What are const Constructors in Dart?

First, you need to understand the terms final, const, and compile-time constant.

• final
  • Initialized only once after initialization starts
  • Reassignment is not allowed
  • The contents of the allocated memory can be modified

    • final hoge = [1,2,3]
      hoge = [] // Error
      hoge[0] = 10 // No error
      

• const
  • A constant determined at compile time = compile-time constant
  • Reassignment is not allowed
  • The contents of the allocated memory cannot be modified either

     const hoge = [1,2,3]
     hoge = [] // Error
     hoge[0] = 10 // Error
    

• What is a compile-time constant?

  • Including variables specified as const, the more general concept is the "compile-time constant".

    • https://qiita.com/uehaj/items/7c07f019e05a743d1022#コンパイル時定数
  • Literals such as 1, "abc", or [1,2,3]. In short, values that are not determined dynamically.

What is a const constructor?

• Based on the above, a const constructor is:
  • A class constructor that only accepts compile-time constants as arguments

Reference Links

• Dart variable definition modifiers static/final/const, and about const constructor - Qiita