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D - template example question

reply Sean Kelly <sean ffwd.cx> writes:
This is in the template docs:


template factorial(int n : 1)
{
     enum { factorial = 1 }
}

template factorial(int n)
{
     // Note . used to find global template rather than enum
     enum { factorial = n* .factorial!(n-1) }
}

void test()
{
     printf("%d\n", factorial!(4)); // prints 24
}


Now it seems like a few things are going on here, but I can't find 
documentation on any of them.  First, using the . prefix seems 
equivalent to the :: prefix in C++, is this true?  Second, it seems that 
it's not an error to declare an enum with the same name as an enclosing 
template, but rather that the template can be considered equivalent to 
the underlying value.  Are there any other instances where this works?


Sean
Feb 12 2004
parent reply Hauke Duden <H.NS.Duden gmx.net> writes:
Sean Kelly wrote:
 Second, it seems that 
 it's not an error to declare an enum with the same name as an enclosing 
 template, but rather that the template can be considered equivalent to 
 the underlying value.  Are there any other instances where this works?

I believe it also works with (at least) classes and structs. Hauke
Feb 12 2004
parent reply "davepermen" <davepermen hotmail.com> writes:
and functions, too..

template max(T) { T max(T a,T b) { return a > b ? a : b; } }

max!(int)(5,10) returns 10 (with typeof(10) == int, of course:D)

"Hauke Duden" <H.NS.Duden gmx.net> schrieb im Newsbeitrag
news:c0h1vm$2ej0$1 digitaldaemon.com...
 Sean Kelly wrote:
 Second, it seems that
 it's not an error to declare an enum with the same name as an enclosing
 template, but rather that the template can be considered equivalent to
 the underlying value.  Are there any other instances where this works?

I believe it also works with (at least) classes and structs. Hauke

Feb 13 2004
parent Sam McCall <tunah.d tunah.net> writes:
davepermen wrote:
 and functions, too..
 
 template max(T) { T max(T a,T b) { return a > b ? a : b; } }
 
 max!(int)(5,10) returns 10 (with typeof(10) == int, of course:D)
 

shortcut templated functions with the restrictions: deduction doesn't work if the template is overloaded with the same number of parameters: void foo(T,int X)(T t) and void foo(T,double X)(T t) would have no type deduction, void foo(T,int[] X)(T t) and void foo(T,int X,int Y)(T t) are ok. For the matching template declaration (by number of args), each type variable must be the type of at least one parameter: void foo(T,U)(T[] t,U u) has no type deduction void foo(T,U)(T a,T[] b,int c,U d) is ok And it could be called with the normal function call syntax, max(5,10). Sam
Feb 13 2004