Feature #15076: Struct to raise error when keyword arguments used but not enabled

• Status: Rejected
• Assignee: -
• Target version: -

[macdevign (Macdevign mac)]

When Struct is used to instantiate object with keyword arguments disabled and yet if instantiated using keyword arguments, the instance fields will be set incorrectly.

Will it be clearer if a error is raised instead rather than assigning data incorrectly ? This is helpful and save time in nailing such issue in a large code base when there is mixture of Struct define with and without keyword arguments.

For example,

Info = Struct.new(:name, :country)  # without keyword argument enabled
c = Info.new(name: "myname", country: "Japan") # Instantiate with keywords

The c.name contains hash, and c.country is nil

[nobu (Nobuyoshi Nakada)]

• Related to Feature #11925: Struct construction with kwargs added

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Rejected

Info = Struct.new(:name, :country, keyword_init: true)
c = Info.new(name: "myname", country: "Japan")
p c #=> #<struct Info name="myname", country="Japan">

[k0kubun (Takashi Kokubun)]

Will it be clearer if a error is raised instead rather than assigning data incorrectly ?

With the current keyword arguments implementation (see also: [Feature #14183]), we can't distinguish the mistaken situation with one that we really wanted to initialize only the first argument with Symbol-key Hash. So that would be breaking change which we basically shouldn't introduce.