[Python-ideas] Making stars optional? (was: Making colons optional?)

[Lie Ryan]

On Sat, 07 Feb 2009 12:19:50 -0200, Leonardo Santagada wrote:

> On Feb 7, 2009, at 12:21 AM, Steven D'Aprano wrote:
> 
>> George Sakkis wrote:
>>> On Fri, Feb 6, 2009 at 6:59 PM, Steven D'Aprano
>>> <steve at pearwood.info> wrote:
>>>>> In maths,
>>>>> you only have single-character variable names (sub-/superscripts
>>>>> notwithstanding), so ab always means a*b.
>>>> Except in the presence of typos.
>>> In the presence of typos all bets are off, unless you are aware of any
>>> typo-proof writing system. Python certainly isn't one since, say,
>>> "x.y" and "x,y" are pretty similar, both visually and in keyboard
>>> distance.
>>
>> You overstate your case: not *all* bets are off, just some of them.
>>
>> Some typos have greater consequences than others. Some will be
>> discovered earlier than others, and the earlier they are discovered,
>> the more likely they are to be easily fixed without the need for
>> significant debugging effort.
>>
>> E.g. if I type R**$ instead of R**4, such a typo will be picked up in
>> Python immediately. But R**5 instead could be missed for arbitrarily
>> large amounts of time.
>>
>> E.g. if you mean x.y but type x,y instead, then such an error will be
>> discovered *very* soon, unless you happen to also have a name 'y'.
>>
>> But anyway, we're not actually disagreeing. (At least, I don't think we
>> are.) We're just discussing how some conventions encourage errors and
>> others discourage them, and the circumstances of each.
> 
> 
> This doesn't really makes much sense to me... if you don't use tests to
> verify your program both R**5 or R**A are just the same error if for
> example this code path is a rare case, it will only be discovered when
> something goes wrong with the program...

If that piece of code is in a rarely walked path, then it is even worse 
since the bug could easily creep into production release without anyone 
noticing. 

It happens that there are three classifications of errors in programming:
Syntax Error - easily found, impossible to creep into production release 
since compiler/interpreter would complaint loudly
Runtime Error - found when the code path is walked, comprehensive testing 
would reveal such errors
Logic Error - hard to find, hard to debug

It happens that most typos would become SyntaxError and LogicError. 
Implicit multiplication currently becomes a SyntaxError, since python 
recognizes no implicit multiplication, OTOH if we introduce implicit 
multiplication, it'll invariably becomes Logic Error or Runtime Error.