Block scoping change between 1.8 & 1.9

Ruby
1

Hello,

This probably is a rather basic question but I am curious about the
change from static to dynamic scopes between 1.8 and 1.9 for block
scopes. What was the primary motivation for this(my understanding is
most people have moved to static scopes due to odd interaction issues
in most languages)?

Thanks in advance,

Carter.

2

On Sep 13, 2011, at 6:20 PM, Carter C. wrote:

This probably is a rather basic question but I am curious about the
change from static to dynamic scopes between 1.8 and 1.9 for block
scopes. What was the primary motivation for this(my understanding is
most people have moved to static scopes due to odd interaction issues
in most languages)?

I’m not sure how to interpret your question. There are differences in
the scope of block variables between 1.8 and 1.9 but I don’t think I’ve
ever seen ‘static’ and ‘dynamic’ used to describe the differences.
There are also differences in the constant lookup rules and they are
different between 1.8, 1.9.1, and 1.9.2 and in that case ‘static’ and
‘dynamic’ might indeed be helpful in understanding the issues.

IMHO it isn’t worth trying to understand 1.9.1 rules. Just focus on
1.9.2 if you’ve got questions.

Anyway, back to block variables in 1.9.2. The basic reason for the
change there was to have block parameters shadow any variables in the
outer scope. In general this keeps a programmer from inadvertently
trashing the value of a local variable or formal parameter with a block
variable. It does break some code that depended on the 1.8.7 behavior
(where block variables reused the outer scope).

As for the rules on constants, I’m not 100% up to speed on the changes
so I suggest some googling for answers in that area or perhaps a more
focused question posted here.

Gary W.

3

Thanks Gary.