RE: [office-formula] Expression Calculation: expression = formula?

["Dennis E. Hamilton" <dennis.hamilton@acm.org>]

There's a place in Part 2 that makes a normative statement considering "="
and the optional recalculate "=" also being part of the OpenFormula Formula.
(I don't have it at hand at the moment.)

 - Dennis

FORMAT ARCHEOLOGY THOUGHTS:

What I think is interesting, from a computer folklore perspective, is that,
historically, the leading "=" was (and is) a UI device for an user
specifying that a formula was being entered rather than a text value or some
other value (a number, a date, whatever) that it might otherwise resemble.
There is also usually a convention for forcing text (e.g., that begins with
= or that looks like a number or an expression but isn't intended to be
interpreted as such).  I don't recall with certainty whether the convention
applies in CSV files or not.  I think not.

These are all UI dialog conventions.  In a document format, the value in a
separate attribute that holds only formulas doesn't need the prefix (we know
it is a formula at this level), and indeed if you look at the SpreadsheetML
of OOXML documents, those markers do not appear in the formula attribute
values, but they are still used in the Excel UI.

I have no idea how the "=" got into the definition of the ODF 1.0
table:formula attribute, and how it ended up being a matter of importance
for OpenFormula.  But it is there now. 

I HAVE FOUND A GREAT USE FOR THE = FORM.  In plaintext, including JIRA, I
use the =(expression) form to signify I am typing OpenFormula, and mean the
computational value that expression determines, not a mathematical
expression and its mathematical result.  If we take it out, I'll have to
come up with something else [;<).

  

-----Original Message-----
From: robert_weir@us.ibm.com [mailto:robert_weir@us.ibm.com] 
Sent: Tuesday, January 26, 2010 10:04
To: dennis.hamilton@acm.org
Cc: 'office-formula'; 'Patrick Durusau'
Subject: RE: [office-formula] Expression Calculation: expression = formula?

Question:  is the '=' essential for OpenFormula?  In other words, is is 
used for all uses of formulas?  Or is it something specific to the 
table:formula attribute in Part 1?

-Rob


"Dennis E. Hamilton" <dennis.hamilton@acm.org> wrote on 01/26/2010 
12:19:27 PM:
> 
> My understanding is that formula is the super class in the send that it
> allows any expression to the right of the "=".  That expression becomes 
the
> whole expression of the formula.
> 
> The syntactic definition should make this clear.  There should be 
nothing in
> the syntax for expression that has a constituent named formula.
> 
>  - Dennis 
> 
> -----Original Message-----
> From: Patrick Durusau [mailto:patrick@durusau.net] 
> Sent: Tuesday, January 26, 2010 07:41
> To: robert_weir@us.ibm.com
> Cc: office-formula
> Subject: Re: [office-formula] Expression Calculation: expression = 
formula?
> 
> Rob,
> 
> robert_weir@us.ibm.com wrote:
> > Patrick Durusau <patrick@durusau.net> wrote on 01/23/2010 10:20:48 AM:
> > 
> >> I am trying to work out a normative statement from current 2.2 
> >> Expression Calculation.
> >>
> >> I stumble over sentences like: "Any formula is an expression that 
> >> produces a result."
> >>
> >> So, is an expression that doesn't produce a result not a formula?
> >> 
> >
> > I guess the question is: Is this intended to be a definition or a 
> > constraint?
> >
> > The definition of "formula" ought to be done in terms of match a 
> > non-terminal identifier in the BNF grammar.  In other words, it is 
defined
> 
> > syntactically.
> >
> > If it is meant to be a constraint then it is a constraint on the 
Evaluator
> 
> > (formula processor) not the formula itself. 
> >
> > 
> I am not sure why it appears under 3 Types but the opening line of 3.1 
> General says:
> 
> > OpenFormula expressions, including formulas, always produce a value.
> >
> I read the relationship between expressions and formulas to be the one 
> Dennis points out, that any expression prepended by one or two "=" signs 

> is a formula. And matches the formula BNF. Anything that matches the 
> expression production but not prepended by one or two "=" signs is an 
> expression.
> 
> What is confusing is that the text appears at points to treat 
> expressions as a superclass that includes all formulas.
> 
> Actually I think they are distinct classes by definition.
> 
> To restate the opening sentence of 3.1 (assuming it were placed 
> somewhere else in the document):
> 
> "Evaluation of OpenFormula expressions and formulas shall produce a 
value."
> 
> Whether we want that as a constraint on evaluators is another question.
> 
> Hope you are having a great day!
> 
> Patrick
> 
> 
> 
> 
> 
> > -Rob
> >
> > 
> >> Or are the terms expression and formula meant to be interchangeable 
in 
> >> all cases?
> >>
> >> My operating assumption is that they are equivalent.
> >>
> >> So, why not just pick one? I am indifferent to which one.
> >>
> >> I have several questions but will separate them for clarity's sake.
> >>
> >> Hope everyone is having a great weekend!
> >>
> >> Patrick
> >>
> >> -- 
> >> Patrick Durusau
> >> patrick@durusau.net
> >> Chair, V1 - US TAG to JTC 1/SC 34
> >> Convener, JTC 1/SC 34/WG 3 (Topic Maps)
> >> Editor, OpenDocument Format TC (OASIS), Project Editor ISO/IEC 26300
> >> Co-Editor, ISO/IEC 13250-1, 13250-5 (Topic Maps)
> >>
> >>
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> >>
> >> 
> >
> >
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> >
> >
> > 
> 
> -- 
> Patrick Durusau
> patrick@durusau.net
> Chair, V1 - US TAG to JTC 1/SC 34
> Convener, JTC 1/SC 34/WG 3 (Topic Maps)
> Editor, OpenDocument Format TC (OASIS), Project Editor ISO/IEC 26300
> Co-Editor, ISO/IEC 13250-1, 13250-5 (Topic Maps)
> 
> 
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