My biggest reservation with placing constants in a map is that it do compile time checking. I suppose it is very important for sites with thousands of JSP files to do precompiling on them. Compiling would fail if the constant is missing. With placing constants in a map, the problem can only be found during runtime which is not ideal in my opinion.
I know many people balk at using expression notation (<%= %>), but if you use JSP documents, you can at least write <jsp:expression>...</jsp:expression> tags and keep your file fully XML compliant (and it looks nicer too!). Thanks, Paul -----Original Message----- From: Matt Raible [mailto:[EMAIL PROTECTED] Sent: Monday, March 21, 2005 12:24 PM To: Struts Users Mailing List Subject: Re: Using constants in JSP pages I wrote a tag library to expose contants to a JSP page. Granted, it's not as portable as HashMap in the app context, but it seems to work. http://raibledesigns.com/wiki/Wiki.jsp?page=ConstantsTag Matt On Mar 21, 2005, at 8:27 AM, Marsh-Bourdon, Christopher wrote: > Agreed, but with my fluff most ides (Eclipse, JBuilder etc) will parse > and > throw an exception/error if the ... in <%= ... %> is undeclared or > there is > a typo there. That at least gives David the answer (albeit a bit of > hash) > David was after. > > Cheers > > Christopher Marsh-Bourdon > www.marsh-bourdon.com > > -----Original Message----- > From: Haroon Rafique [mailto:[EMAIL PROTECTED] > Sent: 21 March 2005 15:20 > To: Struts Users Mailing List > Subject: RE: Using constants in JSP pages > > > On Today at 2:24pm, MC=>Marsh-Bourdon, Christopher > <Christopher.Marsh-Bourd...: > > MC> This is my way of doing this, and it may be a tad crap. In the > page > MC> tag at the top of the JSP I add one or more imports like so: > MC> > MC> <%@ page language="java" import="com.marsh-bourdon.Constants" %> > MC> > MC> I then just refer to the constants within the page like so: > MC> > MC> <%= Constants.KEY_FOR_SOMETHING %> > MC> > MC> This should then be checked by your ide for typos etc. > MC> > MC> Cheers > MC> > MC> Christopher Marsh-Bourdon > MC> www.marsh-bourdon.com > MC> > > Hi David, Christopher, > > I'm sure other people will pipe in shortly, but a variation of this has > been discussed in the mailing list before. From the archives: > http://www.mail-archive.com/user@struts.apache.org/msg06778.html > > In a nutshell: > > 1) Provide a method in your Constants file which puts all your > Constants > in a Map > 2) At app startup make that map available to the application (e.g., in > the > context > 3) Use JSTL, to now access your constants directly without scriptlets. > > David, from your original email, I'm sure you could figure out a naming > scheme to put constants from foo package and bar package under > different > names in the context (like Constants_foo and Constants_bar, etc). That > should achieve 1). > > To achieve 2), you could possibly use the following <c:out> construct. > > <c:out value="${Constants_foo.FOO}"> > <span style="color: red"> > <fmt:message key="undefined.constant"/> > </span> > </c:out> > > Since you're talking about JSP pages, I'm not at all sure how you can > get > the compiler to spot mistakes. But with the above JSTL, you could, at > least, see it in a visible manner on the JSP page that an undefined > constant was used. > > Hope this was helpful. > > Cheers, > > MC> -----Original Message----- > MC> From: David Kennedy [mailto:[EMAIL PROTECTED] > MC> Sent: 21 March 2005 14:18 > MC> To: Struts Users Mailing List > MC> Subject: Using constants in JSP pages > MC> > MC> > MC> Most of our pages have a header/navbar which performs some > highlighting > MC> of the current page's category etc. This means all pages must > define > MC> beans to say things like, "My category is FOO, my sub-category is > BAR" > MC> > MC> I would like to get the compiler to spot typos: > MC> (1) To make sure FOO matches one of the defined categories in the > navbar. > MC> (2) To make sure the category variable itself is correct. > MC> > MC> I can achieve (1) by defining a simple constants class and using > the > MC> 'unstandard' taglib: > MC> <un: var="foo" type="com.foo.Constants" field="FOO"/> > MC> > MC> How can I achieve (2)? A little paranoid I know, but I've already > MC> defined "fo" by mistake in a couple of places(*), and there > doesn't seem > > MC> to be any advantage to using a constant if it is in turn defined by > MC> another hand-typed variable! > MC> > MC> All I can think of is > MC> <un: var="<%=com.foo.Constants.FOO_NAME%>" type="..." field="..."> > MC> but if I'm going to use <%= %> I might as well just write > MC> <%= com.foo.Constants.FOO %> > MC> rather than use bind at all! > MC> > MC> (*) Where obviously the real var names are longer and easier to > typo > MC> than foo. > MC> > > -- > Haroon Rafique > <[EMAIL PROTECTED]> > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > > ----------------------------------------------------------------------- > --------- > The information contained herein is confidential and is intended > solely for the > addressee. 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