[Tutor] How to type annotate complex dictionary containing lambdas?

[DL Neil]

On 18/11/19 8:12 AM, boB Stepp wrote:
> On Sun, Nov 17, 2019 at 2:52 AM Alan Gauld via Tutor <tutor at python.org> wrote:
>> On 17/11/2019 05:32, boB Stepp wrote:
>>> My best effort so far to type annotate the dictionary below is to use

>> To be honest I wouldn't even be trying I'd be more concerned with
>> getting rid of such a messy dict and replacing it with a class.
>>
>> Type hints are no substitute for clean code.
> 
> Chastisement taken, accepted and fully merited!

+1

So, as you later allude, the *first* problem was the lack of tests...


> As I was staring at this program last night I was trying to recreate
> in memory its history of "development" (Ha!).  Originally it was an
> extremely short program with no comments, no docstrings, no input
> validation.  It was just a quick and dirty throw-away program to
...
> really was curious how such a beast would be properly type annotated.

...which led to the second problem, not so apparently recognised: that 
whilst this situation is common, in the spirit of 
learning-by-experimentation ("constructivism") and insatiable curiosity, 
we end-up with fairly-messy code. During 'the grand experiment' it was 
finally wrangled into some semblance of working code; and we moved-on.

However, in coming back to it, the realisation of today's superior 
knowledge and capability should be turned-into a re-factored and 
improved version of the existing code. Thereafter, today's experiment 
will build upon a more stable foundation!
(else, some risk that today's learning-mistakes are actually 
side-effects from time-before)


> One thing that trying to write tests has taught me:  If it is
> difficult to write tests for whatever, then something probably needs
> to be refactored/done better. 

+1


As you might guess, I did not write any
> tests for this program.  And apparently type annotations teach a
> similar sort of wisdom:  If it is hard to figure out how to annotate a
> given block of code, something really, really stinks!

+1

and yes, +1 on the class-upgrade (gives more leg-room on the plane!). We 
keep the dictionary structure and add (more flexible) functionality.

[oops, in saying that, I fear @Alan will come-after me: So, in a bid to 
prevent the tooth- and claw-marks: a class *first* gives function and 
*then* offers us a dictionary/data-structure 'for free' (sound of 
running footsteps to be heard, leaving stage right, rapidly)...]

-- 
Regards =dn