Originally asked this on SO but was redirected here.
I have a script that's asking the user to input a lot of dates, mostly in functions similar to the one below. These need to account for invalid date formats:
import numpy as np import pandas as pd import xlwings as xw import datetime as dtt def week_init(): """Creates an initial week datetime and determines what the checking cutoff 'beforeday' to be used in Stage 2 is.""" week = input('Week to check: MM/DD/YYYY\n') switch = 1 while switch == 1: try: week = dtt.datetime.strptime(week,'%m/%d/%Y') #turns input to a datetime switch = 0 except ValueError: #couldn't parse as a date MM/DD/YYYY week = input('Unrecognized date format, please try again: MM/DD/YYYY\n') beforeday = (input('Check days before date (Press enter to use today): MM/DD/YYYY\n') or dtt.date.today()) if (beforeday != dtt.date.today()): switch = 1 while switch == 1: try: beforeday = dtt.datetime.strptime(beforeday,'%m/%d/%Y') switch = 0 except ValueError: #couldn't parse as a date MM/DD/YYYY beforeday = input('Unrecognized date format, please try again: MM/DD/YYYY\n') return week, beforeday
There are also functions that check an index for a given date, and have to deal with a given date not matching any of the indices:
def spotmap(week, bam, pt): """Maps the pivoted data for the chosen week to the BAM dataframe's SD column.""" print('Mapping data to BAM... ',end=''), switch = 1 while switch == 1: try: bam['SD'] = bam.index.to_series().map(pt.fillna(0)['len',week]) switch = 0 except KeyError: #date doesn't match any of the pivot table's columns print('Invalid date, please try again.') week = input('Week start date (Sunday): MM/DD/YYYY\n') print('Done') return bam
As the script has a lot of things to do after it gets these dates, I don't want it to crash when it has a problem, but it can't proceed without correct date inputs so I currently have it looping with those "switch" variables controlling when it is willing to move on with a valid date. As you can see, though, these try/except blocks are rapidly bloating the otherwise straightforward code. Is there a way to condense these things? Also, a better method than the switches?
The answers here suggested decorators, but as far as I can tell from the documentation and pages like this, those are for wrapping functions, not for replacing interior code blocks. Also I'm not sure how useful they'd be, because the try/except blocks are mostly unique in what they're trying to accomplish (ie, which variable they're changing or whether they're checking against an index). I guess I'm really just hoping for some better general exception-handling syntax.