vb-core

Visual Basic .NET Core Patterns

Modern VB.NET (2019+) best practices with focus on type safety, LINQ, async/await, and .NET integration.

Quick Start

' Always enable strict type checking
Option Strict On
Option Explicit On
Option Infer On

' Modern class definition
Public Class Customer
    Public Property Id As Integer
    Public Property Name As String
    Public Property Email As String

    ' Constructor
    Public Sub New(id As Integer, name As String, email As String)
        Me.Id = id
        Me.Name = name
        Me.Email = email
    End Sub
End Class

' Modern async method
Public Async Function GetCustomerAsync(id As Integer) As Task(Of Customer)
    Dim result = Await database.QueryAsync(Of Customer)(
        "SELECT * FROM Customers WHERE Id = @id",
        New With {.id = id}
    )
    Return result.FirstOrDefault()
End Function

' LINQ query
Dim activeCustomers = From c In customers
                      Where c.IsActive AndAlso c.Balance > 0
                      Order By c.Name
                      Select c

Type Safety (Critical)

Option Strict On

' ALWAYS at top of every file
Option Strict On
Option Explicit On
Option Infer On

' Why:
' - Option Strict: Prevents implicit narrowing conversions
' - Option Explicit: Requires variable declaration
' - Option Infer: Enables type inference (but still type-safe)

Explicit Types vs Inference

' ✅ Good: Explicit when clarity helps
Dim customerName As String = GetCustomerName(id)
Dim count As Integer = GetCount()

' ✅ Good: Inference when type is obvious
Dim customer = New Customer(1, "John", "[email protected]")
Dim items = New List(Of String) From {"a", "b", "c"}

' ❌ Bad: Dim without type and no inference
Dim data = GetData()  ' What type is data?

' ✅ Better: Be explicit
Dim data As DataTable = GetData()

Nullable Types

' Modern nullable syntax (VB 15.5+)
Dim middleName As String? = Nothing
Dim age As Integer? = Nothing

' Null-conditional operator
Dim length As Integer? = middleName?.Length

' Null-coalescing operator
Dim displayName As String = middleName If Nothing

' Check for null
If age IsNot Nothing Then
    Console.WriteLine($"Age: {age.Value}")
End If

' GetValueOrDefault
Dim years As Integer = age.GetValueOrDefault(0)