The payment amount must be greater than zero

Patrik Lermon patrik at
Mon Aug 20 05:13:54 EDT 2007

On 8/20/07, Derek Atkins <warlord at> wrote:
> Quoting Graham Leggett <minfrin at>:
> > Derek Atkins wrote:
> >
> >> Unfortunately it's not THAT simple.  From the UI, yes, but there are
> >> underlying assumptions that the UI is helping enforce.  Entering a
> >> negative amount would break those underlying assumptions.
> >
> > What underlying assumptions? All cashflows can flow in either
> > direction for any number of reasons, the software shouldn't stop
> > figures being negative, that's the user's job, should the user choose
> > to.
> Underlying assumptions in the business features that Invoices are always
> on sign and Payments are always the other.  A negative payment would
> therefore look like an Invoice..  but it's NOT an invoice.. And it would
> confuse the payment-merging processing for handling over/under-payments
> across multiple invoices.
> Feel free to look at src/business/business-core/gncInvoice.c if you want
> to try to come up with a better approach.
> > Regards,
> > Graham
> -derek
> --
>        Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
>        Member, MIT Student Information Processing Board  (SIPB)
>        URL:    PP-ASEL-IA     N1NWH
>        warlord at MIT.EDU                        PGP key available

I think that assumption is actually wrong.
I mean, credit invoices are a rather common way to solve when you accidentally
invoiced someone, or invoiced the wrong amount etc.


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