interface View
{
    void Update();
}
class DetailsView: View
{
    ReportDocument doc;
    public void Update()
    {
        ...
    }
    public UpdateReportDetails()
    {
        report = doc.GetReportData();
        ...
    }
    ...
}
class SummaryView: View
{
    ReportDocument doc;
    public void Update()
    {
        ...
    }
    public UpdateReportSummary()
    {
        report = doc.GetReportData();
        ...
    }
    ...
}
class ReportDocument
{
    ReportInfo reportInfo;
    DetailsView detailsView;
    SummaryView summaryView;
    public void SetParameters(int a, int b)
    {
        recalculateReportBasedOnParams(a, b);
        summaryView.UpdateReportSummary();
        summaryView.UpdateReportDetails();
    }
    public ReportInfo GetReportData()
    {
        return reportInfo;
    }
    ...
}

interface View
{
    void HandleChange();
}
class DetailsView: View
{
    ReportDocument doc;
    public void HandleChange() { ... }
}
class SummaryView: View
{
    ReportDocument doc;
    public void HandleChange()
    {
        report = doc.GetReportData();
        displayReportSummary(report);
    }
    ...
}
class ReportDocument
{
    ReportInfo reportInfo;
    List<View> views = new List<View>();
    public void SetParameters(int a, int b)
    {
        recalculateReportBasedOnParams(a, b);
        foreach (View v in views)
            v.HandleChange();
    }
    public ReportInfo GetReportData()
    {
        return reportInfo;
    }
    ...
}

interface View
{
    void HandleChange(ReportInfo reportInfo);
}
class DetailsView: View
{
    ReportDocument doc;
    public void HandleChange(ReportInfo reportInfo) { ... }
    ...
}
class SummaryView: View
{
    ReportDocument doc;
    public void HandleChange(ReportInfo reportInfo)
    {
        displayReportSummary(report);
    }
    ...
}
class ReportDocument
{
    ReportInfo reportInfo;
    List<View> views = new List<View>();
    public void SetParameters(int a, int b)
    {
        recalculateReportBasedOnParams(a, b);
        foreach (View v in views)
            v.HandleChange(reportInfo);
    }
    ...
}

interface View
{
    void Update();
}
class DetailsView: View
{
    public void Update() { ... }
    public UpdateReportDetails(ReportInfo report) { ... }
    ...
}
class SummaryView: View
{
    public void Update() { ... }
    public UpdateReportSummary(ReportInfo report) { ... }
    ...
}
class ReportDocument
{
    ReportInfo reportInfo;
    View detailsView;
    View summaryView;
    public void SetParameters(int a, int b)
    {
        recalculateReportBasedOnParams(a, b);
        summaryView.DisplayReportSummary(reportInfo);
        detailsView.DetailsView(reportInfo);
    }
    ...
}