Hi,
We've run into an issue with using JEXL due to a combination of integer
division on integer values and narrowing of BigDecimals to Integer. Not sure if
this type of problem has come up before. This forum only seems to have 4 jexl
issues and the Jira didn't have anything similar either.
We use JEXL to allow our end users to write simple "Excel" like expressions.
All the numeric variables in our expressions are presented to JEXL as
BigDecimals.
The problem was exposed by the simple expression "(a-12)/12".
* If BigDecimal a = 56.1
* Then 56.1 - 12 -> BigDecimal 44.1
* Then BigDecimal 44.1 / 12 -> BigDecimal 44.1 / BigDecimal 12 ->
BigDecimal 3.675
* If BigDecimal a = 56
* Then BigDecimal 56 - 12 -> BigDecimal 44 -> narrows to Integer 44
* Then Integer 44 / Integer 12 -> Integer 3! Not 3.66666 recuring
(because division of integer values is done as integer division)
So the value of the result becomes incorrect based on the initial value of "a"
not it's type.
A work around is to change the expression to "(a-12)/12.0" to force Double
arithmetic, but that use of 12.0 isn't natural to ordinary users used to Excel.
Also if you had an expression like "(a-12)/(b-3)" you wouldn't have any way to
force the use of BigDecimal division instead of integer divisions as JEXL
chooses which based on the narrowed result value.
Also you could have a case of "a * (7/8)", e.g. 7 8ths of 'a' where the users
is more comfortable with expression 7/8 as a faction not a decimal. Here 7/8 ->
0 as integer division.
It would be useful if there was a way to:
* Force BigDecimal division not integer division
* Disable the narrowing to keep the intermediate and result types as
BigDecimal.
I haven't seem anything in the JexlArithmetic class that would allow the above.
Is there any other way to force this?
Kind regards,
Robert Lucas
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