🚀 go-pugleaf

rp@iscp.bellcore.com (Robert Pearlman) writes:

>jjb@watson.ibm.com (John Barton) writes:
>|> schuenem@informatik.tu-muenchen.de (Ulf Schuenemann) writes:
>|> |> 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.

I don't think that is correct now that partial specialization is
allowed - if you need a different definition, can't you just define a
(template) specialization?

>The substitution for a+=b also won't work; if evaluation of a
>has a side effect the side effect will happen twice.  

That's definitely not correct.  Templates are not just macro substitution.
The arguments are only evaluated once.

--
Fergus Henderson             	WWW: http://www.cs.mu.oz.au/~fjh
fjh@cs.mu.oz.au              	PGP: finger fjh@128.250.37.3


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