presence and blank? is same, even, presence more bad than present?(at least, latter return Boolean)

This isn't accurate. A nil returned by presence is special in Crystal in ways that a false returned by present? is not. The presence call offers a compile-time guarantee that present? does not. In Crystal, truthiness and falsiness are semantically equivalent to actual Bool values, but present? can't remove the Nil type.

require "uri/params"

params = URI::Params{"name" => "ajsdfhads"}

if name1 = params["name"]?.presence
  puts typeof(name1) # => String
end

if (name2 = params["name"]?).present?
  puts typeof(name2) # => (String | Nil)
end

class String
  def present?
    !blank?
  end
end

struct Nil
  def present?
    false
  end
end

The value present? returns can be trivially derived from presence with !!. This is a common idiom in both Crystal and Ruby to coerce truth-vs-falsy into true-vs-false. In the above code example, !!name1 will always be the same as name2. If you need a Bool, such as when sending the value over the wire or to a method that only accepts a Bool, coercing the value only takes 2 characters.

present? offers nothing that presence doesn't already provide, but presence offers value that present? does not. This is what I meant above by present? providing little to no semantic value over presence.

Uh oh!

Add String#present? method. #16757

Description

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions