• tirithen (17/17) Jun 07 2020 How can I initialize my two dimensional array?
• Basile B. (39/57) Jun 08 2020 What you declare here is not a two dim array it's an associative

tirithen <tirithen gmail.com> writes:

How can I initialize my two dimensional array?

When I try to run the code below I get the error:

     Error: non-constant expression ["user":[cast(Capability)0], 
"administrator":[cast(Capability)1]]

Code:

     enum Capability {
       self,
       administer
     }

     alias Capabilities = immutable Capability[];

     private Capabilities[string] roleCapabilities = [
       "user" : [Capability.self], "administrator" : 
[Capability.administer]
     ];

I have tried adding more const and immutable prefixes but it 
still gives me the same error. The goal is that roleCapabilities 
should be an immutable/const two dimensional array.

Basile B. <b2.temp gmx.com> writes:

On Monday, 8 June 2020 at 06:37:18 UTC, tirithen wrote:
 How can I initialize my two dimensional array?

 When I try to run the code below I get the error:

     Error: non-constant expression ["user":[cast(Capability)0], 
 "administrator":[cast(Capability)1]]

 Code:

     enum Capability {
       self,
       administer
     }

     alias Capabilities = immutable Capability[];

     private Capabilities[string] roleCapabilities = [
       "user" : [Capability.self], "administrator" : 
 [Capability.administer]
     ];

 I have tried adding more const and immutable prefixes but it 
 still gives me the same error. The goal is that 
 roleCapabilities should be an immutable/const two dimensional 
 array.

What you declare here is not a two dim array it's an associative 
array.
Associative array implementation have limitations. To initialize 
one that doesn't have const expr as key you can use a static 
module constructor:

---
enum Capability {
   self,
   administer
}

alias Capabilities = immutable Capability[];

private Capabilities[string] roleCapabilities;

static this()
{
     roleCapabilities = [
       "user" : [Capability.self], "administrator" : 
[Capability.administer]
     ];
}
---

which is done at runtime, just before the D main() get executed.

Notes:

1. You can also use a function containing a switch statement 
instead of an assoc array.
2. the other way would work because it would be a static array, 
the enum member giving an integer index:

---
enum Capability {
   self,
   administer
}

alias Capabilities = immutable Capability[];

private string[Capability.max + 1] roleCapabilities = [
     Capability.self : "user",
     Capability.administer : "administrator",
];
---

but I suppose that is different.