Keeping a list of records with named fields that can be updated

[Weatherby,Gerard]

I have a lot of NamedTuples in my codebase, and I now add new ones never. They were a good option prior to Python 3.7 but dataclasses are much easier to work with and are almost a drop-in substitute.

A combination of a default dictionary and a dataclass might meet your needs:



import collections
from dataclasses import dataclass


@dataclass
class AccountingEntry:
    description: str
    # other fields


ledger = collections.defaultdict(list)

for ae in get_accounting_entries():
    ledger[ae.description] = ae



From: Python-list <python-list-bounces+gweatherby=uchc.edu at python.org> on behalf of songbird <songbird at anthive.com>
Date: Wednesday, December 14, 2022 at 10:38 PM
To: python-list at python.org <python-list at python.org>
Subject: Keeping a list of records with named fields that can be updated
*** Attention: This is an external email. Use caution responding, opening attachments or clicking on links. ***

  I'm relatively new to python but not new to programming in general.

  The program domain is accounting and keeping track of stock trades and other related information (dates, cash accounts, interest, dividends, transfers of funds, etc.)

  Assume that all data is CSV format.  There are multiple files.

  Assume there is a coherent starting point and that all data is in order.

  Assume each line contains a description.  The description determines what the line is.  The number of fields in the line does not change within the data file but it may happen that later lines in other files may be different other than the fact that they all must contain a description.

  All descriptions are deterministic (none are recursive or referencing things from the future).  All things referenced in the description which do not already exist are added to a list (or perhaps more than one in a few cases) and may contain some basic information (the date, how many and for how much, or a total amount or a fee or ...)  If the field of the line isn't a number it is either a symbol or a description.

  A default action is simply to keep most parts of the line and to adjust any totals of a previously seen description that matches by whatever amounts are on the line.  The key is the description.

  I've already written one program based upon the files I already have which works but what happens is that new descriptions are added (new accounts, new stocks, etc.) and I don't want to have to write new code manually every time a description changes.

  I started using named tuples (it works for reading in the files and accessing the fields) but I cannot update those so I need to use something else to give me the list of unique descriptions and fields that I need to update.  I've not gotten beyond that yet as I'm still learning.

  Suggestions?

  Thanks!  :)


  songbird
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