• torhu (23/23) Jul 13 2007 Reposting from D.learn, since there were no answers there.
• Regan Heath (5/35) Jul 13 2007 I can't think of anything.
• torhu (21/57) Jul 13 2007 The are several simple workarounds. I guess my real question is if this...
• Stewart Gordon (7/41) Jul 13 2007 There's D_Version2.
• torhu (2/28) Jul 14 2007 Filed as bug #1342.

torhu <fake address.dude> writes:

Reposting from D.learn, since there were no answers there.

---
struct Inner
{
     int value;
}

struct Outer {
     //const(Inner) i;  // this fixes it, but is not valid in D 1.0
     Inner i;
}

const Inner ic = { 5 };  // const or invariant here makes no difference

Outer outer = {
     i: ic      // line 14
     //i: { 5 }  // this is allowed
};
---
c:\prog\test\D>dmd -c test
test.d(14): Error: non-constant expression cast(Inner)ic
---

Since the value of ic is fixed at compile time, shouldn't it be 
equivalent to a literal?

I'm trying to make this code work in D version 1 too, and since it's for 
an example, I'm trying to avoid any string mixins or other ugly workarounds.

Regan Heath <regan netmail.co.nz> writes:

torhu wrote:
 Reposting from D.learn, since there were no answers there.
 
 ---
 struct Inner
 {
     int value;
 }
 
 struct Outer {
     //const(Inner) i;  // this fixes it, but is not valid in D 1.0
     Inner i;
 }
 
 const Inner ic = { 5 };  // const or invariant here makes no difference
 
 Outer outer = {
     i: ic      // line 14
     //i: { 5 }  // this is allowed
 };
 ---
 c:\prog\test\D>dmd -c test
 test.d(14): Error: non-constant expression cast(Inner)ic
 ---
 
 Since the value of ic is fixed at compile time, shouldn't it be 
 equivalent to a literal?
 
 I'm trying to make this code work in D version 1 too, and since it's for 
 an example, I'm trying to avoid any string mixins or other ugly 
 workarounds.

I can't think of anything.

Is there a pre-defined version specifier for D1.0 and D2.0 you could use 
to conditionally select code which works for each?

Regan

torhu <fake address.dude> writes:

Regan Heath wrote:
 torhu wrote:
 Reposting from D.learn, since there were no answers there.
 
 ---
 struct Inner
 {
     int value;
 }
 
 struct Outer {
     //const(Inner) i;  // this fixes it, but is not valid in D 1.0
     Inner i;
 }
 
 const Inner ic = { 5 };  // const or invariant here makes no difference
 
 Outer outer = {
     i: ic      // line 14
     //i: { 5 }  // this is allowed
 };
 ---
 c:\prog\test\D>dmd -c test
 test.d(14): Error: non-constant expression cast(Inner)ic
 ---
 
 Since the value of ic is fixed at compile time, shouldn't it be 
 equivalent to a literal?
 
 I'm trying to make this code work in D version 1 too, and since it's for 
 an example, I'm trying to avoid any string mixins or other ugly 
 workarounds.

 
 I can't think of anything.
 
 Is there a pre-defined version specifier for D1.0 and D2.0 you could use 
 to conditionally select code which works for each?

The are several simple workarounds.  I guess my real question is if this 
not working is a bug or not. Shouldn't a struct value that's const or 
invariant be equal to a literal?   The value of 'ic' is known at 
compile-time.  Isn't that enough?

And can anyone explain this?

If I replace this
---
struct Outer {
     Inner i;
}
---

with this
---
struct Outer {
     const(Inner) i;
}
---

then i'm actually allowed to initialize outer's i with the const ic 
variable.  That seems a bit backwards, since I've actually changed i 
from non-const to const.

"Stewart Gordon" <smjg_1998 yahoo.com> writes:

"Regan Heath" <regan netmail.co.nz> wrote in message 
news:f77ov6$1hem$1 digitalmars.com...
 torhu wrote:
 Reposting from D.learn, since there were no answers there.

 ---
 struct Inner
 {
     int value;
 }

 struct Outer {
     //const(Inner) i;  // this fixes it, but is not valid in D 1.0
     Inner i;
 }

 const Inner ic = { 5 };  // const or invariant here makes no difference

 Outer outer = {
     i: ic      // line 14
     //i: { 5 }  // this is allowed
 };
 ---
 c:\prog\test\D>dmd -c test
 test.d(14): Error: non-constant expression cast(Inner)ic
 ---

 Since the value of ic is fixed at compile time, shouldn't it be 
 equivalent to a literal?

 I'm trying to make this code work in D version 1 too, and since it's for 
 an example, I'm trying to avoid any string mixins or other ugly 
 workarounds.

 I can't think of anything.

 Is there a pre-defined version specifier for D1.0 and D2.0 you could use 
 to conditionally select code which works for each?

There's D_Version2.

But there's still a problem - code that is CC'd out still has to be 
syntactically valid.  You'd have to put the code that relies on 2.0 syntax 
in a separate, conditionally imported module.

Stewart. 

torhu <no spam.invalid> writes:

torhu wrote:
 Reposting from D.learn, since there were no answers there.
 
 ---
 struct Inner
 {
      int value;
 }
 
 struct Outer {
      //const(Inner) i;  // this fixes it, but is not valid in D 1.0
      Inner i;
 }
 
 const Inner ic = { 5 };  // const or invariant here makes no difference
 
 Outer outer = {
      i: ic      // line 14
      //i: { 5 }  // this is allowed
 };
 ---
 c:\prog\test\D>dmd -c test
 test.d(14): Error: non-constant expression cast(Inner)ic
 ---
 
 Since the value of ic is fixed at compile time, shouldn't it be 
 equivalent to a literal?