[Newbies] Number formatting printf/sprintf for Squeak?

[Lukas Renggli]

Seaside 2.9alpha2 (builder.seaside.st) has a sophisticated framework
to build formatting objects. On of the tests for example look like
this, but there is much more that you can do:

testSwissCurrency
	| printer |
	printer := WASequentialPrinter new , 'CHF ' , WASignPrinter new ,
(WANumberPrinter new separator: $'; precision: 2; accuracy: 0.05;
yourself).
	
	self assert: (printer print: 12.34) = 'CHF 12.35'.
	self assert: (printer print: -12.39) = 'CHF -12.40'

Cheers,
Lukas

On Mon, Feb 16, 2009 at 11:44 PM, Michael van der Gulik
<mikevdg at gmail.com> wrote:
>
>
> On Tue, Feb 17, 2009 at 10:44 AM, Sorensen <sorens at surfy.net> wrote:
>>
>> Is there a printf/sprintf-like package for formatting text  for Squeak?
>>
>> If not, how do Squeakers go about formatting currency amounts or left
>> justifying text within a field?
>
>
> My initial reaction was "that's obvious; there are methods in the String
> class", but when I looked I realised that this isn't actually as trivial as
> that.
>
> For printf-like functionality, class String has a "formatting" category with
> undocumented methods. The excellent "Squeak by Example" book has some
> examples (http://scg.unibe.ch/SBE/SBE.pdf, page 208) but the functionality
> is very limited compared with printf.
>
> See also SequenceableCollection>>copyReplaceAll:with:
>
> For formatting currency, I notice there's a Locale class with
> Locale>>primCurrencySymbol, but I can't find any more advanced methods for
> actually formatting a currency, and I can't find any currency classes for
> any Smalltalk dialect on Google (!), apart from an LcMonetary class for GNU
> Smalltalk.
>
> For left-justifying text, I'm a bit surprised that you'd want to do this.
> Typically, you'd make the text left or right justified in whatever GUI
> element that value ends up in, rather than padding it with spaces.
>
> Anyway; some code examples for actually doing the above:
>
> Formatting a currency (specifically in my Locale) with two decimal places:
>
> " I assume that you're using ScaledDecimals for the currency; you generally
> shouldn't use Floats for currency. "
> c := ScaledDecimal newFromNumber: 123.45 scale: 2.
> " It's good practise to use a stream for formatting strings manually "
> stream := WriteStream on: (String new: 30).
> c >= 0 ifTrue: [ stream nextPut: $- ].
> stream nextPutAll: Locale current primCurrencySymbol. " Generally, prim
> methods should be private... "
> c printOn: stream. " Bug: also prints out 's2'. "
> result := stream contents.
>
> I would also add a new method to ScaledDecimal to print out its value
> without appending an 's2'. In fact, I'd probably make a subclass of Number
> or ScaledDecimal called "Currency" and release it as a reusable package.
>
> Left-justifying text with padding:
>
> padding := String new: 40.
> padding replaceAll: (Character value: 0) with: $ .
>
> s := 'format me'.
> result := padding copy replaceFrom: 1 to: s size with: s.
>
> Gulik.
>
>
> --
> http://people.squeakfoundation.org/person/mikevdg
> http://gulik.pbwiki.com/
>
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>



-- 
Lukas Renggli
http://www.lukas-renggli.ch