JSTL: remove object from scope

Hi,

I have four objects in four different scopes
[page,request,session,application].

And I use:
<c:remove var="popy"/>

In the absence of the scope attribute it removes the objects from all the
four scopes.

If it is required to remove the object from the session
scope won't <c:remove var="popy"/> be correct answer too, because it
starts from page and goes on goes on, finding and removing objects of that
name from the scopes?

Please confirm this!

Thanks,

No Chandra

Because the requirement is to remove it from session.
Not from all the scopes.

Just imagine of the havoc, it can create in a running application.
If by mistake
instead of writing <c:remove var="popy" scope="session"/>
you write <c:remove var="popy"/>

Objects in the other scopes might being used somewhere else in the application.

So it always better to be specific.

And in exam, I think it will depend on the number of options to be choosen.

Regards,
Khushhal

Thanks khushhal,

Yeah it is was I was looking for! It would depend on how many options
we have to choose, but we should be very specific. Alright!

Thanks,

Chandra,

You are absolutely correct.

Given options
1. <c:remove var="poppy"/>
2. <c:remove var="poppy" scope=session/>

if (asked to select one which will delete poppy from session only) {
then choose 2.
}
else{
if (asked to select two from following which can delete poppy from session) then choose 1,2.
}
[ August 14, 2007: Message edited by: Srinivasan thoyyeti ]

Yeah Srinivasan,

That would be right way to handle with that sort of question.

Your wise description made it more clear!

Thanks,
[ August 14, 2007: Message edited by: Chandra Bhatt ]

Chandra, thank you for your post that pointed out the in the absence of a scope attribute in the <c:remove> tag, the scope is all scopes. On page 448 pf HFSJ it says that the default scope is page. I missed the correction in the errata of the book

{448} 2nd handwritten comment;
The scope is optional, and like always - page is the default scope.
should be:
The scope is optional, and when not specified the attribute is removed from all scopes.

In appreciation of your post, I have written a JSP that points out what you wrote. Here it is

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 
<HTML>
<HEAD>
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
 
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
 
<META http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<META name="GENERATOR" content="IBM Software Development Platform">
<META http-equiv="Content-Style-Type" content="text/css">
<LINK href="theme/Master.css" rel="stylesheet"
type="text/css">
<TITLE>Remove Tag Test</TITLE>
</HEAD>
<BODY>
 
 setting String object into all 4 scopes using same key name 
<c:set var="popy" value=" I am in page scope"></c:set>
<c:set var="popy" scope="request" value=" I am in request scope"></c:set>
<c:set var="popy" scope="session" value=" I am in session scope"></c:set>
<c:set var="popy" scope="application" value=" I am in appliation scope"></c:set>
 
 Where am I? ${popy}
<c:if test="${empty popy}" >popy is nowhere to be found</c:if>
 
 Removing popy from page scope
<c:remove var="popy" scope="page"/>
 
 Where am I? ${popy}
<c:if test="${empty popy}" >popy is nowhere to be found</c:if>
 
 Removing popy from request scope
<c:remove var="popy" scope="request"/>
 
 Where am I? ${popy}
<c:if test="${empty popy}" >popy is nowhere to be found</c:if>
 Removing popy from session scope
<c:remove var="popy" scope="session"/>
 
 Where am I? ${popy}
<c:if test="${empty popy}" >popy is nowhere to be found</c:if>
 Removing popy from application scope
<c:remove var="popy" scope="application"/>
 
 
 Where am I? ${popy}
<c:if test="${empty popy}" >popy is nowhere to be found</c:if>
 starting over... 
 setting String object into all 4 scopes using same key name 
<c:set var="popy" value=" I am in page scope"></c:set>
<c:set var="popy" scope="request" value=" I am in request scope"></c:set>
<c:set var="popy" scope="session" value=" I am in session scope"></c:set>
<c:set var="popy" scope="application" value=" I am in appliation scope"></c:set>
 
 Where am I? ${popy}
<c:if test="${empty popy}" >popy is nowhere to be found</c:if>
 
 Removing popy from page scope
<c:remove var="popy" scope="page"/>
 
 Where am I? ${popy}
<c:if test="${empty popy}" >popy is nowhere to be found</c:if>
 Removing popy again without using a scope
<c:remove var="popy" />
 
 Where am I? ${popy}
 
<c:if test="${empty popy}" >popy is nowhere to be found</c:if>

</BODY>
</HTML>

Once again, thanks

Thank you Michael,

I appreciate you!