to a component of
type component.name. When a component of the type is instantiated, for example with a line such
as var that = component.name();
, the invoker will then be available as a function directly
attached to the instance, callable under the name invokerName
- e.g. as
that.invokerName(...args...)
fluid.defaults("component.name", {
...
invokers: {
invokerName: {
funcName: <fully namespaced string name of function>,
args: <array of arguments>
},
...
}
...
});
Example:
The following example defines a component of type xyz.widget
, with two invokers named addTwo
and subtractTwo
- the former binds onto a free function named xyz.widget.add
, the latter binds
onto another invoker elsewhere in the tree, which is not shown. Note that there is no necessary
relationship between the name of a component and the name of a free function which is bound to it.
If there is a close relationship between the purpose of a function and a related component, it is
a helpful convention to prefix its name with the component name, as here - however, any free
function may be bound via its global name to any component.
fluid.defaults("xyz.widget", {
...
invokers: {
addTwo: {
funcName: "xyz.widget.add",
args: [2, "{arguments}.0"]
},
subtractTwo: {
func: "{parent}.subtract",
args: ["{arguments}.0", 2],
}
}
...
});
xyz.widget.add = function (a, b) {return a + b;};
Alternatively, invokers can be specified in a compact single line format. However, arguments specified in the invoker can only be strings or IoC References. Strings which can be converted into Numbers or Booleans will be so converted before being interpreted.
fluid.defaults("component.name", {
...
invokers: {
invokerName: "<fully namespaced string name of function>(<comma-separated ioc references>)"
},
...
}
...
});
Example:
fluid.defaults("xyz.widget", {
...
invokers: {
addVal: "xyz.widget.add({that}.staticVal, {arguments}.0)",
subtractVal: "{parent}.subtract({arguments}.0, {that}.staticVal)"
}
...
});
xyz.widget.add = function (a, b) {return a + b;};
Example:
fluid.defaults("fluid.uploader.fileQueue", {
...
invokers: {
start: {
funcName: "fluid.uploader.fileQueue.start",
args: "{that}"
},
startFile: {
funcName: "fluid.uploader.fileQueue.startFile",
args: "{that}.currentBatch"
},
...
},
...
}
If the invoker's record contains the field changePath (rather than the standard func
/funcName
)
this is recognised as a special type of invoker triggering a change to a particular component's
model via its ChangeApplier. This type of record is documented in its own
section with the ChangeApplier API. The compact syntax may not be used with
this variety of record.
Specifying an invoker with a "this"
property allows the invocation of functions whose body
makes a reference to the special JavaScript value "this"
. These are generally functions external
to the Infusion framework such as console.log
, since it is a Fluid community standard to write "that"-ist functions
whose execution is independent of the calling context. These can be any functions, but will most
often be used for jQuery methods. See Declarative this-ism in IoC
for more details. Note that the string this
must always be quoted when appearing as a key as it is
a JavaScript keyword.
Property | Description |
---|---|
"this" |
Required type: object
The object used referenced by "this" internally in the function. For a jQuery method, this is usually an jQuery element.
|
method |
Required type: string The name of the "thisist" function (attached to the this object designated above) to call.
|
args |
Optional type: array An array of arguments to be passed into the function specified by the func or funcName property. The
values in the array can be of any type, including IoC references. In this
context, you may also use references of the form {arguments}.n , where n is an integer
indexing from 0 which refers to the position of the originating argument, to use arguments passed
in when the invoker is called. If no args are specified, all of the arguments passed into the invoker
are sent to the underlying function unchanged. Identical to role in func/funcName style
invokers.
|
fluid.defaults("component.name", {
...
invokers: {
invokerName: {
"this": <reference to an object>,
method: <string name of method on the object>,
args: <array of arguments>
}
}
...
});
Example:
fluid.defaults("xyz.widget", {
...
invokers: {
setAriaLabel: {
"this": "{that}.dom.elm",
method: "attr",
args: ["aria-label", "{arguments}.0"]
}
}
...
});
Example:
fluid.defaults("fluid.uploader.html5Strategy.browseButtonView", {
...
invokers: {
...
disable: {
"this": "{that}.dom.fileInputs",
method: "prop",
args: ["disabled", true]
}
...
},
...
}
"this"-ist invokers have no equivalent compact syntax.