Beginning Web Development With Perl : From Novice to ... - Nabo

CHAPTER 13 ■ PERL WEB SITES WITH MASON 273Figure 13-5. The modified conditional code in action■Tip In practice, I use either or a single % on each line of code when I have just a few lines toprocess. I find it easier to type % on each line rather than the more formal and , unlessthere’s another reason for using , an example of which you’ll see later.Four additional types of tags are used rather frequently with Mason. These types include to indicate another component call. Consider this akin to a function call; argumentscan be carried with the call. Another type is and , which indicate a block ofcode to be processed before the main page is processed. The and tags areused for code that should run once at component load time, such as the use pragma to importthe DBI into a namespace (use DBI;). A final type of delimiter or markup for Mason is and , which process the arguments being passed into the component.Other types of markup are available with Mason, but the seven tag types described in thissection are the ones you’ll likely encounter right away when getting to know Mason. Table 13-2presents a recap of the seven frequently used Mason delimiters.Table 13-2. Frequently Used Mason DelimitersDelimiterPurpose Evaluate statements and interpolate values inline.% Execute single lines of Perl, conditionals, and loops.Call another component. ... Process incoming arguments to a component. ... Process prior to the main page. ... Process once at component initialization. ... Execute multiple lines of Perl.