.NET/ASP.NET/C#/VB.NET PDF Document SDK

If you have caught an exception but you want to raise it again (pass it on, so to speak), you can call raise without any arguments. (You can also supply the exception explicitly if you catch it, as explained in the section Catching the Object, later in this chapter.) As an example of how this might be useful, consider a calculator class that has the capability to muffle ZeroDivisionErrors. If this behavior is turned on, the calculator prints out an error message instead of letting the exception propagate. This is useful if the calculator is used in an interactive session with a user, but if it is used internally in a program, raising an exception would be better. Therefore the muffling can be turned off. Here is the code for such a class: class MuffledCalculator: muffled = 0 def calc(self, expr): try: return eval(expr) except ZeroDivisionError: if self.muffled: print 'Division by zero is illegal' else: raise

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Let s use the basic knowledge you ve gathered so far to create your own controller action and view from scratch to show all your diary entries in full on a single page in a diary or blog-style layout.

8

Creating a new method is as easy as adding a method to the controller of your choice. Add the following method to app/controllers/entries_controller.rb:

This code defines a method (and therefore, a controller action) called view_all that contains a single line that retrieves all the entries from your database, ordered in chronologically descending order (like a blog). The order is defined by the optional :order parameter. ActiveRecord methods, such as find, have many useful optional parameters such as these to get the results you desire. You can learn all about them from the official Ruby on Rails documentation, as there are too many to cover here. Now you have an action that will respond when you visit http://localhost/ entries/view_all, but if you try to access that URL, you ll get the following error:

As you explored with your sketches in 7, there are many possible ways you can use layouts to make your set of Key Point slides stand out from the others. One quick and easy way to make these important slides stand out is to apply a split-screen layout to them. To create a custom split-screen layout to apply to your Key Point slides, follow these steps:

The error reminds you that even though you have an action, you don t have a view associated with that action. To create the associated view, you can just create a new file in app/views/entries called view_all.rhtml. Within view_all.rhtml, place this code:

Note If division by zero occurs and muffling is turned on, the calc method will (implicitly) return None.

<% @entries.each do |entry| %> <h1><%= entry.title %></h1> <p><%= entry.content %></p> <p><em>Posted at <%= entry.created_at %></em></p> <% end %> <%= link_to 'Add New entry', :controller => 'entries', :action => 'new' %>

Once this code is in place, you can access http://localhost/entries/view_all successfully, resulting in a page as shown in Figure 13-5.

In the Overview pane, right-click the large Of ce Theme Slide Master slide. When you select any Slide Master in the Overview pane, all of its editable elements appear in the large view of the Slide Master in the slide pane. The Of ce Theme Slide Master determines the formatting of any new Slide Masters and custom layouts you will create. You can adjust the font type, size, and color if you want to apply those changes to all slides going forward, but do not delete anything from this particular Slide Master. When you have nished, in the Overview pane, right-click the Of ce Theme Slide Master, and select Preserve Master. In the Overview pane, position the cursor directly below the Of ce Theme Slide Master slide, and then right-click and choose Insert Layout. Right-click the custom layout you created, choose Rename Layout, and in the Rename Layout dialog box, type Key Point and then click Rename. In the slide pane, right-click the large view of the Slide Master and select Grid And Guides, and in the Grid And Guides dialog box, under Guide Settings, select the Display Drawing Guides On Screen check box, and then click OK. This gives you temporary guides to help align objects on a slide, which you can remove by following the same steps and clearing the check box. See PowerPoint Help to learn more about how to use temporary guides.

Let s take a look at what the code in your new action and view does. When you request http://localhost/entries/view_all, the view_all method in the entries controller is run: