=begin pod :kind("Type") :subkind("class") :category("basic")

=TITLE class NumStr

=SUBTITLE Dual value floating-point number and string

    class NumStr is Num is Str { }

The dual value types (often referred to as L<allomorphs|/language/glossary#Allomorph>)
allow for the representation of a value as both a string and a numeric type. Typically
they will be created for you when the context is "stringy" but they can be determined
to be numbers, such as in some L<quoting constructs|/language/quoting>:

    my $f = <42.1e0>; say $f.^name; # OUTPUT: «NumStr␤»

As a subclass of both L«C<Num>|/type/Num» and L«C<Str>|/type/Str», a C<NumStr>
will be accepted where either is expected. However, C<NumStr> does not share
object identity with C<Num>- or C<Str>-only variants:

    my $num-str = <42e10>;
    my Num $num = $num-str; # OK!
    my Str $str = $num-str; # OK!
    say 42e10 ∈ <42e10  55  1>; # False; ∈ operator cares about object identity

=head1 Methods

=head2 method new

    method new(Num $i, Str $s)

The constructor requires both the C<Num> and the C<Str> value, when constructing one
directly the values can be whatever is required:

    my $f = NumStr.new(42.1e0, "forty two and a bit");
    say +$f; # OUTPUT: «42.1␤»
    say ~$f; # OUTPUT: «"forty two and a bit"␤»

=head2 method Bool

Defined as:

    multi method Bool(NumStr:D: --> Bool:D)

I<This method may be provided by the parent classes and not implemented in NumStr directly>.

Returns C<False> if the invocant is numerically C<±0e0>, otherwise returns C<True>. String portion
is not considered.

=head2 method Num

    method Num

Returns the C<Num> value of the C<NumStr>.

=head2 method Numeric

Defined as:

    multi method Numeric(NumStr:D: --> Num:D)
    multi method Numeric(NumStr:U: --> Num:D)

The C<:D> variant returns the numeric portion of the invocant. The C<:U> variant issues
a warning about using an uninitialized value in numeric context and then returns value C<0e0>.

=head2 method Real

Defined as:

    multi method Real(NumStr:D: --> Num:D)
    multi method Real(NumStr:U: --> Num:D)

The C<:D> variant returns the numeric portion of the invocant. The C<:U> variant issues
a warning about using an uninitialized value in numeric context and then returns value C<0e0>.

=head2 method Str

Returns the string value of the C<NumStr>.

=head2 method ACCEPTS

Defined as:

    multi method ACCEPTS(NumStr:D: Any:D $value)

If C<$value> is L<Numeric|/type/Numeric> (including another
L<allomorph|/language/glossary#index-entry-Allomorph>), checks if invocant's
L<Numeric|/type/Numeric> part L<ACCEPTS|/type/Numeric#method_ACCEPTS> the C<$value>. If
C<$value> is L<Str|/type/Str>, checks if invocant's L<Str|/type/Str> part
L<ACCEPTS|/type/Str#method_ACCEPTS> the C<$value>. If value is anything else,
checks if both L<Numeric|/type/Numeric> and L<Str|/type/Str> parts C<ACCEPTS> the C<$value>.

    say <5e0> ~~ "5.0"; # OUTPUT: «False␤»
    say <5e0> ~~  5.0 ; # OUTPUT: «True␤»
    say <5e0> ~~ <5.0>; # OUTPUT: «True␤»

=head1 Operators

=head2 infix cmp

    multi sub infix:<cmp>(NumStr:D $a, NumStr:D $b)

Compare two C<NumStr> objects.  The comparison is done on the C<Num> value first and
then on the C<Str> value. If you want to compare in a different order then you would
coerce to a C<Num> or C<Str> value first:

    my $f = NumStr.new(42.1e0, "smaller");
    my $g = NumStr.new(43.1e0, "larger");
    say $f cmp $g;          # OUTPUT: «Less␤»
    say $f.Str cmp $g.Str;  # OUTPUT: «More␤»

=end pod

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