15: Linguistic Reflection

Question 1

what is linguistic reflection?

Answer 1

Linguistic reflection is the ability of a running
program to generate new program fragments and
to integrate these into its own execution
• Allow a program’s behaviour to adjust dynamically
in order to provide flexibility and high productivity.

Question 2

what is marshalling?

Answer 2

Marshalling is converting the data present in an
object into an xml format and viewing it in an xml
format and unmarshalling is reverse of it
converting an xml file into an object.

Question 3

why is linguistic reflection useful?

Answer 3

If we had access to an object's interface, and we
could generate calls on the fly, we could do lots of
interesting things
o Create a method
call on the fly
o Call code we
weren’t able to
call before
• Re-structure the way
code interacts by allowing method calls to be
decided upon and created at run-time
When we load code dynamically
o Find out the interface to the code
o Make calls on that interface
• When we want to dynamically “wrap” code
o Create facades to existing classes
o Code sees a different interface
o ...or the same interface with
different behaviour
• Create in a uniform way using
tools, rather than by hand

Reflection provides a way to access the meta-level
of a language
• Create dynamic skeletons for components

Question 4

Benefits & Applications?

Answer 4

System evolution
o Load new objects/components without re-compiling
o Extend or replace functionality of a running system
o No loss of type-safety: you still can’t ever call a
method on an object that doesn’t implement it
• Code interaction
o Build a GUI that shows the code (IDEs)
o Allow interactive method calls from a user interface
(Debuggers)
o Unit Testing, Code Coverage, Dependency Injection,
Object Relational Mapping, and much more…