CSC/ECE 517 Fall 2009/wiki2 5 ReflectionApis - Revision history

Object at 21:06, 14 October 2009

2009-10-14T21:06:20Z

← Older revision		Revision as of 21:06, 14 October 2009
Line 2:		Line 2:

	----		----
			<br>
	= Introduction =		= Introduction =

Line 19:		Line 19:
	• Eiffel<br>		• Eiffel<br>

			<br>
	= Is reflection "Built-in"? =		= Is reflection "Built-in"? =

Line 25:		Line 26:
	Languages like C, C++ lack reflective capabilities. They are based on the philosophy of "You don't pay for what you don't use". Maintaining information about types, methods and the like involve significant overhead. Moreover, performance can become a bottleneck, not to mention a few security concerns with reflection. C and C++ compilers optimize code to maximize performance and are not open to trade performance and overhead. If reflection is deemed necessary for such languages, there would have to be another library or a tool to take care of parsing the source code, building abstract syntax trees containing every detail of the program, build symbol tables, extract control and data flows by building a graphical representation and have custom analysers analyse this representation. The DMS Software Reengineering Toolkit is one such toolkit for C, C++ and COBOL.		Languages like C, C++ lack reflective capabilities. They are based on the philosophy of "You don't pay for what you don't use". Maintaining information about types, methods and the like involve significant overhead. Moreover, performance can become a bottleneck, not to mention a few security concerns with reflection. C and C++ compilers optimize code to maximize performance and are not open to trade performance and overhead. If reflection is deemed necessary for such languages, there would have to be another library or a tool to take care of parsing the source code, building abstract syntax trees containing every detail of the program, build symbol tables, extract control and data flows by building a graphical representation and have custom analysers analyse this representation. The DMS Software Reengineering Toolkit is one such toolkit for C, C++ and COBOL.

			<br><br>
	= Programming Language APIs =		= Programming Language APIs =

Line 158:		Line 160:

	In many ways, the support for reflection in Ruby and Python is similar. The syntax obviously differs and a detailed list and explanation of these can be found here[http://diveintopython.org/power_of_introspection/lambda_functions.html#d0e10403]		In many ways, the support for reflection in Ruby and Python is similar. The syntax obviously differs and a detailed list and explanation of these can be found here[http://diveintopython.org/power_of_introspection/lambda_functions.html#d0e10403]
			<br>
	= Conclusion =		= Conclusion =
	Reflection can be extremely powerful when used in the right amounts. Although language like Java and C# are verbose, they have good support for reflection. Ruby and Python being dynamically typed work wondefully well and are simpler to use. One major drawback of using reflection in java or C# is that the virtual machine starts interpreting code. This considerably slows down performance. The second drawback of reflection is wrt obscuring the code. Using too much of reflection can make the code obscure to the reader. If reflection is harvested in the right amounts, it can make the design more extensible while at the same time reducing programming overhead. Dynamically typed languages like Ruby and Python have simpler APIs and are hence easier to use		Reflection can be extremely powerful when used in the right amounts. Although language like Java and C# are verbose, they have good support for reflection. Ruby and Python being dynamically typed work wondefully well and are simpler to use. One major drawback of using reflection in java or C# is that the virtual machine starts interpreting code. This considerably slows down performance. The second drawback of reflection is wrt obscuring the code. Using too much of reflection can make the code obscure to the reader. If reflection is harvested in the right amounts, it can make the design more extensible while at the same time reducing programming overhead. Dynamically typed languages like Ruby and Python have simpler APIs and are hence easier to use

Object: /* Conclusion */

2009-10-14T20:56:10Z

Conclusion

← Older revision		Revision as of 20:56, 14 October 2009
Line 160:		Line 160:

