Waffling (was Re: single-line terinary operators considered harmful)

[Steven Taschuk]

Quoth Stephen Horne:
  [...]
> When I was saying that optionalness of the semicolon makes the
> difference between separation and termination, [...]

So, in Python:
	[1, 2, 3,]
	[1, 2, 3]
Is the comma a terminator or a separator?

  [...]
> A fairly common would be something like...
> 
>   void strcpy_alike (char *p_Dest, char *p_Src)
>   {
>     while ((*p_Dest++ = *p_Src++) != 0);
>   }
> 
> <loud retching noises>

A bit off-topic, but imho a minor style change improves this
dramatically:
	while ((*p_Dest++ = *p_Src++) != 0)
		;
With the semicolon all lonesome on the next line, it is very
noticeable; it shouts "this statement intentionally left blank". 

Now and then I use 'pass' in Python in a similar way:
    def nop():
        """Do nothing."""
        pass # not required by the syntax
(Also useful in empty class definitions that have docstrings.)

  [...]
> I've seen languages where no operators could shortcircuit, and I've
> seen plenty of languages where functions use lazy evaluation. In
> Python, I'd be surprised if the expression '0 * x' was shortcircuited
> even though it uses an operator and the right-hand-side is redundant.
  [...]

It's not redundant at all: 0*1 and 0*[] yield objects of different
types; if x is an instance of a user-defined vector class, the
multiplication should return the zero vector, not 0; and so forth.
The second operand must be evaluated to achieve this polymorphism.

-- 
Steven Taschuk                                     staschuk at telusplanet.net
Receive them ignorant; dispatch them confused.  (Weschler's Teaching Motto)