Oh an old topics ;)) I understoud the benefits and I just buy a book about JSTL.
Thanks for your clear post Craig. -- Alexandre Jaquet ----- Original Message ----- From: "Craig R. McClanahan" <[EMAIL PROTECTED]> To: "Struts Users Mailing List" <[EMAIL PROTECTED]> Sent: Thursday, March 06, 2003 2:51 AM Subject: RE: [struts-el] What's the benefits ? > > > > From: alexj [mailto:[EMAIL PROTECTED] > > > > I didn't find the benefits of the use of jstl extention. > > > > Who can explain me the benefits ? > > > From: p2 - apache <[EMAIL PROTECTED]> > > > > Some body don't want to see <% .... %>? Just a guess. > > There's lots of advantages to the expression language that Struts-EL uses > (copied from JSTL 1.0, and to be embedded everywhere in a JSP page in JSP > 2.0). My favorite feature is independence from the underlying > implementation of the properties. Consider the following expression: > > ${customer.mailAddress.city} > > This works for all of the following scenarios (as well as some others): > > * "customer" is a bean with a getMailAddress() getter, which in term > returns a bean with a getCity() getter. > > * "customer" is a bean where getMailAddress() returns a Map that has > (among others) an entry with a key of "city". > > * "customer" is a Map that has a key "mailAddress" whose value is a > bean with a getCity() method. > > * "customer" is a Map with a key of "mailAddress" that returns a Map > that has a key of "city" ... > > You get the idea? The business tier developer has a fair amount of > freedom in how they implement the beans representing the data required by > the view tier -- or even skips implementing them if Maps do the trick. > And changing your mind among these choices does not invalidate the syntax > of the expression that is embedded in your page. > > The other thing I like about EL expressions is that the syntax is very > close to what page authors familiar with JavaScript already understand, so > it's natural for them to be able to script with it, without having to know > any java at all. Consider a personnel management app that wants to > restrict the display of salary information to managers. In a JSP 1.2 > environment (with JSTL), you could write: > > <c:if test="${user.role = 'Manager'}"> > <c:out value="${employee.salary}"/> > </c:if> > > and have a fair chance that the page author can understand it -- while the > corresponding scriptlet version is pretty opaque to a non-programmer: > > <% > if (user.getRole().equals("Manager")) { > out.println(employee.getSalary()); > } > %> > > to say nothing of the fact that the Java code requires you to expose > "user" and "employee" as instance variables in the page class, while the > tagged version doesn't. (And, by the way, you'd better be prepared for > NullPointerException errors in the scriptlet, while the expression > language deals with them for you.) > > By the way, in a JSP 2.0 environment, this example will get even simpler: > > <c:if test="${user.role = 'Manager'}"> > ${employee.salary} > </c:if> > > because you will be able to use EL expressions anywhere (including > template text), not just in tags that understand it. > > Craig McClanahan > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
