Question

I’m converting a bunch of foxweb programs to asp.net. Some of the functions I invoke in the asp code use “external functions,” by which I mean functions that I have defined in .vb files. For example, FileExists() is a nice function I would like to pull out into a common thing called clsCommon.vb .

I have implemented it like this:

Option Explicit On 
Option Strict On

Imports System
Imports System.Web.UI
Imports System.Web.UI.Page

Public Class clsCommon
    Inherits Page

    Public Shared Function FileExists(ByVal filename As String) As Boolean
        If Dir$(filename) <> "" Then
            Return True
        Else
            Return False
        End If
    End Function

End Class

I have tried using both DIR$() and DIR(). In each case, the error returned on the web page reads:

Compiler Error Message: BC30451: Name ‘Dir’ is not declared.

As with other functions I have written I invoke FileExists() something like this:

<%@ page  Debug="true" inherits="clsCommon" src="clsCommon.vb" %>
<%

Dim filename as String = "example.txt"

If clsCommon.FileExists(filename) then
  Response.Write(filename & " Exists")
else
  Response.Write(filename & " does not Exist")
end if

%>

Note 1: While I want to solve this specific problem, what I’m really looking for is the general way to get to these functions like DIR(), CHR(), etc., that I have come to rely on in VB.

Note 2: asp seems to only look at the vb text file – and not at the compiled dll file, so I don’t think the references I use have any effect on it.

Anyone see what I’m missing?

Answer 1

TheGeekYouNeed is certainly right. The best approach is to either keep your code in VB (if it ain’t broke, don’t fix it) or consider investing some time in learning .Net

I have seen code conversion tools for turning VB code into VB.Net. I can’t imagine them working for non-trivial projects though. Likewise, you can go out of your way to keep your code as ‘VB like’ as possible, but I think it’s like burning down your house to avoid having to sweep the floor.

Anyway, the DIR function does still exist in the Microsoft.VisualBasic namespace.
http://msdn.microsoft.com/en-us/library/dk008ty4(v=vs.71).aspx

The more generally accepted way of doing this in .NET would be to use File.Exists
http://msdn.microsoft.com/en-us/library/system.io.file.exists.aspx