Is this valid ?

[Colin J. Williams]

Lie wrote:
> On Mar 20, 4:18 am, Stef Mientki <stef.mien... at gmail.com> wrote:
>> hello,
>>
>> by accident I typed a double value test,
>> and to my surprise it seems to work.
>> Is this valid ?
>>
>> a = 2
>> b = 2
>>
>> a == b == 2
>>
>> thanks,
>> Stef Mientki
> 
> a == b == 2
> is equivalent to
> a == b and b == 2
> except that b is only evaluated once for the whole comparison

Yes - there seems to be unanimity.

Comparisons can be chained arbitrarily, 
e.g., x < y <= z is equivalent to x < y 
and y <= z, except that y is evaluated 
only once (but in both cases z is not 
evaluated at all when x < y is found to 
be false).

Formally, if a, b, c, ..., y, z are 
expressions and opa, opb, ..., opy are 
comparison operators, then a opa b opb c 
...y opy z is equivalent to a opa b and 
b opb c and ... y opy z, except that 
each expression is evaluated at most once.

Colin W.