Databases
StackOverflow2013
Postsdbo
PO.NET C# Visitor Pattern
Body
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO.NET C# Visitor Pattern
    text
    copied!<p>I have parsed XML file into objects, in which each object has a 1:1 relationship with XML node in the file. This object tree implements Composite and Visitor design patterns as per Jeremy Miller's following blog entry:</p> <p><a href="http://codebetter.com/blogs/jeremy.miller/archive/2007/10/31/be-not-afraid-of-the-visitor-the-big-bad-composite-or-their-little-friend-double-dispatch.aspx" rel="nofollow noreferrer">http://codebetter.com/blogs/jeremy.miller/archive/2007/10/31/be-not-afraid-of-the-visitor-the-big-bad-composite-or-their-little-friend-double-dispatch.aspx</a></p> <p>When I iterate object tree, I do some processing in AcceptVisitor() method before double dispatching it. As a part of processing on certain objects, I call certain methods on leafs/children objects. Now, when I traverse child object (as a part of ongoing iteration), I don't want AcceptVisitor() to double dispatch anything. (Double dispatch calls method to write text to the output file. I want to avoid duplicate text in the file. )I achieved this functionality with a flag but I am not satisfied with the flag design. Is there any modified version of Visitor pattern to handle this particular situation? Any other ideas are also welcome. </p> <pre><code>//Iterate object tree public void Iterate(Root root) { foreach (ILeaf child in root.ChildLeaves) { child.AcceptVisitor(this); } } //This method in child object of type ILeaf gets called when Iterate() executes. public void AcceptVisitor(IVisitor visitor) { //Some child object implement ILeaf1 along with ILeaf //I want to avoid any processing in AcceptVisitor() for objects of type ILeaf1 //once following loop executes. //This means Iterate() should not process anyting in AcceptVisitor() for //children of type ILeaf1. IEnumerable&lt;ILeaf1&gt; children = this.ChildLeaves.OfType&lt;ILeaf1&gt;(); //Collection of action statements from child objects. List&lt;ActionStatement&gt; statements = new List&lt;ActionStatement&gt;(); foreach (ILeaf1 s in children) { ActionStatement statement = s.Generate(); statements.Add(statement); } //Output action statements to TextWriter visitor.WriteStatements(statements); } //ILeaf1 object method public void AcceptVisitor(IVisitor visitor) { ActionStatement statement = new ActionStatement("Some Text"); //Output action statement to TextWriter visitor.WriteStatement(statement); } </code></pre>
 

Querying!

 
Guidance
An individual column

Larger individual text columns get their own page to allow for proper reading.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload