Friday Finking: Contorted loops
Terry Reedy
tjreedy at udel.edu
Fri Sep 10 21:30:32 EDT 2021
On 9/10/2021 7:38 AM, Alan Gauld via Python-list wrote:
> But python complicates this tenet still further by adding an else
> clause to its loops. And complicating this still more is that these
> else clauses have almost exactly opposite effects.
To the contrary...
if...else
executes the else part if the condition is false.
>
> while...else...
>
> executes the else if the body of the loop does NOT get executed.
IE, executes the else part if the condition is false.
A while statement is, or can be viewed as, an if statement with a goto
ending the if part.
> for...else...
>
> executes the else iff ALL iterations of the for loop DO complete.
IE, executes the else part of the condition is false.
A for loop is, or can be viewed as syntactic sugar for a while loop.
The condition is that next(iterable) yields a value.
It is possible that the doc could be improved. I have not looked for a
while. Or maybe it needs to be read more.
--
Terry Jan Reedy
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