extendscript-reflection-interface
ExtendScript Reflection Interface
ExtendScript provides a reflection interface that allows you to find out everything about an object, including its name, a description, the expected data type for properties, the arguments and return value for methods, and any default values or limitations to the input values.
ReflectionObject
Every object has a reflect property that returns a Reflection Object that reports the contents of the object. You can, for example, show the values of all the properties of an object with code like this:
var f = new File ("myfile");var props = f.reflect.properties;for (var i = 0; i < props.length; i++) { $.writeln('this property ' + props[i].name + ' is ' + f[props[i].name]);}ReflectionObject Attributes
All properties are read only.
description
reflect.description
Description
Short text describing the reflected object, or undefined if no description is available.
Type
String
help
reflect.help
Description
Longer text describing the reflected object more completely, or undefined if no description is available.
Type
String
methods
reflect.methods
Description
An Array of ReflectionInfo object containing all methods of the reflected object, defined in the class or in the specific instance.
Type
Array of ReflectionInfo objects
name
reflect.name
Description
The class name of the reflected object.
Type
String
properties
reflect.properties
Description
An Array of ReflectionInfo object containing all properties of the reflected object, defined in the class or in the specific instance. For objects with dynamic properties (defined at runtime) the list contains only those dynamic properties that have already been accessed by the script.
For example, in an object wrapping an HTML tag, the names of the HTML attributes are determined at run time.
Type
Array of ReflectionInfo objects
ReflectionObject Methods
find()
reflectionObj.find(name)
Description
Returns the ReflectionInfo object for the named property of the reflected object, or null if no such property exists.
Use this method to get information about dynamic properties that have not yet been accessed, but that are known to exist.
Parameters
| Parameter | Type | Description |
|---|---|---|
| name | String | The property for which to retrieve information. |
Examples
This code determines the class name of an object:
obj = new String ("hi");obj.reflect.name; // => StringThis code gets a list of all methods:
obj = new String ("hi");obj.reflect.methods; //=> indexOf,slice,...obj.reflect.find ("indexOf"); // => the method infoThis code gets a list of properties:
Math.reflect.properties; //=> PI,LOG10,...This code gets the data type of a property:
Math.reflect.find ("PI").type; // => numberReflectionInfo Object
This object contains information about a property, a method, or a method argument.
You can access ReflectionInfo objects in a Reflection object’s properties and methods arrays, by name or index:
obj = new String ("hi");obj.reflect.methods[0];obj.reflect.methods["indexOf"];You can access the ReflectionInfo objects for the arguments of a method in the arguments array of the ReflectionInfo object for the method, by index:
obj.reflect.methods["indexOf"].arguments[0];obj.reflect.methods.indexOf.arguments[0];ReflectionInfo Attributes
arguments
obj.reflect.methods[0].arguments
Description
For a reflected method, an array of ReflectionInfo objects describing each method argument.
Type
Array of ReflectionInfo objects
dataType
obj.reflect.methods[0].dataType
Description
The data type of the reflected element.
Type
String. One of:
"boolean""number""string""Classname": The class name of an object. !!! note Class names start with a capital letter. Thus, the valueStringstands for a JavaScript string, while String is a JavaScript String wrapper object.*: Any type. This is the default.nullundefined: Return data type for a function that does not return any value.unknown
defaultValue
obj.reflect.methods[0].defaultValue
Description
The default value for a reflected property or method argument, or undefined if there is no default value, if the property is undefined, or if the element is a method.
Type
Any
description
obj.reflect.methods[0].description
Description
Short text describing the reflected object, or undefined if no description is available.
Type
String
help
obj.reflect.methods[0].help
Description
Longer text describing the reflected object more completely, or undefined if no description is available.
Type
String
isCollection
obj.reflect.methods[0].isCollection
Description
When true, the reflected property or method returns a collection; otherwise, false.
Type
Boolean
max
obj.reflect.methods[0].max
Description
The maximum numeric value for the reflected element, or undefined if there is no maximum or if the element is a method.
Type
Number
min
obj.reflect.methods[0].min
Description
The minimum numeric value for the reflected element, or undefined if there is no minimum or if the element is a method.
Type
Number
name
obj.reflect.methods[0].name
Description
The name of the reflected element. A string, or a number for an array index.
Type
String or Number
type
obj.reflect.methods[0].type
Description
The type of the reflected element.
Type
String. One of:
readonly: A Read only property.readwrite: A read-write property.createonly: A property that is valid only during creation of an object.method: A method.