Complex case statments

wontruefree · January 25, 2021, 4:50pm

I am having trouble with some case statements and have tried to reduce the statements down for a bug but then they seem to work. Am I missing something simple?

Here is the case statement that is not compiling.

github.com

wontruefree/braintree/blob/master/src/cli.cr#L68


when Command::None
  exit
when Command::Error
  exit 1
when Command::DisputeCreate
  if opts[:exp_date]?
    expiration_month, expiration_year = opts[:exp_date].split("/")
    expiration_date = Time.utc(year: expiration_year.to_i, month: expiration_month.to_i, day: 1)
  end
  dispute_klass = case opts[:status]? || "open"
  when "open" then Braintree::Operations::Dispute::Sandbox::OpenDispute
  when "won" then Braintree::Operations::Dispute::Sandbox::WonDispute
  when "lost" then Braintree::Operations::Dispute::Sandbox::LostDispute
  else
    raise "the status #{opts[:status]} is not a valid status"
  end
  dispute_klass.new(
    amount: opts.fetch(:amount, BT::Transaction::Sandbox::Amount.authorized),
    card_number: opts.fetch(:card_number, BT::Transaction::Sandbox::Dispute.card_number),
    card_expiration: opts.fetch(:card_expiration, BT::Transaction::Sandbox::Card.valid_expiration)

This fails with the error.

Error: no argument named 'amount'

Matches are:
 - Reference.new()

All three operations have an initializer with and amount argument.

Here is an overly reduced example one with arguments and one without. Both seem to work.
https://play.crystal-lang.org/#/r/ab31
https://play.crystal-lang.org/#/r/ab33

Blacksmoke16 · January 25, 2021, 5:04pm

https://play.crystal-lang.org/#/r/ab37

Issue seems to be when there is another subclass that isn’t accounted for in the case.

wontruefree · January 25, 2021, 5:07pm

Oh wow thanks for figuring that out. Is this something already known by the core team?

straight-shoota · January 25, 2021, 9:13pm

For reference: Discussion continued on the issue tracker in Case with subclasses not working · Issue #10292 · crystal-lang/crystal · GitHub

TLDR; The behaviour is expected, but the error message is terrible.