	= Conclusion =		= Conclusion =
	Reflection can be extremely powerful when used in the right amounts. Although language like Java and C# are verbose, they have good support for reflection. Ruby and Python being dynamically typed work wondefully well and are simpler to use. One major drawback of using reflection in java or C# is that the virtual machine starts interpreting code. This ~~conisderably~~ slows down performance. The second drawback of reflection is wrt obscuring the code. Using too much of reflection can make the code obscure to the reader. If reflection is harvested in the right amounts, it can make the design more extensible while at the same time reducing programming overhead. Dynamically typed languages like Ruby and Python have simpler APIs and are hence easier to use		Reflection can be extremely powerful when used in the right amounts. Although language like Java and C# are verbose, they have good support for reflection. Ruby and Python being dynamically typed work wondefully well and are simpler to use. One major drawback of using reflection in java or C# is that the virtual machine starts interpreting code. This considerably slows down performance. The second drawback of reflection is wrt obscuring the code. Using too much of reflection can make the code obscure to the reader. If reflection is harvested in the right amounts, it can make the design more extensible while at the same time reducing programming overhead. Dynamically typed languages like Ruby and Python have simpler APIs and are hence easier to use

	= See also =		= See also =
	This section lists more resources that can be looked into for advanced reflection concepts in various languages		This section lists more resources that can be looked into for advanced reflection concepts in various languages

Object: /* Ruby */

2009-10-14T20:54:15Z

Ruby

← Older revision		Revision as of 20:54, 14 October 2009
Line 121:		Line 121:
	>> Fixnum, Integer, Precision, Numeric, Comparable, Object, Kernel		>> Fixnum, Integer, Precision, Numeric, Comparable, Object, Kernel

	Ruby can also separately extract private, protected and public methods. An API also exists to extract a singleton method. An example to illustrate this for a class called Demo is shown below. This example is ~~borrowd~~ from RubyCentral.		Ruby can also separately extract private, protected and public methods. An API also exists to extract a singleton method. An example to illustrate this for a class called Demo is shown below. This example is borrowed from RubyCentral.

	private		private

Object: /* Ruby */

2009-10-14T20:53:51Z

Ruby

← Older revision		Revision as of 20:53, 14 October 2009
Line 115:		Line 115:

	== Ruby ==		== Ruby ==
	Dynamic languages like ruby have the ability to introspect - i.e examine snippets of the program within the program itself. While Java and C# call this reflection, Ruby calls it introspection. There is not a big difference in ruby ~~wrt~~ compile time or run-time. Code can be ynamically added to a running process. Thus, unlike Java or C#, there is no observable affect in performance.		Dynamic languages like ruby have the ability to introspect - i.e examine snippets of the program within the program itself. While Java and C# call this reflection, Ruby calls it introspection. There is not a big difference in ruby with respect to compile time or run-time. Code can be ynamically added to a running process. Thus, unlike Java or C#, there is no observable affect in performance.

	Ruby can list all the methods in an object or even check whether an object responds to a particular method using the respond_to? API call. Similarly looking at class hierarchies is extremely simple - .superclass and .ancestors list the hierarchy. Fixnum.ancestors produces the following output:		Ruby can list all the methods in an object or even check whether an object responds to a particular method using the respond_to? API call. Similarly looking at class hierarchies is extremely simple - .superclass and .ancestors list the hierarchy. Fixnum.ancestors produces the following output:

Object: /* Reflective Languages */

2009-10-14T20:53:15Z

Reflective Languages

← Older revision		Revision as of 20:53, 14 October 2009
Line 10:		Line 10:

	= Reflective Languages =		= Reflective Languages =
	The concept of reflective programming was started late back in the 80's. Since then, there have been many languages that provide reflection capabilities. Reflection requires dynamic modification of the program. For this reason, compilers would have to have some metadata format to ~~lok~~ back at it's own code. Java and C# do this through the Java virtual machine and the .NET VM respectively. On the other hand, since dynamic languages like Python and Ruby only try to interpret the code at run-time, more powerful forms of reflection can be achieved. Other languages like C, C++ lack reflection capabilities largely because of the metadata that they fail to maintain. The following are a few languages that support reflection:		The concept of reflective programming was started late back in the 80's. Since then, there have been many languages that provide reflection capabilities. Reflection requires dynamic modification of the program. For this reason, compilers would have to have some metadata format to look back at it's own code. Java and C# do this through the Java virtual machine and the .NET VM respectively. On the other hand, since dynamic languages like Python and Ruby only try to interpret the code at run-time, more powerful forms of reflection can be achieved. Other languages like C, C++ lack reflection capabilities largely because of the metadata that they fail to maintain. The following are a few languages that support reflection:

