Add support of metric numeral expression. fixes #456

[aloisdg]

Hello,

I created the PR because this is a full working draft. I would be glad to get any kind of reviews.
This is my first time with xUnit (coming from NUnit and MsTest). Any help is welcome!

Features:

• Convert from metric numeral expression (double only)
• Convert to metric numeral expression (double only)
• Add int support
• Support all symbols (decimal include)
• Support the name of each symbols (see List of SI prefixes) (partial => export is supported)
• Support the name of each symbols (see List of SI prefixes) (partial => import is supported)
• Handle space between number and symbol
• Add ByteSize's similar syntax
• Add the choice of precision
• Add the support of small symbol / name (this include a switch from char to string in symbols because of deca "da"). Full list : { hecto, h, 1E+2 }, { deca, da, 1E+1 }, { deci, d, 1E-1 }, { centi, c, 1E-2 }. This feature will be lock by default. A boolean in parameter will unlock it.

Also:

• Up-to-date and complete XML documentation
• Include unit tests
• Include unit tests with exception coverage

cheers,

[aloisdg]

I don't know if I want to switch or to add ByteSize Syntax. I created this extensions with a syntax near the one from RomanNumeral in mind. Should I do the move? Is it worth it?

If I switch to the OOP, it will allow devs to use operator overloading for example. If It would be nice to have the possibility to use it, I think it is better to use only the basic double number and to keep this methods only for I/O with the user. Any counter-example?

[aloisdg]

For the choice of precision, I am thinking about two ways:

• Full format support:

public static string ToMetric(this double input, string format,
    bool isSplitedBySpace = false, bool useSymbol = true)
{
    // ...

    return number.ToString(format)
        + (isSplitedBySpace ? " " : String.Empty)
        + GetUnit(symbol, useSymbol);               
}

• Precision only support:

public static string ToMetric(this double input, int n,
    bool isSplitedBySpace = false, bool useSymbol = true)
{
    // ...

    return number.ToString("#." + new string('#', n); // n is the count of numbers
        + (isSplitedBySpace ? " " : String.Empty)
        + GetUnit(symbol, useSymbol);               
}

Also

[aloisdg]

I think about switching from optional parameters to using overloads methods. I find it easiest to deal with this in public API. Is there any guidance around this in Humanizer? By the way, is there a StyleCop file (or alternative) for the project?

more reading : 1 2

[clairernovotny]

One favor -- Would you be able to rebase this onto the dev branch? If at all possible, it'd a big help.

How's this looking from a completion perspective otherwise, is it ready for review?

Thanks!

[clairernovotny]

Actually, nm...I'll handle the merge into dev when you're ready. Don't worry about it. Just let me know when you're ready. Thanks!

[aloisdg]

Ok thank you for the help. For now, everything works (AFAIk). I think I will let the support of e < 3 open. If someone want it, just create it. For the two others unchecked features, I would love some advices. I think it is a matter of preference.

[clairernovotny]

I've rebased this PR onto https://github.com/MehdiK/Humanizer/tree/aloisdg-metric for review

[aloisdg]

Nice. Thanks.

[clairernovotny]

I've merged this in to the dev branch. Thanks for your contribution!