From: Gavin Sinclair <gsinclair@...>
Date: 2003-12-29T06:57:39+09:00
Subject: Re: Inconsistent value of uninitialized variable

On Monday, December 29, 2003, 4:29:45 AM, Nathaniel wrote:

> On Dec 28, 2003, at 09:04, Gavin Sinclair wrote:

>> This, to me, is inconsistent and undesirable behaviour.  I would
>> prefer this:
>>
>>   x = x     # NameError: undefined local variable or method `x' ...
>>
>> I haven't given it much thought, but the existing behaviour cost me 15
>> minutes debugging, and I:
>>  * don't see a benefit of the existing behaviour;
>>  * do see a benefit (consistency) of changing the behaviour.

> Isn't it this behavior that makes it possible to define a recursive 
> block?

>    y = 0
>    x = proc{y += 1; x.call unless(y == 100); y}
>    p x.call

I don't believe so, because the 'x' in question above is not being
assigned; 'x.call' is semantically equivalent to 'x' (an rvalue), not
'x = something' (an lvalue).

What makes the above code possible is that 'x' in 'x.call' is not
evaluated until it is actually run; there's no compiler to please.

Gavin