Extending Python Syntax with @

[David MacQuigg]

On Thu, 11 Mar 2004 12:01:57 -0500, Peter Hansen <peter at engcorp.com>
wrote:

>David MacQuigg wrote:
>
>> 'yield' is a little closer to the intent, but again, to most new users
>> it probably means something more like 'give way' or 'acquiesce', the
>> opposite of 'resist'.  If you had never seen 'yield' used as it is now
>> in Python, and your first encounter with generator functions was when
>> you saw @return, would you not think "Ah yes, a modified return.", and
>> would that not be closer to reality than whatever you might associate
>> with the word 'yield'?
>
>No!  The "give way" meaning is _much_ closer to what is going on than 
>"modified return", in my way of looking at it.  Return winds up the call 
>stack and just happens to include a result value.  Yield temporarily 
>"gives way" but leaves the stack frame in place, available for 
>resumption at a later time.  You could say that the result value is 
>incidental, in the return case, while the permanent transfer of context 
>is the key thing.  Just the opposite in the case of yield, and therefore 
>much different from a "modified return".

A normal return terminates the function and returns a result.  A
modified return (yield) suspends the function and returns a result.

>This is all semantics, probably, but I don't believe you can make a 
>strong case that yield is an ill-chosen name.

It's not ill chosen, just arbitrary.  I would be just as happy with
'rtn' or 'tsr' or any fanciful word that doesn't convey a _wrong_
meaning.

We seem to have lost the top of this sub-thread, which is what I was
responding to:

>- Python is a readable language. lambda says "function literal",
>  yield says "generator",

All I'm saying is that these names don't convey the stated meanings to
most new users.  I could be wrong, as I haven't done a survey.

-- Dave