Types immutable should be tagged with ImmutableAttribute

Rule ND1910 Immutability

How to fix

CQLinq source

This rule is written in CQLinq, C# LINQ over the NDepend code model. It ships with every new NDepend project: you can read it, adapt it, or use it as a starting point for your own custom rules.

// <Name>Types immutable should be tagged with ImmutableAttribute</Name>
// <Id>ND1910:TypesImmutableShouldBeTaggedWithImmutableAttribute</Id>

// warnif count > 0   <-- not a code rule per default

from t in Application.Types where 
  !t.HasAttribute ("NDepend.Attributes.ImmutableAttribute".AllowNoMatch()) && 
   t.IsImmutable && 
   // Don't need to tag record classes with [Immutable]
  !t.IsRecord &&
  !t.IsStructure // An immutable structure must be marked as readonly
select new { 
   t, 
   t.NbLinesOfCode,
   Debt = 3.ToMinutes().ToDebt(),
   Severity = Severity.Low
}

//<Expl>
// The *{0}* is immutable which makes it easy to work with, especially 
// in concurrent scenarios.
// Create an *ImmutableAttribute* attribute and tag this type with it.
// This way the intent to keep it immutable is clearly
// expressed and regularly checked through the rule 
// *Types tagged with ImmutableAttribute must be immutable*.
//</Expl>

//<Desc>
// A type is immutable if its instance fields are only assigned inline or
// from constructor(s). This query lists immutable types not tagged with
// **NDepend.Attributes.ImmutableAttribute**. The attribute expresses in
// source code the intention that a class is and should remain immutable —
// an intention continuously checked by the rule *Types tagged with
// ImmutableAttribute must be immutable*.
//</Desc>

//<HowToFix>
// Tag matched types with **ImmutableAttribute** from *NDepend.API.dll*, or
// your own attribute (adapting this query).
//</HowToFix>

Open in the interactive Rules Explorer · All default rules

Immutability: all 15 items

• Fields should be marked as ReadOnly when possible ND1900
• Avoid non-readonly static fields ND1901
• Avoid static fields with a mutable field type ND1902
• Structures should be immutable ND1903
• Immutable struct should be declared as readonly ND1914
• Property Getters should be pure ND1904
• A field must not be assigned from outside its parent hierarchy types ND1905
• Don't assign a field from many methods ND1906
• Do not declare read only fields with mutable reference types ND1907
• Public read only array fields can be modified ND1908
• Types tagged with ImmutableAttribute must be immutable ND1909
• Types immutable should be tagged with ImmutableAttribute ND1910
• Methods tagged with PureAttribute must be pure ND1911
• Pure methods should be tagged with PureAttribute ND1912
• Record should be immutable ND1913