[Pharo-dev] About SqNumberParser

Nicolas Cellier nicolas.cellier.aka.nice at gmail.com
Mon Oct 28 14:46:42 EDT 2013


Concerning FORTRAN, I think it was removed for a long time, it was just an
example of how the NumberParser could be used.
Concerning the ExtendedNumberParser, I find it useful to have it, because
it can parse inputs like:
+1.4
-1.2e+3
.005
127.e6
A lot of languages/applications around the world would accept these as
valid Number.
Smalltalk syntax is much stricter...

OK, it's just a DSL, and it could as well be implemented by other means...
Whether such DSL implementation belongs to NumberParser hierarchy or not,
is a choice that was guided by 2 things
- NumberParser provides an implementation that will correctly round the
number to nearest Float (or ScaledDecimal eventually)
  I've seen too many Smalltalk implementations departing from universal
standards with this respect (IOW, wrong)
- NumerParser tries to be efficient (as far as Smalltalk can be),
especially in the cases with many digits
The first point is mandatory.
The second is just an optimization.

Now that you have more insight about rationale which guided those
decisions, it's up to you :)

Cheers

Nicolas



2013/10/28 Marcus Denker <marcus.denker at inria.fr>

>
> On 28 Oct 2013, at 17:55, Yuriy Tymchuk <yuriy.tymchuk at me.com> wrote:
>
>
> On 28 Oct 2013, at 17:49, Marcus Denker <marcus.denker at inria.fr> wrote:
>
>
> On 28 Oct 2013, at 10:41, Yuriy Tymchuk <yuriy.tymchuk at me.com> wrote:
>
> So what we decide to do with this?
>
> I  can work on that case, but I have 2 questions:
>
> - do we care to provide parsing of numbers in other notations as Pharo one?
>
>
> That’s a good question.. I completely misunderstood the code there because
> that sounds a bit
> strange that a language supports other languages syntax, but not “inside”
> the language but somehow as a tool…
>
> I fear that even if someone needs Fotran number parsing, the last place to
> look would be the Pharo base kernel
> classes…
>
>
> There are 2 extremes here. If you want to parse a fortran number, you
> probably also want to parse other fortran parts, and so you have some
> dedicated parser.
> But if you want to just parse some general number and it’s +2, then you
> can’t easily do that.
>
>
> - what is the number syntax that we want to support?
>
> Yes, we we need to document it. Right now it is “some extended Squeak
> format” which is just defined by the implementation.
>
>
> I can levee the implementation that is used now (a sq one). Or use
> extended. But it should be really nice to think about what we want to have
> instead of what we can use.
>
>
> If we have to decide, we should take the simple path. The fact that I am
> completely confused about this is not a good sign (maybe more related to my
> intelligence… :-)
>
> Marcus
>
>
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