Feature #11848: New #to_b method for String, Symbol, Numeric, NilClass, TrueClass and FalseClass.

• Status: Rejected
• Assignee: matz (Yukihiro Matsumoto)
• Target version: -

[prodis (Fernando Hamasaki de Amorim)]

New to_b method converts strings, symbols, numbers and nil values in a boolean value.

to_b method is available on String, Symbol, Numeric, TrueClass, FalseClass and NilClass classes.

String

Returns true if string is one of t, true, on, y, yes or 1 values. Returns false otherwise.
Ignores trailing spaces and letter cases.

't'.to_b        # => true
'true'.to_b     # => true
'on'.to_b       # => true
'y'.to_b        # => true
'yes'.to_b      # => true
'1'.to_b        # => true

''.to_b         # => false
'0'.to_b        # => false
'2'.to_b        # => false
'-1'.to_b       # => false
'f'.to_b        # => false
'false'.to_b    # => false
'off'.to_b      # => false
'n'.to_b        # => false
'no'.to_b       # => false
'wherever'.to_b # => false

Symbol

Same as symbol.to_s.to_b.

:'1'.to_b      # => true
:t.to_b        # => true
:true.to_b     # => true
:on.to_b       # => true
:y.to_b        # => true
:yes.to_b      # => true

:f.to_b        # => false
:false.to_b    # => false
:off.to_b      # => false
:n.to_b        # => false
:no.to_b       # => false
:wherever.to_b # => false

Numeric

Returns false if number is zero. Returns true otherwise.

Integer

0.to_b  # => false
1.to_b  # => true
2.to_b  # => true
-1.to_b # => true
-2.to_b # => true

Float

0.0.to_b  # => false
0.1.to_b  # => true
1.0.to_b  # => true
-0.1.to_b # => true
-1.0.to_b # => true

BigDecimal

require 'bigdecimal'

BigDecimal('0.0').to_b  # => false
BigDecimal('0.1').to_b  # => true
BigDecimal('1.0').to_b  # => true
BigDecimal('-0.1').to_b # => true
BigDecimal('-1.0').to_b # => true

NilClass

Returns false.

nil.to_b # => false

TrueClass

Returns true.

true.to_b # => true

FalseClass

Returns false.

false.to_b # => false

[prodis (Fernando Hamasaki de Amorim)]

• Tracker changed from Bug to Feature

[marcandre (Marc-Andre Lafortune)]

• Status changed from Open to Feedback
• Assignee set to matz (Yukihiro Matsumoto)

So many decisions in this seem completely arbitrary (and inconsistent), plus you don't give a use case, there's no way this would ever be accepted.

I'd suggest you build your own hash of true/false values and use that.

[matz (Yukihiro Matsumoto)]

• Status changed from Feedback to Rejected

You forgot empty string/array/hash to be false. ;-)
But Ruby is not Python.

Matz.

[Eregon (Benoit Daloze)]

I like the idea of having explicit conversion between booleans/integers, such that 0.to_b => false and true.to_i => 1.
!int.zero? can be a workaround for the first conversion but I only see a ternary condition for the second case.
Also, nil.to_i is already 0.

[prodis (Fernando Hamasaki de Amorim)]

The idea of to_b method is inspired in Rails and Swift:

• ActiveRecord::Type:Boolean in Rails:
  https://github.com/rails/rails/blob/fc4084fc5bdf60c46824094f4d6a362304c047f6/activerecord/lib/active_record/type/boolean.rb#L10
  https://github.com/rails/rails/blob/fc4084fc5bdf60c46824094f4d6a362304c047f6/activerecord/lib/active_record/connection_adapters/column.rb#L8

• NString#boolValue property in Swift:
  https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/index.html#//apple_ref/occ/instp/NSString/boolValue

[naruse (Yui NARUSE)]

• Has duplicate Feature #12012: Add Boolean method added

[avit (Andrew Vit)]

I've had to do this in a few places over the years myself:

TRUTHY_VALUES = [true, 1, '1', 't', 'T', 'true', 'TRUE', 'y', 'Y', 'yes', 'YES']
FALSY_VALUES = [false, 0, '0', 'f', 'F', 'false', 'FALSE', 'n', 'N', 'no', 'NO']

You forgot empty string/array/hash to be false. ;-)

I think the main reason for this is handling user input (from a file like CSV or other), so other types like Array/Hash are not expected there: just basic scalar values.

Still, it probably only makes sense for some specific situations.

[prodis (Fernando Hamasaki de Amorim)]

Andrew Vit wrote:

I've had to do this in a few places over the years myself:

TRUTHY_VALUES = [true, 1, '1', 't', 'T', 'true', 'TRUE', 'y', 'Y', 'yes', 'YES']
FALSY_VALUES = [false, 0, '0', 'f', 'F', 'false', 'FALSE', 'n', 'N', 'no', 'NO']

You forgot empty string/array/hash to be false. ;-)

I think the main reason for this is handling user input (from a file like CSV or other), so other types like Array/Hash are not expected there: just basic scalar values.

Still, it probably only makes sense for some specific situations.

Andrew Vit, you can use wannabe_bool gem: https://github.com/prodis/wannabe_bool