	• Java<br>		• Java<br>
Line 18:		Line 18:
	• Python<br>		• Python<br>
	• Eiffel<br>		• Eiffel<br>


	= Is reflection "Built-in"? =		= Is reflection "Built-in"? =

Object at 20:52, 14 October 2009

2009-10-14T20:52:51Z

← Older revision		Revision as of 20:52, 14 October 2009
Line 7:		Line 7:
	Reflection is a programming technique used to build code that is flexible by giving the programmer the power to modify and examine the behaviour of a program at runtime. Reflection gives the code access to internal structures of classes - constructors, fields and methods. It falls under the broad area of Metaprogramming - programs that write other programs.Reflection can be very powerful for late binding, creating new types duing run-time, examining types etc.		Reflection is a programming technique used to build code that is flexible by giving the programmer the power to modify and examine the behaviour of a program at runtime. Reflection gives the code access to internal structures of classes - constructors, fields and methods. It falls under the broad area of Metaprogramming - programs that write other programs.Reflection can be very powerful for late binding, creating new types duing run-time, examining types etc.

	This wiki will walk you through the facilities provided by specific languages for using reflection. It does NOT list every API in the language. It answers the following questions: Is reflection "built in" to some ~~o-o~~ languages or do languages require external libraries to perform reflection? What built-in and library functions are provided? Which APIs are easiest to use and why?.		This wiki will walk you through the facilities provided by specific languages for using reflection. It does NOT list every API in the language. It answers the following questions: Is reflection "built in" to some object oriented languages or do languages require external libraries to perform reflection? What built-in and library functions are provided? Which APIs are easiest to use and why?.

	= Reflective Languages =		= Reflective Languages =
Line 24:		Line 24:
	Reflection naturally comes to interpreted languages. Ruby, Python, Smalltalk would not have to go out of their usual way to implement and exhibit reflective properties. On the other hand, Java and .NET look at the intermediate code to figure out the structure of a class and then try to add more at run-time. This, obviously takes a performance hit since the code cannot be compiled and optimized. Java and Microsoft .NET both have references to objects as well as built-in types. Wrappers for built-in types exist that provide reflection on primitive types.		Reflection naturally comes to interpreted languages. Ruby, Python, Smalltalk would not have to go out of their usual way to implement and exhibit reflective properties. On the other hand, Java and .NET look at the intermediate code to figure out the structure of a class and then try to add more at run-time. This, obviously takes a performance hit since the code cannot be compiled and optimized. Java and Microsoft .NET both have references to objects as well as built-in types. Wrappers for built-in types exist that provide reflection on primitive types.

	Languages like C, C++ lack reflective capabilities. They are based on the philosophy of "You don't pay for what you do't use". Maintaining information about types, methods and the like involve significant overhead. Moreover, performance can become a bottleneck, not to mention a few security concerns with reflection. C and C++ compilers optimize code to maximize performance and are not open to trade performance and overhead. If reflection is deemed necessary for such languages, there would have to be another library or a tool to take care of parsing the source code, building abstract syntax trees containing every detail of the program, build symbol tables, extract control and data flows by building a graphical representation and have custom analysers analyse this representation. The DMS Software Reengineering Toolkit is one such toolkit for C, C++ and COBOL.		Languages like C, C++ lack reflective capabilities. They are based on the philosophy of "You don't pay for what you don't use". Maintaining information about types, methods and the like involve significant overhead. Moreover, performance can become a bottleneck, not to mention a few security concerns with reflection. C and C++ compilers optimize code to maximize performance and are not open to trade performance and overhead. If reflection is deemed necessary for such languages, there would have to be another library or a tool to take care of parsing the source code, building abstract syntax trees containing every detail of the program, build symbol tables, extract control and data flows by building a graphical representation and have custom analysers analyse this representation. The DMS Software Reengineering Toolkit is one such toolkit for C, C++ and COBOL.

