MSDN Magazine - December 2008 - (Page 64)

The following code shows how to get the range that corresponds to the start of the document, using the raw PIA approach: object startPosition = 0; object endPosition = 0; Word.Range r = (Word.Range)doc.Range(ref startPosition, ref endPosition); One of the simplest features provided by the extensions is an overload of the Range method that takes two simple parameters which do not need to be passed by reference. Using the extensions, the call to get the start of the document is far simpler. In this example, the extensions avoid the need to pass the parameters by reference—and they also enforce the requirement to pass strongly typed parameters. The start and end position will always be integers, but the Word object model only specifies that they are loosely typed objects. The extensions impose strong typing on the method signature, which therefore brings the benefits of designtime IntelliSense and compile-time type-checking. It also reduces the code from three lines to one: Word.Range r = doc.Range(0, 0); object to use the default value for the missing parameter. C# does not perform this operation for you. This is another area where the extensions take care of the underlying operation and provide C# developers with an experience that is very similar to the experience of using Visual Basic. For example, to move to the end of the document and paste something in from the Clipboard, code using the raw PIAs must pass any missing parameters explicitly as System.Type.Missing: object gotoItem = Word.WdGoToItem.wdGoToLine; object gotoDirection = Word.WdGoToDirection.wdGoToLast; object missing = Type.Missing; r = r.GoTo(ref gotoItem, ref gotoDirection, ref missing, ref missing); r.Paste(); Another minor inconvenience in the Office object models is the use of parameterized properties. It is common in Office to expose properties that take parameters. Bear in mind that all properties exposed from COM servers are really methods. Methods, of course, can take multiple parameters. In C#, although methods can take parameters, properties cannot. For this reason, the Office PIAs expose parameterized prop- Using the extensions, on the other hand, we can use the objectinitializers feature introduced in C# 3.0 to provide strongly typed named parameters for the values we want to specify and to completely omit any parameters for which we want to use default values. The use of named parameters is another feature that brings a Visual Basic experience to C# developers: r = r.GoTo( new DocumentGoToArgs { What = Word.WdGoToItem.wdGoToLine, Which = Word.WdGoToDirection.wdGoToLast }); r.Paste(); You can search, filter, and query Outlook items using the DASL query language. erties in C# as a pair of get_ and set_ methods. For example, the PIA code to set the style property requires you to pass an object parameter (and by reference again). The following raw PIA code continues on from the previous snippet: here we insert some text after the current Range and set its style: r.InsertAfter("Email Send Time vs Size"); r.InsertParagraphAfter(); r = (Word.Range)doc.Paragraphs[1].Range; object style = Word.WdBuiltinStyle.wdStyleTitle; r.set_Style(ref style); The usefulness of the optional parameter feature in the extensions becomes more obvious with a method like Document.SaveAs in Word. Using PIA code, you need to supply all 16 parameters. In our example, we want to save the document as an HTML file, which requires us to specify the file name and the enum value for HTML file format in Word, both as loosely typed objects. We don’t care about the remaining 14 parameters, but we have to pass them anyway, and we have to pass all parameters by reference: object saveFormat = Word.WdSaveFormat.wdFormatHTML; doc.SaveAs(ref fileName, ref saveFormat, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing); The extension method again uses strong typing and allows us to completely omit optional parameters: doc.SaveAs(fileName, Word.WdSaveFormat.wdFormatHTML); Excel Extensions To do the same thing using the extensions, the code is far more intuitive. As before, it uses strongly typed parameters and a simple method call, without the need for an interim variable and without the set_ or get_ prefix: r.InsertAfter("Email Send Time vs Size"); r.InsertParagraphAfter(); r = (Word.Range)doc.Paragraphs[1].Range; r.Style(Word.WdBuiltinStyle.wdStyleTitle); In the example solution, we use Excel to put a chart into the Clipboard so that we can subsequently paste it into the Word document. First, we get hold of the first worksheet in the workbook. It is common in the Office object models to return specific objects typed as generic objects. For example, the Sheets collection may contain both Worksheet objects and Chart objects, so when you specify a particular item in the collection, the Excel PIA returns it to you as a generic object, which you then need to cast to the specific Sheet type you are expecting: Excel.Worksheet sheet = (Excel.Worksheet)book.Sheets[1]; Many methods in the Office object models take optional parameters. In Visual Basic, you do not need to supply any parameters that are optional, because the Visual Basic runtime provides a generic parameter on your behalf with a value that tells the Office 64 msdn magazine A general theme in the extensions is the use of strong typing throughout, and this extends to the type of object returned from heterogeneous collections, without forcing the developer to make a speculative cast on the returned object. Apart from simplifying VSTO Power Tools

Table of Contents Feed for the Digital Edition of MSDN Magazine - December 2008

MSDN Magazine - December 2008 Contents Toolbox CLR Inside Out Advanced Basics Cutting Edge Patterns In Practice Team System Real-World WF Visual Studio OBA Tools SOA Data Access Geneva Framework Test Run Foundations Windows With C++ Going Places End Bracket

MSDN Magazine - December 2008

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