ConstructorGuardAttribute
NexusLabs.Needlr.Generators¶
ConstructorGuardAttribute Class¶
Requests a constructor guard clause for a field participating in generated constructor generation or a property participating in a generated positional-record constructor overload.
Inheritance System.Object 🡒 System.Attribute 🡒 ConstructorGuardAttribute
Example¶
public partial class TenantService
{
[ConstructorGuard(ConstructorGuardKind.NotNullOrWhiteSpace)]
private readonly string _tenantName;
}
public partial class OrderService
{
[ConstructorGuard(typeof(CollectionNotEmptyGuard))]
private readonly IReadOnlyCollection<Order> _orders;
}
// Generated call: CollectionNotEmptyGuard.Validate(orders, nameof(orders));
public partial class RetryPolicy
{
[ConstructorGuard(typeof(NumberGuards), nameof(NumberGuards.ValidatePositive))]
private readonly int _retryCount;
}
// Generated call: NumberGuards.ValidatePositive(retryCount, nameof(retryCount));
public partial class OrderService
{
[ConstructorGuard(ConstructorGuardKind.NotNullOrWhiteSpace)]
[ConstructorGuard(typeof(OrderIdFormatGuard))]
private readonly string _orderId;
}
// Generated calls, in declaration order:
// global::System.ArgumentException.ThrowIfNullOrWhiteSpace(orderId);
// OrderIdFormatGuard.Validate(orderId, nameof(orderId));
public partial record PreparedRequest(string Query)
{
[RecordConstructorOverloadParameter]
[ConstructorGuard(ConstructorGuardKind.NotNull)]
public PreparedScope? PreparedScope { get; init; }
}
Remarks¶
On an eligible field, applying this attribute with any kind other than None, or with a custom guard type, is itself a positive trigger: it enables constructor generation with None even if the containing class does not carry GenerateConstructorAttribute. On a property, the guard is valid only when the property also carries RecordConstructorOverloadParameterAttribute; a property guard does not trigger an overload by itself.
A custom guard type must expose an accessible static method
compatible with void Validate(T value, string parameterName), where
T is compatible with the guarded member's type. The generator emits a
direct, fully-qualified call to that method -- never a reflection-based invocation.
This attribute may be applied more than once to the same field or participating property to request several guards additively. The class-level default guard (when applicable) is always composed first, followed by every explicit ConstructorGuardAttribute in source declaration order. Identical effective guard calls -- the same built-in ConstructorGuardKind, or the same resolved custom guard type and method -- are emitted only once even if requested more than once.
Constructors¶
ConstructorGuardAttribute(ConstructorGuardKind) Constructor¶
Initializes a new instance of the ConstructorGuardAttribute class requesting a built-in guard kind.
Parameters¶
kind ConstructorGuardKind
The built-in guard clause to emit for this member.
ConstructorGuardAttribute(Type) Constructor¶
Initializes a new instance of the ConstructorGuardAttribute class
requesting a custom guard type using the conventional Validate method.
Parameters¶
guardType System.Type
A type exposing an accessible static method named
Validate, compatible with void Validate(T value, string parameterName).
ConstructorGuardAttribute(Type, string) Constructor¶
Initializes a new instance of the ConstructorGuardAttribute class requesting a custom guard type and an explicit validation method name.
Parameters¶
guardType System.Type
A type exposing an accessible static method matching
methodName, compatible with
void Validate(T value, string parameterName).
methodName System.String
The name of the static validation method to call, typically supplied via nameof.
Properties¶
ConstructorGuardAttribute.GuardType Property¶
Gets the custom guard type supplied to this attribute, or null when a built-in Kind was supplied instead.
Property Value¶
ConstructorGuardAttribute.Kind Property¶
Gets the requested built-in guard kind, or None when a custom GuardType was supplied instead.
Property Value¶
ConstructorGuardAttribute.MethodName Property¶
Gets the explicit validation method name supplied to this attribute, or
null when the conventional Validate method name applies.