[GNC-dev] New balsheet (and P&L report), API considerations, and (slow?) KVP in Account.cpp

[Christopher Lam]

Hi All

I'm working through balance-sheet.scm and overhauling this report.

At the same time, I can see that balance-sheet.scm and 
income-statement.scm can be merged together.

After all

  * balance sheet = asset/liability/equity balance at date X,
  * income statement = difference in income/expense balances at date X and Y

The issue I have is that the balance sheet can call 
xaccAccountGetBalanceAsOfDate(acc,date) directly to nicely retrieve the 
balance, whereas income statement cannot directly call it because it 
also includes closing transactions.

My proposal is to augment xaccAccountGetBalanceAsOfDate to accept a 3rd 
boolean argument i.e. 
xaccAccountGetBalanceAsOfDate(acc,date,ignoreclosing) which will 
selectively produce the balance, ignore closing transactions.

This is partly done in the last commit of 
https://github.com/christopherlam/gnucash/tree/maint-create-API-call-for-noclosing-balances 
- it will augment API everywhere, and also modify Account.cpp, 
especially xaccAccountRecomputeBalance which will call 
xaccTransGetIsClosingTxn(xaccSplitGetParent(split)) for each split in 
the account to determine closing status and cache the balances for each 
split. See draft on 
https://github.com/christopherlam/gnucash/tree/maint-create-API-call-for-noclosing-balances 
- this currently fails because I'm not good at C.

*My query is whether it will be too expensive to call 
xaccTransGetIsClosingTxn for each split in Account.cpp to produce the 
split->noclosing_balance, which will be crucial to calculate income 
between two dates.*

*Currently this 'closing-txn' filter is done in income-statement.scm via 
a "Closing Entries" string/regex filter and xaccTransGetIsClosingTxn 
calls, which IMHO is not ideal either.
*

Any help welcome!

P.S. if this last commit is removed, the 
https://github.com/christopherlam/gnucash/tree/maint-create-API-call-for-noclosing-balances 
branch contains work-so-far for updated balance-sheet. Screenshot 
https://screenshots.firefox.com/eelmGQrGCtcP6bqC/null - see the 
multilevel subtotals were previously horizonal, are now vertical; 
original-currency amounts, and multiple-date balance sheets.