Why C# 4.0 tolerates trailing comma in anonymous objects initialization code? [duplicate]

Answer 1

One reason the trailing commas is good is because of Source Compares. If you update the source and use a source compare tool, then the source compare tool will only show 1 line changed (the new field3. If there was no trailing comma, then source compare will show 2 lines changed because you had to add the comma after the number 3.

var obj = new {
  field1 = "Test",
  field2 = 3,
  }

var obj = new {
  field1 = "Test",
  field2 = 3,
  field3 = "New",
  }