[Python-ideas] Visually confusable unicode characters in identifiers

[Oscar Benjamin]

On 1 October 2012 20:33, Mathias Panzenböck
<grosser.meister.morti at gmx.net> wrote:
>
> On 10/01/2012 07:48 PM, Georg Brandl wrote:
>>
>> On 10/01/2012 07:02 PM, Mathias Panzenböck wrote:
>>>
>>> On 10/01/2012 06:43 PM, Robert Kern wrote:
>>>>
>>>> On 10/1/12 5:07 PM, Mathias Panzenböck wrote:
>>>>>
>>>>> I still don't understand why unicode characters are allowed at all in identifier
>>>>> names. Is the reason for this written down somewhere?
>>>>
>>>>
>>>> http://www.python.org/dev/peps/pep-3131/#rationale
>>>>
>>>
>>> But the Python keywords and more importantly the documentation is English. Don't you need to be able
>>> to speak/write English in order to code Python anyway? And if you keep you code+comments English you
>>> can access a much larger developer pool (all developers who speak English should by my hypothesis be
>>> a superset of all developers who speak a certain language).
>>
>>
>> Please; the PEP has been discussed quite a lot when it was proposed,
>> and believe me, yours is not an unfamiliar argument :)  You're about
>> 5 years late.
>>
>> Georg
>>
>
> I didn't want to start a discussion. I just wanted to know why one would implement such a language feature. Guido's answer cleared it up for me, thanks. I can see the purpose in an educational setting (not in production code of anything a little bit bigger).

Non-ascii identifiers have other possible uses. I'll repost the case
that started this discussion on python-tutor (attached in case it
doesn't display):

'''
#!/usr/bin/env python3
# -*- encoding: utf-8 -*-

# Parameters
α = 1
β = 0.1
γ = 1.5
δ = 0.075

# Initial conditions
xₒ = 10
yₒ = 5
Zₒ = xₒ, yₒ

# Solution parameters
tₒ = 0
Δt = 0.001
T = 10

# Lotka-Volterra derivative
def f(Z, t):
    x, y = Z
    ẋ = x * (α - β*y)
    ẏ = -y * (γ - δ*x)
    return ẋ, ẏ

# Accumulate results from Euler stepper
tᵢ = tₒ
Zᵢ = Zₒ
Zₜ, t = [], []
while tᵢ <= tₒ + T:
    Zₜ.append(Zᵢ)
    t.append(tᵢ)
    Zᵢ = [Zᵢⱼ+ Δt*Żᵢⱼ for Zᵢⱼ, Żᵢⱼ in zip(Zᵢ, f(Zᵢ, tᵢ))]
    tᵢ += Δt

# Output since I don't have plotting libraries in Python 3
print('t', 'x', 'y')
for tᵢ, (xᵢ, yᵢ) in zip(t, Zₜ):
    print(tᵢ, xᵢ, yᵢ)
'''

Oscar
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