# Number::Fraction

Th. J. van Hoesel th.j.v.hoesel at gmail.com
Fri May 3 10:43:05 BST 2013

```Op 3 mei 2013, om 10:21 heeft Dave Cross het volgende geschreven:

> Quoting "Th. J. van Hoesel" <th.j.v.hoesel at gmail.com>:
>
>> to me, it would make sense for 3 parameters:
>>
>> Number::Fraction->(int, num, den);
>>
>> but that would be helpful to work with the so called vulgar fractions and cold write things like:
>> my \$twothreefourth = Number::Fraction->new( 2, 3, 4);
>
> I think we're starting to get quite close to an area where positional parameters are potentially confusing.
>
>  Number::Fraction->new(1, 2); # num = 1, den = 2
>  Number::Fraction->new(1, 2, 3) # int = 1, num = 2, den = 3

Positional Parameters can be  a disaster, I know. But sticking to these THREE positional parameters max looks to me not impossible for the user. Also, Math::Fraction utilizes the same schema.

Basically it would do the things below

1 parameter ----> integer
and will be handled as @_[0] ÷ 1
2 parameter ----> fraction
will be handled as @_[0] ÷ @_[1]
3 parameter ----> mixed
will become { @_[0] × @_[2]   +  @_[1]  } ÷ @_[2]

and yes, that above is a bit nasty written, for there are quite a bit of 'exceptions' to handle --- and especially the 1-parameter version will have to deal with strings or references

>
> I would probably think seriously about using named parameters here
>
>  Number::Fraction->new(numerator => 1, denominator => 2);
>  Number::Fraction->new(integer => 1, numerator => 2, denominator => 3);

Bu t you will then have to invent a way to remain backward compatible an maintain both ways

> Of course, the fact that the names of the parameters are so long really counts against you here, so you'd want to allow aliases - int, den & num.
>
> In fact, it probably makes sense to move it all to Moose (or Moo, at least).

Noooooooo! it was so simple to use

>> can I drop other cases or do you prefer to allow method calls with unlimited number of parameters ???
>
> You need to deal with idiots who ignore the documentation and call the methods with the incorrect parameters. Currently, if you call new() with more than two parameters, the extra ones are just silently ignored. I think I like that option best, but I wouldn't object if the constructor just died instead.

I'd prefer to let anything die that does not comply with the supplied interface or API.

Yes, I know:
be tolerant to what to consume and be strict in what you produce

One thing I was a bit worried about is the fact you accept denominators equal to ZERO ---- Arghhh!. Although totally insane, it's not 'your' fault that division by zero is illegal. Let perl die because of that fact, not the Fraction Module.

> Cheers,
>
> Dave...
>
> p.s. This conversation would be much easier to follow if we all used the same quoting style :-/
>

better ? :-)
```