• Ruby The Roobster (4/4) Sep 28 2020 I thought alias could work like this with classes:
• =?UTF-8?Q?Ali_=c3=87ehreli?= (25/31) Sep 28 2020 That would work with template parameters:
• Paul Backus (20/24) Sep 28 2020 `alias` lets you create a new name for an entity that already

Ruby The Roobster <michaeleverestc79 gmail.com> writes:

I thought alias could work like this with classes:

alias test = MyClass(3,"H",9.1); //Assume the constructor 
parameters for MyClass are (int,string,double).

Can anybody fix this code?

=?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:

On 9/28/20 6:46 PM, Ruby The Roobster wrote:
 I thought alias could work like this with classes:

That would work with template parameters:

alias A = Foo!(3, "hello");

 
 alias test = MyClass(3,"H",9.1); //Assume the constructor parameters for 
 MyClass are (int,string,double).
 
 Can anybody fix this code?

You have to write a function (or a lambda):

class MyClass {
   this(int, string, double) {
   }
}

auto test1() {
   return new MyClass(3,"H",9.1);
}

auto test2 = () => new MyClass(4, "I", 10.1);

void main() {
   test1();
   test2();
}

However, I assumed each invocation would create a new object. If not, 
something like this:

MyClass test3;
static this() {
   test3 = new MyClass(5, "J", 11.1);
}

test3 is a single instance for each thread. A single instance for the 
whole program would be a different exercise. :)

Ali

Paul Backus <snarwin gmail.com> writes:

On Tuesday, 29 September 2020 at 01:46:56 UTC, Ruby The Roobster 
wrote:
 I thought alias could work like this with classes:

 alias test = MyClass(3,"H",9.1); //Assume the constructor 
 parameters for MyClass are (int,string,double).

 Can anybody fix this code?

`alias` lets you create a new name for an entity that already 
exists somewhere in your program.

The "entity" in question can be a lot of different things--a 
type, a variable, a function, a module, a template--but it must 
be something that exists independently of the alias. In other 
words, you cannot use `alias` to give a name to something that 
does not already have one.

But wait, you might ask, if that's true, how can you alias a 
lambda? It's an anonymous function; by definition, it doesn't 
have a name!

     alias increment = (int x) => x + 1;

The thing is...lambdas actually do have names. They're just 
generated internally by the compiler. You can't actually *use* 
them in your code, but they do occasionally show up in error 
messages:

     increment("hello");
     // Error: function literal `__lambda1(int x)` is not callable 
using argument types `(string)`