• "Stefan" <dlanglearnthrowaway thisisnotmyrealemail.com> Aug 15 2012
• "RommelVR" <daniel350 bigpond.com> Aug 15 2012
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> Aug 15 2012
• "d_follower" <d_follower fakemail.com> Aug 15 2012
• "d_follower" <d_follower fakemail.com> Aug 15 2012
• "Jesse Phillips" <jessekphillips+D gmail.com> Aug 15 2012
• Andrej Mitrovic <andrej.mitrovich gmail.com> Aug 15 2012
• Justin Whear <justin economicmodeling.com> Aug 15 2012
• Leandro Motta Barros <lmb stackedboxes.org> Aug 15 2012

"Stefan" <dlanglearnthrowaway thisisnotmyrealemail.com> writes:

Hi there, I'm having trouble getting the following code to 
compile:

import std.stdio;

string a = "a";
string b = a;

void main()
{
     writeln(b);
}

DMD spits out the error "test.d(4): Error: variable a cannot be 
read at compile time". Is there any way to tell the compiler I 
want b evaluated at runtime, or am I missing something obvious 
here?

"RommelVR" <daniel350 bigpond.com> writes:

On Wednesday, 15 August 2012 at 13:36:26 UTC, Stefan wrote:
 Hi there, I'm having trouble getting the following code to 
 compile:

 import std.stdio;

 string a = "a";
 string b = a;

 void main()
 {
     writeln(b);
 }

 DMD spits out the error "test.d(4): Error: variable a cannot be 
 read at compile time". Is there any way to tell the compiler I 
 want b evaluated at runtime, or am I missing something obvious 
 here?


Make a an enum, const or otherwise immutable.

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 08/15/2012 06:55 AM, d_follower wrote:
 On Wednesday, 15 August 2012 at 13:41:10 UTC, RommelVR wrote:
 Make a an enum, const or otherwise immutable.


 I don't think you understood the question.


I thought RommelVR did understand the question. Try this:

import std.stdio;

enum a = "a";
string b = a;

void main()
{
     writeln(b);
}

Ali

-- 
D Programming Language Tutorial: http://ddili.org/ders/d.en/index.html

"d_follower" <d_follower fakemail.com> writes:

On Wednesday, 15 August 2012 at 13:41:10 UTC, RommelVR wrote:
 Make a an enum, const or otherwise immutable.


I don't think you understood the question.

"d_follower" <d_follower fakemail.com> writes:

On Wednesday, 15 August 2012 at 13:36:26 UTC, Stefan wrote:
 Hi there, I'm having trouble getting the following code to 
 compile:

 import std.stdio;

 string a = "a";
 string b = a;        // line 4

 void main()
 {
     writeln(b);       // line 8
 }

 DMD spits out the error "test.d(4): Error: variable a cannot be 
 read at compile time". Is there any way to tell the compiler I 
 want b evaluated at runtime, or am I missing something obvious 
 here?


You must understand that your problem lies in line 4, not in line 
8, i.e. the following doesn't work either:

string a = "a";
string b = a;

I don't really know why, but it seems that you can only 
initialize globals with constants.

What you could do is something like this (I guess):

enum value = "a";
string a = value;
string b = value;

void main()
{
     writeln(b);
     b = "b";
     writeln(b);
}

"Jesse Phillips" <jessekphillips+D gmail.com> writes:

On Wednesday, 15 August 2012 at 13:36:26 UTC, Stefan wrote:
 Hi there, I'm having trouble getting the following code to 
 compile:

 import std.stdio;

 string a = "a";
 string b = a;

 void main()
 {
     writeln(b);
 }

 DMD spits out the error "test.d(4): Error: variable a cannot be 
 read at compile time". Is there any way to tell the compiler I 
 want b evaluated at runtime, or am I missing something obvious 
 here?


untested

string a = "a";

static this() {
     string b = a;
}

be aware of the details:

http://dlang.org/module.html#staticorder

Andrej Mitrovic <andrej.mitrovich gmail.com> writes:

On 8/15/12, d_follower <d_follower fakemail.com> wrote:
 I don't really know why, but it seems that you can only
 initialize globals with constants.


That's what the static constructor is for:
http://dlang.org/class.html#StaticConstructor
http://dlang.org/class.html#SharedStaticConstructor

Justin Whear <justin economicmodeling.com> writes:

On Wed, 15 Aug 2012 15:36:24 +0200, Stefan wrote:

 Hi there, I'm having trouble getting the following code to compile:
 
 import std.stdio;
 
 string a = "a";
 string b = a;
 
 void main()
 {
      writeln(b);
 }
 
 DMD spits out the error "test.d(4): Error: variable a cannot be read at
 compile time". Is there any way to tell the compiler I want b evaluated
 at runtime, or am I missing something obvious here?


D is not as context-sensitive as what you may be used to. This is a 
feature to make the language more parseable and human-grokable. 
Basically, the result of a module-level assignment should not depend on 
what came before, so this example code is invalid:

string a = "a";
a = "b";
string b = a;

This would require the declaration of b to depend on the order of the 
declarations/statements which come before it.  When you add in the import 
of modules, things would get really hairy really fast. So module-level 
declarations must use constant expressions (literals or symbols to 
constant data) in their initialization.

Justin

Leandro Motta Barros <lmb stackedboxes.org> writes:

Another option is to use "module constructors", as shown below. (But
somehow this all looks a bit fishy for me...)

LMB

----

import std.stdio;

string a = "a";
string b;

static this()
{
   b = a;
}

void main()
{
   writeln(b);
}


On Wed, Aug 15, 2012 at 11:03 AM, d_follower <d_follower fakemail.com> wrote:
 On Wednesday, 15 August 2012 at 13:36:26 UTC, Stefan wrote:
 Hi there, I'm having trouble getting the following code to compile:

 import std.stdio;

 string a = "a";
 string b = a;        // line 4

 void main()
 {
     writeln(b);       // line 8

 }

 DMD spits out the error "test.d(4): Error: variable a cannot be read at
 compile time". Is there any way to tell the compiler I want b evaluated at
 runtime, or am I missing something obvious here?



 You must understand that your problem lies in line 4, not in line 8, i.e.
 the following doesn't work either:


 string a = "a";
 string b = a;

 I don't really know why, but it seems that you can only initialize globals
 with constants.

 What you could do is something like this (I guess):

 enum value = "a";
 string a = value;
 string b = value;

 void main()
 {
     writeln(b);
     b = "b";
     writeln(b);
 }