How undefined values are handled with 'if' modifier.

[michael.j.cannon]

Why do these two expressions give different results when foo is undefined?

foo if (foo = 3) # => NameError: undefined local variable or method `foo' for main:Object
if (foo = 3); foo end # => 3

Granted, an operator like ||= does something handy, even though it's inconsistent with foo = foo || 3
but the if-expression-vs-modifier inconsistency just seems wrong.

- Mike

 

[Robert Klemme]

Why do these two expressions give different results when foo is undefined?

foo if (foo = 3) # => NameError: undefined local variable or method `foo' for main:Object
if (foo = 3); foo end # => 3

Granted, an operator like ||= does something handy, even though it's inconsistent with foo = foo || 3
but the if-expression-vs-modifier inconsistency just seems wrong.

That has been discussed numerous times on ruby-talk. That last
discussion is just a few weeks back.

Bottom line: syntactic order in the source determines from when on a
local variable is defined.

Cheers

robert