isAssignableFrom abstract method

Type Assignability Table:

DART TYPE ASSIGNABILITY TABLE
────────────────────────────────────────────────────────────────────────────
From (B) → To (A)                     A.isAssignableFrom(B)   Valid?   Notes
────────────────────────────────────────────────────────────────────────────
Object    ← String                   ✅ true                  ✅      String extends Object
String    ← Object                   ❌ false                 ❌      Super not assignable from subclass
num       ← int                      ✅ true                  ✅      int is a subclass of num
int       ← num                      ❌ false                 ❌      num is broader than int
List<int> ← List<int>                ✅ true                  ✅      Same type
List<T>   ← List<S>                  ❌ false                 ❌      Dart generics are invariant
List<dynamic> ← List<int>            ❌ false                 ❌      Still invariant
A         ← B (B extends A)          ✅ true                  ✅      Subclass to superclass is OK
A         ← C (unrelated)            ❌ false                 ❌      No inheritance/interface link
Interface ← Class implements Itf     ✅ true                  ✅      Implements is assignable to interface
Mixin     ← Class with Mixin         ✅ true                  ✅      Mixed-in type present
dynamic   ← anything                 ✅ true                  ✅      dynamic accepts all types
anything  ← dynamic                  ✅ true (unsafe)         ✅      Allowed but unchecked
Never     ← anything                 ❌ false                 ❌      Never can’t accept anything
anything  ← Never                    ✅ true                  ✅      Never fits anywhere (bottom type)
────────────────────────────────────────────────────────────────────────────

RULE OF THUMB:
A.isAssignableFrom(B) → Can you do: A a = B();
✓ Subclass → Superclass: OK
✗ Superclass → Subclass: Not OK
✓ Class implements Interface → Interface: OK
✗ Interface → Class: Not OK
✓ Identical types: OK
✗ Unrelated types: Not OK

Checks if this type is assignable from the given other type.

Returns true if a value of type other can be assigned to a variable of this type. This follows Dart's assignability rules including inheritance, interfaces, and mixins.