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POHow can a base class with abstract methods be used to handle delegate calls?
 

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  1. POHow can a base class with abstract methods be used to handle delegate calls?
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    <p>Here is the base class:</p> <pre><code>using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using Microsoft.Reporting.WinForms; abstract class ReportWinForm : System.Windows.Forms.Form { // This will be the one line of code needed in each WinForm--providing the base class a reference // to the report, so it has access to the SubreportProcessing event protected ReportViewer WinFormReportViewer { get; set; } // Making this abstract requires each derived WinForm to implement GetReportData--foolproof! protected abstract DataResult GetReportData(SubreportProcessingEventArgs e); // Wire up the subreport_processing handler when any WinForm loads // You could override this in derived WinForms classes if you need different behavior for some WinForms, // but I would bet this default behavior will serve well in most or all cases protected virtual void Form1_Load(object sender, EventArgs e) { WinFormReportViewer.LocalReport.SubreportProcessing += new SubreportProcessingEventHandler(LocalReport_SubreportProcessing); } // When the Subreport processing event fires, handle it here // You could also override this method in a derived class if need be protected virtual void LocalReport_SubreportProcessing(object sender, SubreportProcessingEventArgs e) { // Get the data needed for the subreport DataResult dataResult = this.GetReportData(e); e.DataSources.Clear(); e.DataSources.Add(new ReportDataSource(dataResult.Label, dataResult.Table)); } } </code></pre> <p>Here is the concrete implementation:</p> <pre><code>public frmTestAllView() { //base.WinFormReportViewer = reportViewer1; //Hook-up callbacks to the base class ReportWinForm InitializeComponent(); } private void frmTestAllView_Load(object sender, EventArgs e) { // TODO: This line of code loads data into the 'AFC_ObsolescenceDataSet.up_Fill_frmInternalCaseStatus_All' table. You can move, or remove it, as needed. this.up_Fill_frmInternalCaseStatus_AllTableAdapter.Fill(this.AFC_ObsolescenceDataSet.up_Fill_frmInternalCaseStatus_All); this.reportViewer1.RefreshReport(); } // The search parameters will be different for every winform, and will presumably // come from some winform UI elements on that form, e.g., parentPartTextBox.Text protected override DataResult GetReportData(SubreportProcessingEventArgs e) { // Return the data result, which contains a data table and a label which will be // passed to the report data source // You could use DataSet in DataResult instead of DataTable if needed switch (e.ReportPath) { case "rptSubAlternateParts": return new DataResult( new BLL.AlternatePartBLL().GetAlternativePart(parentPartTextBox.Text) , "BLL_AlternatePartBLL" ); case "rptSubGetAssemblies": return new DataResult( new BLL.SubAssemblyBLL().GetSubAssemblies(someOtherTextBox.Text) , "BLL_SubAssemblyBLL" ); default: throw new NotImplementedException(string.Format("Subreport {0} is not implemented", e.ReportPath)); } } </code></pre> <p>There are two problems:</p> <ol> <li><code>DataResult</code> is unrecognized by Visual Studio 2008, even though it is in the ReportWinForm base class.</li> <li>The designer in VS 2008 claims that a class derived from ReportWinForm cannot be edited, even though the base class is descends from <code>Form</code>.</li> </ol> <p>For more context, please see <a href="https://stackoverflow.com/questions/14777799/how-can-a-delegate-respond-to-multiple-events-with-a-generic-and-extensible-clas">How can a delegate respond to multiple events with a generic and extensible class?</a></p>
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      1. POHow can a base class with abstract methods be used to handle delegate calls?
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    1. COI don't see where you define a `DataResult` class "in the ReportWinForm base class". You'll have to provide more detail about what the designer is telling you, there's all sorts of reasons why it can't edit a `Form`-based class.
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      1. POHow can a base class with abstract methods be used to handle delegate calls?
      1. USPeter Ritchie
    2. COAlso, there's many usages of "DataResult", please detail which uses VS is having a problem with and the exact error message(s).
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      1. POHow can a base class with abstract methods be used to handle delegate calls?
      1. USPeter Ritchie
    3. COAlso, in what way are you having a problem with "Delegate" as described in your title?
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      1. POHow can a base class with abstract methods be used to handle delegate calls?
      1. USPeter Ritchie
 

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