parameter_assignments.md

Pattern: Reassigning parameter

Issue: -

Description

Assigning new values to parameters is generally a bad practice unless an operator such as ??= is used. Otherwise, arbitrarily reassigning parameters is usually a mistake.

Example of incorrect code:

void badFunction(int parameter) { // LINT
 parameter = 4;
}

Example of incorrect code:

void badFunction(int required, {int optional: 42}) { // LINT
 optional ??= 8;
}

Example of incorrect code:

void badFunctionPositional(int required, [int optional = 42]) { // LINT
 optional ??= 8;
}

Example of incorrect code:

class A {
  void badMethod(int parameter) { // LINT
  parameter = 4;
 }
}

Example of correct code:

void ok(String parameter) {
 print(parameter);
}

Example of correct code:

void actuallyGood(int required, {int optional}) { // OK
 optional ??= ...;
}

Example of correct code:

void actuallyGoodPositional(int required, [int optional]) { // OK
 optional ??= ...;
}

Example of correct code:

class A {
 void ok(String parameter) {
  print(parameter);
 }
}

Further Reading

• Linter for Dart - parameter_assignments