[Python-ideas] Repr of lambda

[Ivan Pozdeev]

On 17.12.2017 22:20, Serhiy Storchaka wrote:
> Currently repr of doesn't contain much of information besides that it 
> is a lambda.
>
> >>> lambda x: x**2
> <function <lambda> at 0x7f3479b74488>
>
> All lambdas have the same repr, different only by unreadable 
> hexadecimal address.
>
> What if include the signature and the expression of the lambda in its 
> repr?
>
> >>> lambda x: x**2
> <lambda x: x**2>
>
It's the same for named functions:

     In [1]: def ditto(a): return a

     In [2]: ditto
     Out[2]: <function __main__.ditto>

Are you intending to do the same for them?
> This would return an old feature of Python 0.9.1 
> (https://twitter.com/dabeaz/status/934835068043956224).
>
> Repr of function could contain just the signature.
>
> <function foo(bar, baz)>
>
> But there is a problem with default values. Their reprs can be very 
> long, especially in the following case with mutable default value:
>
> def foo(x, _cache={}):
>     try:
>         return _cache[x]
>     except KeyError:
>         pass
>     _cache[x] = y = expensive_calculation(x)
>     return y
>
> Maybe the placeholder should be always used instead of default values.
>
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-- 
Regards,
Ivan