Re: variable declaration

[Nick Coghlan]

Alexander Zatvornitskiy wrote:
var epsilon=0
var S
S=0
while epsilon<10:
  S=S+epsilon
  epselon=epsilon+1#interpreter should show error here,if it's in "strict mode"
print S
It is easy, and clean-looking.
Alexander, [EMAIL PROTECTED]
An alternate proposal, where the decision to request rebinding semantics is made 
at the point of assignment:

epsilon = 0
S = 0
while epsilon < 10:
  S .= S + epsilon
  epselon .= epsilon + 1 #interpreter should show error here
print S
Of course, this is a bad example, since '+= ' can be used already:
S = 0
epsilon = 0
while epsilon<10:
  S += epsilon
  epselon += 1 #interpreter DOES show error here
print S
However, here's an example where there is currently no way to make the rebinding 
intent explicit:

def collapse(iterable):
    it = iter(iterable)
    lastitem = it.next()
    yield lastitem
    for item in it:
        if item != lastitem:
            yield item
            lastitem = item
With a rebinding operator, the intent of the last line can be made explicit:
def collapse(iterable):
    it = iter(iterable)
    lastitem = it.next()
    yield lastitem
    for item in it:
        if item != lastitem:
            yield item
            lastitem .= item
(Note that doing this *will* slow the code down, though, since it has to check 
for the existence of the name before rebinding it)

Cheers,
Nick.
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Nick Coghlan   |   [EMAIL PROTECTED]   |   Brisbane, Australia
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