From: Phillip Gawlowski <cmdjackryan@...>
Date: 2008-05-02T05:37:50+09:00
Subject: Re: Please explain nuances of ||=

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David A. Black wrote:

|> No, it means: x = x || y
|
| This is becoming a bit of a perma-thread :-)
|
| See Robert K.'s answer, and also have a look at the blog post I
| mentioned in my response. It's about exactly why x = x || y is not the
| right expansion for x ||= y.


x ||= y expands into x = x || y, since x == 1 expands to x = x + 1, and
we have no reason to expect ||= to behave differently (MPLOS).

Also, it works as expected if the expansion x = x || y is correct. After
all:

'The or and || operators evaluate their first operand. If true, the
expression returns the value of their first operand; otherwise, the
expression returns the value of the second operand.'
Programming Ruby, 2nd Edition (p. 326).

And Robert's answer works the way it works because the Hash has a
default value set, which doesn't equate to false or nil. If you override
the default value by setting the value to false, the assignment works
again as expected.

- --
Phillip Gawlowski
Twitter: twitter.com/cynicalryan
Blog: http://justarubyist.blogspot.com

Zero raised to the nth power remains zero.
~ -- Pop Baslim
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