Re: Do you ever use reflection instead of OO?

From:
Daniel Pitts <newsgroup.spamfilter@virtualinfinity.net>
Newsgroups:
comp.lang.java.programmer
Date:
Sun, 08 Jun 2008 11:54:44 -0700
Message-ID:
<484bba29$0$12705$7836cce5@newsrazor.net>
Lew wrote:

Stefan Ram wrote:

Aaron Fude <aaronfude@gmail.com> writes:

if (hasMethod(obj, "toHTML"))
 print(callMethod(obj), "toHTML"));
else
 print(obj.toString());
The OO alternative would be to create an interface "HTMLable", but the


  Object oriented languages (like Smalltalk or Lisp) do not
  necessarily have the concept of ??interface?? at all. They lack
  Java's static type system and, therefore, they do not need
  interfaces. So, your idea of ??OO?? seems to be restricted to
  Java's interpretation of ??OO??. In Java, reflection is used to
  add some of the dynamics to Java that object-oriented
  languages have right from the start.

  When an object does not have a ??toHTML?? operation, you can not
  use ??toString?? instead because it might evaluate to a string
  like "<" that might result in an HTML document that is not
  well-formed. There is no way to get an HTML representation
  from an object that is not aware of HTML.

  Your code is not object-oriented, but this is not because it
  does not use an interface or because it uses reflection. It is
  not object-oriented because it uses a type-branch instead of
  polymorphism. To implement polymorphism in Java, sometimes an
  interface is used. So this has to do with interfaces only
  indirectly.


Generally, OP, reflection adds complexity to a solution, and reduces
safety.

I don't have enough context about your problem to presume to judge your
solution. Reflection exists as a tool because it is sometimes useful,
more useful than other available solutions. Like many powerful tools,
reflection is subject to abuse, arguably more at risk for worse
consequences than other tricks of the trade.

In the end, the best advice is to reflect responsibly, and don't blame
the knife if you find its edge too sharp.


I've written a bit about reflection.
<http://virtualinfinity.net/wordpress/program-design/2007/01/11/the-dangers-of-reflection-or-put-down-that-mirror/>

My conclusion is that reflection should be used in well tested framework
code, not application/business code.

--
Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>

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