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class Athena::Console::Question(T)
inherits Reference #

This namespaces contains various questions that can be asked via the ACON::Helper::Question helper or ART::Style::Athena style.

This class can also be used to ask the user for more information in the most basic form, a simple question and answer.


question = ACON::Question(String?).new "What is your name?", nil
name = helper.ask input, output, question

This will prompt to user to enter their name. If they do not enter valid input, the default value of nil will be used. The default can be customized, ideally with sane defaults to make the UX better.

Trimming the Answer#

By default the answer is trimmed in order to remove leading and trailing white space. The ACON::Question::Base#trimmable= method can be used to disable this if you need the input as is.

question = ACON::Question(String?).new "What is your name?", nil
question.trimmable = false
name_with_whitespace_and_newline = helper.ask input, output, question

Multiline Input#

The question helper will stop reading input when it receives a newline character. I.e. the user presses the ENTER key. However in some cases you may want to allow for an answer that spans multiple lines. The ACON::Question::Base#multi_line= method can be used to enable multi line mode.

question = ACON::Question(String?).new "Tell me a story.", nil
question.multi_line = true

Multiline questions stop reading user input after receiving an end-of-transmission control character. (Ctrl+D on Unix systems).

Hiding User Input#

If your question is asking for sensitive information, such as a password, you can set a question to hidden. This will make it so the input string is not displayed on the terminal, which is equivalent to how password are handled on Unix systems.

question = ACON::Question(String?).new "What is your password?.", nil
question.hidden = true


If no method to hide the response is available on the underlying system/input, it will fallback and allow the response to be seen. If having the hidden response hidden is vital, you MUST set ACON::Question::Base#hidden_fallback= to false; which will raise an exception instead of allowing the input to be visible.

Normalizing the Answer#

The answer can be "normalized" before being validated to fix any small errors or tweak it as needed. For example, you could normalize the casing of the input:

question = ACON::Question(String?).new "Enter your name.", nil
question.normalizer do |input|
  input.try &.downcase

It is possible for input to be nil in this case, so that need to also be handled in the block. The block should return a value of the same type of the generic, in this case String?.


The normalizer is called first and its return value is used as the input of the validator. If the answer is invalid do not raise an exception in the normalizer and let the validator handle it.

Validating the Answer#

If the answer to a question needs to match some specific requirements, you can register a question validator to check the validity of the answer. This callback should raise an exception if the input is not valid, such as ArgumentError. Otherwise, it must return the input value.

question = ACON::Question(String?).new "Enter your name.", nil
question.validator do |input|
  next input if input.nil? || !input.starts_with? /^\d+/

  raise "Invalid name. Cannot start with numeric digits."

In this example, we are asserting that the user's name does not start with numeric digits. If the user entered 123Jim, they would be told it is an invalid answer and prompted to answer the question again. By default the user would have an unlimited amount of retries to get it right, but this can be customized via ACON::Question::Base#max_attempts=.



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Direct known subclasses



.new(question : String, default : T) #

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#validator #

Sets the validator callback to this block. See Validating the Answer.

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#validator=(validator : Proc(T, T)?) #

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