Truth — Gubbins Documentation

Truth vs. Validation

Truth extensions are pure boolean checks — they never throw exceptions. For throwing on invalid input, use the Validation extensions instead.

Collections

`None<T>()`

Extension

Returns true when a collection is null or contains no elements. A concise, readable alternative to the common null-and-count guard pattern.

Signature

public static bool None<T>(this ICollection<T>? collection)

Parameters

Name	Type	Description
collection	ICollection<T>?	The collection to inspect. Null is treated as empty.

Returns

Value	When
true	Collection is `null` or has zero elements.
false	Collection has one or more elements.

Examples

// Before Gubbins
if (items == null || items.Count == 0)
{
    return "No items found.";
}

// With Gubbins
if (items.None())
{
    return "No items found.";
}

// Practical: early-exit guard
public Result ProcessOrders(List<Order>? orders)
{
    if (orders.None())
    {
        return new Result("No orders to process.");
    }

    foreach (Order order in orders!)
    {
        ProcessOrder(order);
    }

    return new Result();
}

// Works with any ICollection<T>
ICollection<string>? tags = null;
bool noTags = tags.None(); // true

List<int> emptyList = new List<int>();
bool isEmpty = emptyList.None(); // true

List<int> populated = new List<int> { 1, 2, 3 };
bool hasItems = populated.None(); // false

`None<T>(predicate)`

Extension

Returns true when a collection is null, empty, or contains no elements that satisfy a predicate. A readable counterpart to !collection.Any(predicate) with added null safety.

Signature

public static bool None<T>(
    this ICollection<T>? collection,
    Func<T, bool> predicate
)

Parameters

Name	Type	Description
collection	ICollection<T>?	The collection to inspect. Null is treated as empty.
predicate	Func<T, bool>	A function that tests each element. Returns `true` if an element matches.

Returns

Value	When
true	Collection is null, empty, or no element satisfies the predicate.
false	At least one element satisfies the predicate.

Examples

// Before Gubbins
if (users == null || !users.Any(u => u.IsAdmin))
{
    return "No admins available.";
}

// With Gubbins
if (users.None(u => u.IsAdmin))
{
    return "No admins available.";
}

// Check for pending items
List<Order> orders = GetOrders();

if (orders.None(o => o.Status == OrderStatus.Pending))
{
    Console.WriteLine("Nothing to process.");
    return;
}

// Check for overdue tasks
bool noOverdue = tasks.None(t => t.DueDate < DateTime.UtcNow);

// Null-safe — no null check needed first
ICollection<string>? tags = null;
bool noLongTags = tags.None(t => t.Length > 10); // true

Numerics

`IsBetween`

Extension

Returns true when an integer falls within an inclusive range. A pure boolean check — use EnsureBetween if you want to throw on out-of-range values.

Invalid range definition

If startOfRange is greater than endOfRange, an ArgumentException is thrown as this represents a programming error.

Signature

public static bool IsBetween(
    this int value,
    int startOfRange,
    int endOfRange
)

Parameters

Name	Type	Description
value	int	The integer to test.
startOfRange	int	Inclusive lower bound. Must be ≤ `endOfRange`.
endOfRange	int	Inclusive upper bound. Must be ≥ `startOfRange`.

Returns & Throws

Outcome	Detail
true	Value is ≥ `startOfRange` and ≤ `endOfRange`.
false	Value is outside the range.
ArgumentException	Thrown when `startOfRange > endOfRange`.

Examples

// Basic range check
int score = 75;
bool passing = score.IsBetween(50, 100); // true
bool failing = score.IsBetween(0, 49);   // false

// Conditional logic
public string GetRating(int score)
{
    if (score.IsBetween(90, 100)) { return "Excellent"; }
    if (score.IsBetween(70, 89))  { return "Good"; }
    if (score.IsBetween(50, 69))  { return "Average"; }
    return "Below average";
}

// Readable guard clause (non-throwing)
public void ApplyDiscount(int loyaltyPoints)
{
    if (!loyaltyPoints.IsBetween(100, 10000))
    {
        logger.LogWarning("Unexpected loyalty points value: {Points}", loyaltyPoints);
        return;
    }

    ApplyPointsDiscount(loyaltyPoints);
}

// Boundary values are inclusive
5.IsBetween(5, 10);  // true
10.IsBetween(5, 10); // true
4.IsBetween(5, 10);  // false
11.IsBetween(5, 10); // false