Re: Parsing of numeric values

Tuesday, September 15, 2009, 3:46:17 PM, wkbutler wrote:

> 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.

I don't know... it's not enough concrete for me to form an opinion.
The part that is a bit suspicious for me, that if the numerical output
generated by the 1st order macros meant to be treated as numbers by
the 2nd order macros, then why are they in human-audience format? I
mean, FM can output in computer-audience numerical format as well.

> 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?

There is a way (as far as using a global variable instead of
data-model variable is fine for you). Use something like this instead
of the myTemplate.process(root, out) call:

  Environment env = myTemplate.createProcessingEnvironment(root, out);
  env.setGlobalVariable("util",
      env.getObjectWrapper().wrap(new DataUtil()));
  env.process();

> 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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>

-- 
Best regards,
 Daniel Dekany


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