Lies in education [was Re: The "loop and a half"]

[bartc]

On 13/10/2017 15:39, Steve D'Aprano wrote:
> On Fri, 13 Oct 2017 11:54 pm, Gregory Ewing wrote:
> 
>> Neil Cerutti wrote:
>>> I can tell at a glance if a parameter is expected to be
>>> modifiable just by looking at the function signature.
>>
>> The question is why doesn't anyone feel the need to be
>> able to do that for Python functions? Whether a function
>> modifies things passed to it is just as important to
>> know in Python as it is in C.
> 
> Lots of people would like Python to have a "freeze" function that can make
> immutable objects, it is a moderately common feature request.
> 
> Some people (myself included) would like a "const" declaration that gives us
> names that can only be bound to once:
> 
> const spam = "NOBODY expects the Spanish Inquisition!!!"  # Okay
> spam = "foo"  # Error.

Presumably also:

const def f:
const class c:
const import i


> I don't mind if that is a runtime error, although a compile time error would
> be nicer.

This would be of most use when the byte-code compiler (assuming there is 
one) knows about them. But many will be inside imported modules whose 
contents, AIUI, are not visible to the byte-code compiler.

And then they would be accessed as:

   i.spam

So this would be a const attribute.

-- 
bartc