Re: Parsing of numeric values

Thank you Daniel.  Makes sense, so I shall pursue another route.

To speak theoretically then... I did consider putting this logic into the
'C' part of MVC, but that breaks my use case.  This application allows the
user to define macros (happily implemented with FM) against a pool of data,
and to define macros using the output of other macros (2nd-order macros). 
Thus by definition, I have FM scripts that reference the output of other FM
scripts, which may possibly be mathematical expressions against formatted
numeric values.

A followup question...

In the past I have added custom processing methods by inserting a class
reference into the data Map given to the Template.process(..) method, i.e.

    data.put("util", new DataUtil());

however my data map these days is a Map<String,String> so this will not
work.  
Do I need to revert my dataset to a Map<String, Object>, or is there another
way to inject custom utilities?

Thanks again -



Daniel Dekany wrote:
> 
> Tuesday, September 15, 2009, 4:34:22 AM, wkbutler wrote:
> 
>>
>> Hello - 
>> I am a bit confused on the built-in capability of FM to parse a localized
>> numeric expression,
> 
> It's none. FM can convert simple "computer-audience number" strings
> back to numbers, because sometimes, for purely technical reasons, you
> get numbers "serialized" to text format. Parsing human-audience
> numbers is out of the scope of FM, and in theory you should deal with
> that in the C of MVC, not in the V. Means, although you can solve that
> in the V with a TempateMethdoModelEx (or with a #function), you might
> shouldn't do that.
> 
>> and before I write a custom routine for this, maybe
>> there is wisdom I lack.
>>
>> I am trying to process a mathematical expression on the contents of a map
>> of
>> string data:
>>
>> ---------------
>> | a |  1,111    |
>> | b |  2,222    |
>> ---------------
>>
>> so a simple expression like
>>      ${a?number + b?number}  
>>
>> would work if the numbers were not localized, right?
> 
> At least with this concrete example, yes.
> 
>> That I have had success with.
>>
>> The original syntax 
>>    #{a} + #{b}
>>
>> is deprecated according to this page in the docs
>>     
>> http://freemarker.sourceforge.net/docs/ref_depr_numerical_interpolation.html
> 
> It is. Don't use it.
> 
>> although trying this I get the error message:
>>
>>     a is not a number, it is freemarker.template.SimpleScalar
> 
> Unlike ?number, #{...} doesn't even try to convert strings to numbers.
> 
>> Using the number built-in ?c and the string built-in
>> ?string.computer fail with similar messages,
> 
> These convert a number (or date, etc.) to a string, not the other way
> around.
> 
>> such as "Expected hash" etc. It seems I do not understand what data
>> type I am dealing with.
> 
> notANumber?string is not a hash (aNumber?string is), but the dot (.)
> operator will expect a hash on its left side, hence it throws the
> above error. Yeah, a but tricky...
> 
>> I would like to have have the 2 numbers added together and output with
>> the
>> default localized syntax.  Am I looking past something?
> 
> No, except maybe that, whatever view technology are you using
> (FreeMarker or not) it's not something that you should do in a the
> view layer of your application. At least usually it's not...
> 
>> Thanks for ideas
> 
> -- 
> Best regards,
>  Daniel Dekany
> 
> 
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