	= Programming Language APIs =		= Programming Language APIs =

Object at 04:47, 11 October 2009

2009-10-11T04:47:50Z

← Older revision		Revision as of 04:47, 11 October 2009
Line 1:		Line 1:
	<b> Reflection APIs</b>		<b> Reflection APIs </b>

	----		----
Line 22:		Line 22:
	= Is reflection "Built-in"? =		= Is reflection "Built-in"? =

	Reflection naturally comes to interpreted languages. Ruby, Python, Smalltalk would not have to go out of their usual way to implement and exhibit reflective properties. On the other hand, Java and .NET look at the intermediate code to figure out the structure of a class and then try to add more at run-time. This, obviously takes a performance hit since the code cannot be compiled and optimized. Java and .NET both have references to objects as well as built-in types. Wrappers for built-in types exist that provide reflection on primitive types.		Reflection naturally comes to interpreted languages. Ruby, Python, Smalltalk would not have to go out of their usual way to implement and exhibit reflective properties. On the other hand, Java and .NET look at the intermediate code to figure out the structure of a class and then try to add more at run-time. This, obviously takes a performance hit since the code cannot be compiled and optimized. Java and Microsoft .NET both have references to objects as well as built-in types. Wrappers for built-in types exist that provide reflection on primitive types.

	Languages like C, C++ lack reflective capabilities. They are based on the philosophy of "You don't pay for what you do't use". Maintaining information about types, methods and the like involve significant overhead. Moreover, performance can become a bottleneck, not to mention a few security concerns with reflection. C and C++ compilers optimize code to maximize performance and are not open to trade performance and overhead. If reflection is deemed necessary for such languages, there would have to be another library or a tool to take care of parsing the source code, building abstract syntax trees containing every detail of the program, build symbol tables, extract control and data flows by building a graphical representation and have custom analysers analyse this representation. The DMS Software Reengineering Toolkit is one such toolkit for C, C++ and COBOL.		Languages like C, C++ lack reflective capabilities. They are based on the philosophy of "You don't pay for what you do't use". Maintaining information about types, methods and the like involve significant overhead. Moreover, performance can become a bottleneck, not to mention a few security concerns with reflection. C and C++ compilers optimize code to maximize performance and are not open to trade performance and overhead. If reflection is deemed necessary for such languages, there would have to be another library or a tool to take care of parsing the source code, building abstract syntax trees containing every detail of the program, build symbol tables, extract control and data flows by building a graphical representation and have custom analysers analyse this representation. The DMS Software Reengineering Toolkit is one such toolkit for C, C++ and COBOL.

Sganaga: /* Java */

2009-10-10T00:39:55Z

Java

← Older revision		Revision as of 00:39, 10 October 2009
Line 83:		Line 83:

	•getSuperClass()     : To return the classes' super class<br>		•getSuperClass()     : To return the classes' super class<br>
	bull;getClasses() ;          : Return all members including inherited members<br>		•getClasses() ;          : Return all members including inherited members<br>
	•getEnclosingClass() : used in case of nested classes. Returns the immediate enclosing <br><br>		•getEnclosingClass() : used in case of nested classes. Returns the immediate enclosing <br><br>

Sganaga: /* Java */

2009-10-10T00:38:57Z

Java

← Older revision		Revision as of 00:38, 10 October 2009
Line 83:		Line 83:

	•getSuperClass()     : To return the classes' super class<br>		•getSuperClass()     : To return the classes' super class<br>
	~~•getClasses()~~        : Return all members including inherited members<br>		bull;getClasses() ;          : Return all members including inherited members<br>
	•getEnclosingClass() : used in case of nested classes. Returns the immediate enclosing <br><br>		•getEnclosingClass() : used in case of nested classes. Returns the immediate enclosing <br><br>

Sganaga: /* Java */

2009-10-10T00:38:05Z

Java

← Older revision		Revision as of 00:38, 10 October 2009
Line 83:		Line 83:

	•getSuperClass()     : To return the classes' super class<br>		•getSuperClass()     : To return the classes' super class<br>
	•getClasses()        : Return all members including inherited members<br>		•getClasses()        : Return all members including inherited members<br>
	•getEnclosingClass() : used in case of nested classes. Returns the immediate enclosing <br><br>		•getEnclosingClass() : used in case of nested classes. Returns the immediate enclosing <br><br>