Bug #10996: Inline if statements should hoist variables.

• Status: Rejected
• Assignee: -
• Target version: -
• ruby -v: ruby 2.1.1p76 (2014-02-24 revision 45161) [x86_64-darwin13.0]
• Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN

[josh.cheek (Josh Cheek)]

A multiline if statement hoists local variables to the parent scope. An inline if statement does not.

We can see that in this first example, the a declared in the conditional is available both in the body and in the parent, after the if-statement is executed.

if a = 'A'
  a # => "A"
end
a # => "A"

However, when refactoring to an inline-if-statement, the variable is no longer available.

a if a = 'A'  # ~> NameError: undefined local variable or method `a' for main:Object

# ~> NameError
# ~> undefined local variable or method `a' for main:Object
# ~>
# ~> /var/folders/7g/mbft22555w3_2nqs_h1kbglw0000gn/T/seeing_is_believing_temp_dir20150323-47886-ay5rau/program.rb:1:in `<main>'

Inline if statements should hoist variables, too. For both consistency and convenience.

[matz (Yukihiro Matsumoto)]

• Status changed from Open to Rejected

The fundamental rule is that local variables are defined by the first assignment. For consistency, I will not bend this rule for if modifiers.

Matz.

[josh.cheek (Josh Cheek)]

Yukihiro Matsumoto wrote:

The fundamental rule is that local variables are defined by the first assignment. For consistency, I will not bend this rule for if modifiers.

Matz.

That's why it seems like this should be turned on, since it is assigned first. eg the if-statement body would work if it were dynamically accessed.

eval 'a'                       if a = 'A'  # => "A"
binding.local_variable_get 'b' if b = 'B'  # => "B"