Negative effects of using a generic function like this?

Question

My question here is, what are the negative effects of using a generic function such as this? Calling this function does work, and in a test console module, it compiles perfectly fine. I do know this is not a strongly typed function, and is %100 bad practice. But it works... perfectly. The purpose of a function like this, would be to handle string input that needs to be inserted in a particular format depending on the type. I also read some other questions on this here on stackoverflow, and suggestions pointed to using (Of T) functions, and variations like that. Why not do it this way? or is there another simple way of accomplishing this without creating a whole nothing class or larger amounts of code. I know this isn't the "elegant" way of handling this either, so if anyone has suggestions, I'm all ears. Thank you! :)

Private Function ConvertFieldValueByType(ByVal type As Field_Type, ByVal value As     String)

    If type = Field_Type.FIELD_TYPE_DATE Then

        Dim dt As Date = DirectCast(TypeDescriptor.GetConverter(New Date(1990, 5,  6)).ConvertFrom(value), Date)

        Return dt

    ElseIf type = Field_Type.FIELD_TYPE_DATETIME Then

        Dim dt As DateTime = DirectCast(TypeDescriptor.GetConverter(New DateTime(1990, 5, 6)).ConvertFrom(value), DateTime)

        Return dt

    ElseIf type = Field_Type.FIELD_TYPE_BLOB Then

        Return value

    ElseIf type = Field_Type.FIELD_TYPE_LIST Then

        Return value

    ElseIf type = Field_Type.FIELD_TYPE_LONG Then

        Return Convert.ToInt64(value)

    ElseIf type = Field_Type.FIELD_TYPE_NUMBER Then

        Return Convert.ToInt32(value)

    ElseIf type = Field_Type.FIELD_TYPE_SHORT Then

        Return Convert.ToInt16(value)

    ElseIf type = Field_Type.FIELD_TYPE_STRING Then

        Return value

    ElseIf type = Field_Type.FIELD_TYPE_TIME Then

        Dim dt As DateTime = DirectCast(TypeDescriptor.GetConverter(New DateTime(1990, 5, 6)).ConvertFrom(value), DateTime)

        Return dt

    ElseIf type = Field_Type.FIELD_TYPE_UNKNOWN Then

        Return value

    Else

        Return value

    End If

End Function

Answer 1

Yes, sometimes things like that become necessary, especially if the final type is not known at compile time (making most other solutions awkward). My main feedback/observation would be: Field_Type looks to be an enum, so you could make this tidier and more efficient with a Switch. Re naming, I would probably call that something related to ...Parse... since it takes a String (perhaps with a matching ...Format... that does the reverse), and I think some of the returns (especially "blob" and "list") look a bit dubious. But otherwise: it gets the job done.

Minor point: your GetConverter code can take a type rather than having to init a struct each time; in C# terms, typeof(DateTime) etc.