CSC/ECE 517 Fall 2009/wiki2 5 jdf: Difference between revisions
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== Languages that Provide a Reflection API == | == Languages that Provide a Reflection API == | ||
Among the languages that provide | Among the languages that provide Reflection APIs we count the following: | ||
* Ruby | |||
* Microsoft .NET, includes C#, C++, and VB.NET | * Microsoft .NET, includes C#, C++, and VB.NET | ||
* Java | * Java | ||
* Smalltalk-80 | * Smalltalk-80 | ||
| Line 33: | Line 33: | ||
Reflection is built into Ruby, it is a standard feature of the language. Objects in Ruby support reflection by default, hence it is not necessary to use any external or additional libraries. | Reflection is built into Ruby, it is a standard feature of the language. Objects in Ruby support reflection by default, hence it is not necessary to use any external or additional libraries. | ||
The following Ruby code will display the class type of a variable: | |||
<pre> | <pre> | ||
| Line 41: | Line 41: | ||
mystr.class | mystr.class | ||
</pre> | |||
The following code displays the class methods: | |||
<pre> | |||
mystr.methods | |||
</pre> | </pre> | ||
Revision as of 01:30, 10 October 2009
Please note that this is still work in progress - Not Yet Ready for Review
Reflection is widely used in programming languages. This topic is not about reflection per se, but about reflection APIs--the facilities that particular languages provide for doing reflection. Is reflection "built in" to some o-o languages, while others require external libraries to perform reflection? What built-in and library functions are provided? Which APIs are easiest to use and why?
Reflection APIs
Introduction
Reflection is a feature offered by many modern programming languages. Reflection provides programmers with the ability to write code that determines information about a set of code during run time. The information that is acquired through reflection can be used to develop very sophisticated program features. Programs can be written to adapt based on the characteristics of the code itself. The information that can be obtained via reflection includes elements such as:
- The class types of objects that are present in the running program
- The class hierarchy of an object or set of objects
- The attributes and methods of objects
- Details of the method calls supported by objects [1]
Reflection is present in many programming languages and its use is particularly prevalent in object oriented languages, such as Java and Ruby. The level of implementation and ease of use varies among languages. The objective of this article is to provide an overview of the different Application Programming Interfaces or APIs that exist in various Object Oriented Languages to provide reflection functionality.
Languages that Provide a Reflection API
Among the languages that provide Reflection APIs we count the following:
- Ruby
- Microsoft .NET, includes C#, C++, and VB.NET
- Java
- Smalltalk-80
Reflection in Ruby
Reflection is built into Ruby, it is a standard feature of the language. Objects in Ruby support reflection by default, hence it is not necessary to use any external or additional libraries.
The following Ruby code will display the class type of a variable:
mystr = "Hello Ruby!" mystr.class
The following code displays the class methods:
mystr.methods
Resources
References
[1] Thomas, D., Fowler C. and Hunt A. Programming Ruby, The Pragmatic Programmer's Guide. 2nd Edition. The Pragmatic Bookshelf.
[2] Help and documentation for the Ruby programming language, RUBY-DOC.ORG
CSC 517 Fall 2009
Wiki 2 Assignment
Author: Newwolf