🚀 go-pugleaf

In article <47dn87$a17@sunsystem5.informatik.tu-muenchen.de>,
schuenem@informatik.tu-muenchen.de (Ulf Schuenemann) writes:
|> In article <46vaga$dng@marina.cinenet.net>, scotty@cinenet.net (J Scott
|> Peter XXXIII I/III) writes:
|> |> a += b	=>  a = a + b
|> |> a + b	=>  tmp = a; a + b; tmp
|> |> Similarly for other composite operators.
|> |>
|> |> a != b	=> !(a == b)	and vice versa
|> |> a >= b	=> !(a < b)	etc
|> |> a < b	=> a - b < 0	etc
|> |> a - b	=> a + (-b)	and vice versa
|> |> -b		=> 0 - b
|> |> +b		=> b
|> |> a++		=> a += 1	also --
|> |> a->b		=>  (*a).b
|>
|> The standard header <utility> (20.2.1) already defines template-
|> operators for the relational operators, deducing them to == and <
|> a != b		=> !(a == b)
|> a >  b		=>   b < a
|> a <= b		=> !(b < a)
|> a >= b		=> !(a < b)
|>
|> You can extend this idea:
|>
|> template<class T> T& operator+=(T&a, T&b) { return a = a + b; }
|> template<class T> T  operator- (T&a, T&b) { return a + (-b); }
|> template<class T> T  operator- (T&a)      { return 0 - a; }
|> template<class T> T& operator+ (T&a)      { return a; }
|> template<class T> T& operator++(T&a)      { return a += 1; }
|> template<class T> T& operator++(T&a,int)  { return ++a; }

This will not work: it prevent you from writing any templates
for these operators over types that do not have "1" or "0"
or that need a definition other than the one above.

--
John.

John J. Barton        jjb@watson.ibm.com            (914)784-6645
	<http://www.research.ibm.com/xw-SoftwareTechnology>
H1-C13 IBM Watson Research Center P.O. Box 704 Hawthorne NY 10598
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