So I'm -1 to putting it in the main branch of the src/org/apache/poi/hssf package unless its a full implementation but I've no particular objection to putting it in the scratchpad. I want to start seeing that as a bit more of a default case for new features that aren't 100%.
I'm +1 to adding plugs and hooks to hook in evaluation engines.
The HWPF experience has lead me to want to raise the bar for scratchpad contributions as well. Contrib/scratchpad should be "non-core" and "partially-implemented" stuff respectively. However, implemented features must have Javadoc, testcases and reasonable documentation. It has become clear to me that stuff will never stabilize and leave the scratchpad unless these standards are present and enforced.
so if we can integrate this code under those conditions, I think it will make a fine addition.
-Andy
[EMAIL PROTECTED] wrote:
tho I'm personally happy to see POI just as a file format reader... well, as
you'd have noticed, its often requested. So yeah, I'd be interested in seeing
this.
My concerns would be first that this have adequate documentation and unit tests.
I think that is paramount in functionality of this nature (and shouldnt be
difficult to test, either)
Also, I wonder what kind of API would be appropriate for this functionality.
One, since it is impossible to implement ALL excel functions immediately, the
code should degrade gracefully, while at the same time provide enuf feedback to
the called. Also, I would therefore like that adding new implementations of
functions should be easy.
I would also prefer if the math implementation could be pluggable.. if someone
were to want to integrate with pre-built math libraries in the future.
But in any case, lets see what you have. I am happy to have this added so long
as there are sufficient tests and docs.
Quoting Amol Deshmukh <[EMAIL PROTECTED]>:
I wanted to know if any work has been done for providing formula evaluation
functionality in POI. (I realise that POI is basically a file-format
translator, but such a utility could be useful when reading from files.)
If there has been no work done so far wrt formula evaluation and it is
deemed a useful feature, I would like to contribute my solution for this. I
have a partially implemented solution (based on FormulaParser and *Ptg
classes) that works for most common formulas with limited function support
(although thats only because I havent had the time to implement all std
excel functions, not a limitation of the approach per se). What is the best
way to submit this code for evaluation (no pun intended :)?
Regards, ~ amol
Notes:
Brief description of approach:
1. added function: "abstract Ptg evaluate(Ptg[] operands)" to OperationPtg
and implemented it in every concrete operation class.
2. Used FormulaParser to get RPN tokens from FormulaString and using simple
stack operations called evaluate on an operation token.
3. Functions are implemented as individual classes each having a "Ptg
evaluate(Ptg[] operands)" method.
4. All above operations are driven by FormulaEvaluator which also performs
evaluation of AreaPtg and ReferencePtg before invoking operations or
functions.
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