unsettable

Unsettable is a term used in computer programming to describe a variable or property that cannot be assigned a value after its initial creation or within a specific scope. This immutability is often a design choice to ensure data integrity or to prevent accidental modification of critical values.

In some programming languages, certain variables are declared as constants, meaning they are unsettable once a value is assigned. For example, a constant might represent a mathematical pi value or a configuration setting that should never change during program execution. Attempting to reassign a value to an unsettable variable typically results in a compilation error or a runtime exception, depending on the language's implementation.

The concept of unsettable can also apply to specific properties of objects. For instance, an object might have a read-only property that can be set during object instantiation but cannot be altered thereafter. This ensures that certain characteristics of an object remain fixed.

The opposite of unsettable is a settable or mutable variable, which can be modified or reassigned multiple times throughout a program's lifecycle. The careful use of unsettable elements contributes to more robust and predictable software by limiting the potential for unintended side effects caused by variable modification.