[ruby-talk:14667] Re: Arggg Bitten by the block var scope feature!!!

Marko Schulz wrote:

# On Fri, May 04, 2001 at 08:51:32AM +0900, David Alan Black wrote:
# > On Fri, 4 May 2001, Conrad Schneiker wrote:
# > 
# > > # On Thu, 3 May 2001, Wayne Scott wrote:
# > > #
# > > # >     #simplified for this discussion
# > > # >     def fetch(arg2)
# > 
# > [snip]
# > 
# > > # >                  @cache.dup.each do |arg2, file|       ## (1)
# > 
# > [snip]
# > 
# > > # I don't know if the behavior should change but I think it should 
at
# > > # least issue a warning if there is reuse like this.
# > >
# > > I think this is an important suggestion.
# > >
# > > Answers such as:
# > >
# > >   1) I should have known better.
# > >   2) You should have known better.
# > >   3) Here is a way around this.
# > >   4) There is (or soon will be) a better feature to use.
# > >   5) Once you know Ruby better, this won't be a problem for you.
# > >
# > > are all true to some degree, but are somewhat beside the point of 
accident
# > > prevention in the cases that people are caught unawares.
# > 
# > I certainly agree that this should not be warned about under -w. 
# 
# I certainly do not agree with you. This should be warned about under -w.
# 
# > In fact...  I'm not sure what the warning would be. 
# 
# Something like 'Warning. Use of local variables as block parameters
# may lead to unexpected side effects.'?
# 
# > I can't help thinking that to a large extent this case would be
# > mostly covered by #5, above.
# 
# I do not agree with you here either. Of course this errors get if you
# have accumulated experience and write new code. But when you start to
# refactor without a tool to aid you, this bites you fast.

Well, I kind of agree with all of you. But I kind of also agree with
myself too. :-) That's why I initially made the following suggestion
that everyone seems to have overlooked:

# Maybe a "last resort" "extra cautious" warning level is needed to deal 
# with things such as this, so that people can habitually run with -w 
# without being overwhelmed with false alarms about issues they know about 

# or have otherwise dealt with.

Just so there is no misunderstanding, this would be *another* (for 
example, -ww or -w2 or -w9) option that gave you the current and 
*unmodified* -w warnings, *plus* things that are known to be *sometimes* 
troublesome for the new non-expert Ruby fans, people who missed their 
morning coffee break, the sleep-deprived, the rushed maintainers of other 
people's code, and so on.

Conrad Schneiker
(This note is unofficial and subject to improvement without notice.)