Question

What I would like to do, is be able to pass two attributes to a user control, a ListName and a Permission, like so:

<uc:check id="uc" List="Shared Documents" Permission="OpenItems" runat="server">
  <!-- have some HTML content here that is rendered if the permission is true -->
</uc:check>

Then in the actual check user control, have something similar to:

<%@ Control language="C#" ClassName="check" %>
<% 
  // determine permission magic placeholder
  if (DoesUserHavePermissions(perm))
  {
    // render nested HTML content
  }
  else
  {
    // abort rendering as to not show nested HTML content
  }
%>

I have read the page on creating a templated control on MSDN, and while that would work – it really seems to be a bit overkill for what I am trying to do. Is there a control that already renders content based on a boolean expression or a simpler template example?

http://msdn.microsoft.com/en-us/library/36574bf6.aspx

Update:

The following code can be used in the ascx to model a very simple version of this:

<%@ Control Language="C#" ClassName="PermissionCheck" %>
<%@ Import Namespace="System.ComponentModel"  %>
<script runat="server">
    void Page_Init()
    {
        if (Allowed != null)
        {
            Panel container = new Panel();
            Allowed.InstantiateIn(container);
            PermissionBasedMessage.Controls.Add(container);
        }
    }

    [PersistenceMode(PersistenceMode.InnerProperty)]
    public ITemplate Allowed { get; set; }
</script>
<asp:Placeholder runat="server" ID="PermissionBasedMessage" />

Note: I oversimplified the check in the Page_Init method for this sample code. Additional logic checks can be added as needed.

And reference it in the calling HTML page:

<%@ Register src="PermissionCheck.ascx" tagname="PermissionCheck" tagprefix="uc1" %>

<uc1:PermissionCheck ID="PermissionCheck1" runat="server">
  <Allowed>Allowed Access</Allowed>
</uc1:PermissionCheck>

Answer 1

The other answers are good for the generic form of your question, but for checking permissions SPSecurityTrimmedControl might do what you need.