Another question about typedef...

I am using typedef long location ;

Now I would like to use tango.math.random.Random. But I am having problems with
calling r.uniformR( hi ) when r is a random genarator, and hi is of type location.
I need to call
r.uniform!(long)( cast(long)(hi) ) ;

This is ugly, and will work only as long as location remains long. If I decide to change location to 'int', I'll have to go and edit all of these casts.
Is there a better way to do this?
Is there a way to get the base type of location? Something like
typeof(hi), but that returns 'long' when location is long, and 'int' when int?

thanks!

MLT:
> Is there a way to get the base type of location?

See the BaseTypedef() template in the "templates" module of my dlibs (they are for Phobos):
http://www.fantascienza.net/leonardo/so/libs_d.zip

Bye,
bearophile

bearophile wrote:
> MLT:
>> Is there a way to get the base type of location?
> 
> See the BaseTypedef() template in the "templates" module of my dlibs (they are for Phobos):
> http://www.fantascienza.net/leonardo/so/libs_d.zip
> 
> Bye,
> bearophile

It's probably something along the lines of:

template BaseTypedef(T)
{
    static if( is( T U == typedef ) )
        alias U BaseTypedef;
    else
        alias T BaseTypedef;
}

  -- Daniel

Thank you very much!
I'm using tango, and have a problem combining both on OSX. But I just copied the definition:
template BaseTypedef(T) {
    static if( is( T BaseType1 == typedef ) )
        alias BaseTypedef!(BaseType1) BaseTypedef;
    else
        alias T BaseTypedef;
}

and it works! Great!!
Hmmm... but how?
in "is( T BaseType1 == typedef )" Basetype1 seems to be a variable of type T.
Then calling 'alias BaseTypedef!(BaseType1) BaseTypedef;' does not seem to strip away a layer... isn't it still called on a variable of type T? Or does 'is()' do some magic?


bearophile Wrote:

> MLT:
> > Is there a way to get the base type of location?
> 
> See the BaseTypedef() template in the "templates" module of my dlibs (they are for Phobos):
> http://www.fantascienza.net/leonardo/so/libs_d.zip
> 
> Bye,
> bearophile

On Fri, May 1, 2009 at 9:54 AM, MLT <none@anone.com> wrote:

> and it works! Great!!
> Hmmm... but how?
> in "is( T BaseType1 == typedef )" Basetype1 seems to be a variable of type T.
> Then calling 'alias BaseTypedef!(BaseType1) BaseTypedef;' does not seem to strip away a layer... isn't it still called on a variable of type T? Or does 'is()' do some magic?

is() does a lot of magic.  It has the worst, most confusing thing in
the language.

When you do is(T U == typedef), it will evaluate to true if T is a typedef, and if so, will declare an alias U which is aliased to the base type of the typedef.  It's not a variable, just a type.

The recursive call to BaseTypedef!(BaseType1) is there because BaseType1 _itself_ may be a typedef.  For instance:

typedef int a;
typedef a b;

If you call BaseTypedef!(b), the is() will figure out that its base
type is a; then it recursively calls BaseTypedef!(a), which determines
the base type is int; then it recursively calls BaseTypedef!(int),
where the is() evaluates to false, it hits the base case of recursion,
and evaluates to int.  That propagates up, and so BaseTypedef!(b)
evaluates to int.

MLT:
>But I just copied the definition:<

If you have to copy something, then must always copy the unittests too, they are a part of the code. They aren't there just for show.
And usually it's better to also copy the relative ddocs too, they are part of the user interface of a function/template/class/method/etc.

Bye,
bearophile