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Adjust subtraction to scale operands up, thereby avoiding the silly long results

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Craig Earls 2013-07-02 12:05:00 -07:00
parent 8da79a8967
commit a6cb179d8a
1 changed files with 8 additions and 2 deletions
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10
lisp/ldg-commodities.el
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@ -33,6 +33,10 @@
:type 'string :type 'string
:group 'ledger-reconcile) :group 'ledger-reconcile)
(defcustom ledger-scale 10000
"The 10 ^ maximum number of digits you would expect to appear in your reports.
This is a cheap way of getting around floating point silliness in subtraction")
(defun ledger-split-commodity-string (str) (defun ledger-split-commodity-string (str)
"Split a commoditized string, STR, into two parts. "Split a commoditized string, STR, into two parts.
Returns a list with (value commodity)." Returns a list with (value commodity)."
@ -81,7 +85,9 @@ Returns a list with (value commodity)."
(defun -commodity (c1 c2) (defun -commodity (c1 c2)
"Subtract C2 from C1, ensuring their commodities match." "Subtract C2 from C1, ensuring their commodities match."
(if (string= (cadr c1) (cadr c2)) (if (string= (cadr c1) (cadr c2))
(list (- (car c1) (car c2)) (cadr c1)) ; the scaling below is to get around inexact subtraction results where, for example
; 1.23 - 4.56 = -3.3299999999999996 instead of -3.33
(list (/ (- (* ledger-scale (car c1)) (* ledger-scale (car c2))) ledger-scale) (cadr c1))
(error "Can't subtract different commodities %S from %S" c2 c1))) (error "Can't subtract different commodities %S from %S" c2 c1)))
(defun +commodity (c1 c2) (defun +commodity (c1 c2)
@ -97,7 +103,7 @@ Returns a list with (value commodity)."
(setq new-str (append new-str (list ch)))))))) (setq new-str (append new-str (list ch))))))))
(defun ledger-string-to-number (str &optional decimal-comma) (defun ledger-string-to-number (str &optional decimal-comma)
"improve builtin string-to-number by handling internationalization, and return nil of number can't be parsed" "improve builtin string-to-number by handling internationalization, and return nil if number can't be parsed"
(let ((nstr (if (or decimal-comma (let ((nstr (if (or decimal-comma
(assoc "decimal-comma" ledger-environment-alist)) (assoc "decimal-comma" ledger-environment-alist))
(ledger-strip str ?.) (ledger-strip str ?.)