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Experimental classes for controlling Float printing format

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Nicolas Cellier

Experimental classes for controlling Float printing format

Here is a set of experimental classes for controlling floating point
output format.
The ideas are:
- 1) we can extend these formatting capabilities without creating a
bunch of new messages combinations
instead, we just have parameterized FloatPrinter object (+
subclasses), and use cascade of elementary messages
The capabilities are right now limited to scientific, free
format, fixed point and storeOn: format.
But features are growable, and we could as well control
localization, thousand separators, padding (total width, width left of
fraction point, force + sign, etc...)
- 2) The complex algorithm for printing accurately
(Burger/Dybvig/Steele) has been split into private methods in order to
be reusable by various format (fixed number of decimal places and
fixed number of significand digits)
I choosed to store above algorithm internal states in inst var
in order to avoid explosion of meaningless parameters...
This turns the functional implementation into a stateful
implementation, but encapsulated in a class and private messages...
It's a bit the same design choice as SqNumberParser.
Having more comments is also a benefit (it's still preferable to
read the paper though)

The good news is that, despite parametrization and FloatPrinter
instantiation, slow down is typically limited to 3% (we can optimize
the default case eventually)...

Comments, extensions and alternate design are welcome.

Nicolas

Experimental.st (21K) Download Attachment

LawsonEnglish

Re: Experimental classes for controlling Float printing format

Take a look at the capabilities of the mpfr library. In the long run, it might be good to be able to switch between the boxed float primitive of squeak/pharo, and the extended capabilities of the external lib: http://www.mpfr.org/ and the capabilities of mpfr might be a good guideline for what an extended floating point class should be able to do.

Lawson

On 5/22/12 3:53 PM, Nicolas Cellier wrote:

Here is a set of experimental classes for controlling floating point
output format.
The ideas are:
- 1) we can extend these formatting capabilities without creating a
bunch of new messages combinations
      instead, we just have parameterized FloatPrinter object (+
subclasses), and use cascade of elementary messages
      The capabilities are right now limited to scientific, free
format, fixed point and storeOn: format.
      But features are growable, and we could as well control
localization, thousand separators, padding (total width, width left of
fraction point, force + sign, etc...)
- 2) The complex algorithm for printing accurately
(Burger/Dybvig/Steele) has been split into private methods in order to
be reusable by various format (fixed number of decimal places and
fixed number of significand digits)
      I choosed to store above algorithm internal states in inst var
in order to avoid explosion of meaningless parameters...
      This turns the functional implementation into a stateful
implementation, but encapsulated in a class and private messages...
      It's a bit the same design choice as SqNumberParser.
      Having more comments is also a benefit (it's still preferable to
read the paper though)

The good news is that, despite parametrization and FloatPrinter
instantiation, slow down is typically limited to 3% (we can optimize
the default case eventually)...

Comments, extensions and alternate design are welcome.

Nicolas

-- 
Squeak from the very start (introduction to Squeak and Pharo Smalltalk for the (almost) complete and compleate beginner).
https://www.youtube.com/playlist?list=PL6601A198DF14788D&feature=view_all

Colin Putney-3

Re: Experimental classes for controlling Float printing format

In reply to this post by Nicolas Cellier

On Tue, May 22, 2012 at 3:53 PM, Nicolas Cellier
<[hidden email]> wrote:

> Comments, extensions and alternate design are welcome.

I like the design a lot. Recently I've had occasion to implement a
couple of alternate integer printing implementations, and I found that
a separate printer object works nicely. It would also be handy for
non-invasive printing in the dev tools.

Colin

Nicolas Cellier

Re: Experimental classes for controlling Float printing format

In reply to this post by LawsonEnglish

2012/5/23 Lawson English <[hidden email]>:
> Take a look at the capabilities of the mpfr library. In the long run, it
> might be good to be able to switch between the boxed float primitive of
> squeak/pharo, and the extended capabilities of the external lib:
> http://www.mpfr.org/ and the capabilities of mpfr might be a good guideline
> for what an extended floating point class should be able to do.
>
> Lawson
>
>

http://www.mpfr.org/mpfr-current/mpfr.html#Formatted-Output-Functions
tells mpfr provides kind of printf.
That's the purpose of FloatPrinter experiments.

Nicolas

>
>
>
> On 5/22/12 3:53 PM, Nicolas Cellier wrote:
>
> Here is a set of experimental classes for controlling floating point
> output format.
> The ideas are:
> - 1) we can extend these formatting capabilities without creating a
> bunch of new messages combinations
> instead, we just have parameterized FloatPrinter object (+
> subclasses), and use cascade of elementary messages
> The capabilities are right now limited to scientific, free
> format, fixed point and storeOn: format.
> But features are growable, and we could as well control
> localization, thousand separators, padding (total width, width left of
> fraction point, force + sign, etc...)
> - 2) The complex algorithm for printing accurately
> (Burger/Dybvig/Steele) has been split into private methods in order to
> be reusable by various format (fixed number of decimal places and
> fixed number of significand digits)
> I choosed to store above algorithm internal states in inst var
> in order to avoid explosion of meaningless parameters...
> This turns the functional implementation into a stateful
> implementation, but encapsulated in a class and private messages...
> It's a bit the same design choice as SqNumberParser.
> Having more comments is also a benefit (it's still preferable to
> read the paper though)
>
> The good news is that, despite parametrization and FloatPrinter
> instantiation, slow down is typically limited to 3% (we can optimize
> the default case eventually)...
>
> Comments, extensions and alternate design are welcome.
>
> Nicolas
>
>
>
>
>
> --
> Squeak from the very start (introduction to Squeak and Pharo Smalltalk for
> the (almost) complete and compleate beginner).
> https://www.youtube.com/playlist?list=PL6601A198DF14788D&feature=view_all
>
>
>
>