ast.Assign.targets is a list

a, b = c, d

Yields following AST:

Assign(
  targets=[
    Tuple(
      elts=[
        Name(id='a', ctx=Store()),
        Name(id='b', ctx=Store())],
      ctx=Store())],
  value=Tuple(
    elts=[
      Name(id='c', ctx=Load()),
      Name(id='d', ctx=Load())],
    ctx=Load()))

Under what conditions target would be a list with multiple elements instead of single Tuple ?

ast.Assign.targets is a list

a, b = c, d

Yields following AST:

Assign(
  targets=[
    Tuple(
      elts=[
        Name(id='a', ctx=Store()),
        Name(id='b', ctx=Store())],
      ctx=Store())],
  value=Tuple(
    elts=[
      Name(id='c', ctx=Load()),
      Name(id='d', ctx=Load())],
    ctx=Load()))

Under what conditions target would be a list with multiple elements instead of single Tuple ?

• python
• python-ast

• I do not know enough about syntax notation to answer this, but for those who do, I suspect the answer is somewhere in the # ASSIGNMENT TARGETS section of the grammar spec – juanpa.arrivillaga Commented Feb 10 at 19:14

1 Answer 1

When there are multiple destinations for the assignment of the value. That is:

a = b = c = d

AST:

Module(
  body=[
    Assign(
      targets=[
        Name(id='a', ctx=Store()),
        Name(id='b', ctx=Store()),
        Name(id='c', ctx=Store())],
      value=Name(id='d', ctx=Load()))],
  type_ignores=[])