Trying a custom handler for several math fields

[Richard Gaskin]

You could further that separation between display values and actual 
values with getProp and setProp, but I almost never use those because 
they're affected by lockMessages,

Would it be useful to be able to declare some getProp/setProp messages 
as always active, so they could be as immune to lockMessages as built-in 
properties are?

If so, what should that look like?

--
  Richard Gaskin
  Fourth World
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Mark Wieder wrote:
> Vaughn-
>
> Sunday, September 15, 2013, 12:40:03 PM, you wrote:
>
>>    put fld "Loan1" + fld "Loan2" into fld "Loan Balance"
>>    put fld "Vehicle Selling Price" - fld "Buyers Offer Discount" into fld
>> "Net Offer Price"
>>    put fld "Net Offer Price" + fld "Buyers Options Cost" - fld "Factory
>> Allowance" into fld "Sum of Offer"
>>    put fld "Sum of Offer" - fld "Buyers Accepted Trade" into fld "Net Amt
>> after Payoff"
>>    put fld "Net Amt after Payoff" - fld "Buyers Down PMT." into fld
>> "Balance Before Finance"
>>    put fld "Balance Before Finance" + fld "Tax" + fld "Plates" + fld "Doc
>> Fees" + fld "Options Other" into fld "Amount of Loan"
>>    put fld "Loan Term in Months" * fld "Monthly Payment" into fld "Sum of
>> Loan at Term"
>>    put fld "Amount of Loan" - fld "Sum of Loan at Term" into fld "Interest
>> Paid at Term"
>
> This is not how I would approach this, primarily because of the
> problem, as you have noted, of having to convert back and forth
> between the displayed dollar sign and the calculation values. Rather,
> I would separate out the business logic that does the calculations
> from the presentation logic that displays the results. Using your
> example above, that would come out something like
>
> -- strip any formatting characters
> function AmountOf pTextFromField
>   replace "$" with empty in pTextFromField
>   replace "," with empty in pTextFromField
>   return pTextFromField
> end AmountOf
>
> function Currency pNumber
>   put "$" before pNumber
>   return pNumber
> end Currency
>
> -- get the user input
> put AmountOf(field "Loan1") into tLoan1
> put AmountOf(field "Loan2") into tLoan2
> put AmountOf(field "Vehicle Selling Price") into tVehicleSellingPrice
> put AmountOf(field "Buyers Offer Discount") into tBuyersOfferDiscount
> put AmountOf(field "Buyers Accepted Trade") into tBuyersAcceptedTrade
> put AmountOf(field "Buyers Down PMT") into tBuyersDownPMT
> put AmountOf(field "Tax") into tTax
> put AmountOf(field "Plates") into tPlates
> put AmountOf(field "Doc Fees") into tFees
> put AmountOf(field "Options Other") into tOptionsOther
> put AmountOf(field "Loan Term In Months") into tLoanTermInMonths
> put AmountOf(field "Monthly Payment") into tMonthlyPayment
>
> -- do the calculations
> put tLoan1 + tLoan2 into tNetOfferPrice
> put tVehicleSellingPrice - tBuyersOfferDiscount into tNetOfferPrice
> put tNetOfferPrice + tBuyersAcceptedTrade into tNetAfterPayoff
> put tNetAfterPayoff - tBuyersDownPMT into tBalanceBeforeFinance
> put tBalanceBeforeFinance + tTax + tPlates + tFees + tOptionsOther \
> into tAmountOfLoan
> put tLoanTermInMonths * tMonthlyPayment into tSumOfLoanAtTerm
> put tAmountOfLoan - tSumOfLoanAtTerm into tInterestPaidAtTerm
>
> -- now display the formatted output
> put Currency(tNetOfferPrice) into field "Net Offer Price"
> put Currency(tSumOfOffer) into field "Sum of Offer"
> put Currency(tNetAfterPayoff) into field "Net Amount after Payoff"
> put Currency(tBalanceBeforeFinance) into field "Balance Before Finance"
> put Currency(tAmountOfLoan) into field "Amount of Loan"
> put Currency(tSomeOfLoanAtTerm) into field "Sum of Loan at Term"
> put Currency(tInterestPaidAtTerm) into field "Interest Paid at Term"