CODEWITHSUNDEEP
vbscriptasp-classic
Vixed
Vixed

Reputation: 3509

Check if a sub or a function exist

Is there any way to check if a sub or a function exist?

sub mySub()
 'some code
end sub

something like if exist(mySub)

Upvotes: 9

Views: 5869

Answers (1)

user692942
user692942

Reputation: 16682

Update:

So I knew there was a better method for doing this and it's using GetRef()

Function Exist(procName)
    On Error Resume Next
    Dim proc: Set proc = GetRef(procName)
    Exist = (Not proc Is Nothing)
End Function

Function Hello()
    WScript.Echo "Hello Ran"
End Function

If Exist("test") Then  'Returns False (0)
    WScript.Echo "Test Exists"
Else
    WScript.Echo "Test Doesn't Exist"
End If

If Exist("Hello") Then  'Returns True (-1)
    WScript.Echo "Hello Exists"
Else
    WScript.Echo "Hello Doesn't Exist"
End If

Output

Test Doesn't Exist
Hello Exists

There is nothing built into VBScript to do this but you can build something using On Error Resume Next and ExecuteGlobal().

Function Exist(procName)
    On Error Resume Next
    ExecuteGlobal "Call " & procName & "()"
    Exists = (Err.Number = 0)
End Function

Function Hello()
    WScript.Echo "Hello Ran"
End Function

If Exist("test") Then  'Returns False (0)
    WScript.Echo "Test Exists"
Else
    WScript.Echo "Test Doesn't Exist"
End If

If Exist("hello") Then  'Returns True (-1)
    WScript.Echo "Test Exists"
Else
    WScript.Echo "Test Doesn't Exist"
End If

Output

Test Doesn't Exist
Hello Ran
Test Doesn't Exist

Drawback with this approach is it actually runs the procedure if it exists.

Upvotes: 17

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