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digitalmars.D.learn - static class instances not allowed?

reply "Eric" <eric makechip.com> writes:
The following code does not compile:

class Foo { int x; }
class Bar { static Foo f = new Foo(); }  // compiler error
static Foo g = new Foo(); // compiler error
void main() {}

(dmd7) desk3:~/tp/d_test2/dlib>dmd T.d
T.d(4): Error: variable T.Bar.f is mutable. Only const or 
immutable class thread local variable are allowed, not T.Foo
T.d(5): Error: variable T.g is mutable. Only const or immutable 
class thread local variable are allowed, not T.Foo

Why aren't static class instances allowed?  Is there a 
work-around,
or alternative approach to this?

Thanks,

Eric
Jun 11 2013
next sibling parent reply "bearophile" <bearophileHUGS lycos.com> writes:
Eric:

 The following code does not compile:

 class Foo { int x; }
 class Bar { static Foo f = new Foo(); }  // compiler error
 static Foo g = new Foo(); // compiler error
 void main() {}

 (dmd7) desk3:~/tp/d_test2/dlib>dmd T.d
 T.d(4): Error: variable T.Bar.f is mutable. Only const or 
 immutable class thread local variable are allowed, not T.Foo
 T.d(5): Error: variable T.g is mutable. Only const or immutable 
 class thread local variable are allowed, not T.Foo

 Why aren't static class instances allowed?  Is there a 
 work-around,
 or alternative approach to this?
C# compilers present bugs with a standard number, like: myprog.cs(7,60): error CS1525: ....... This is useful because you can then write an explanation page for each of those bugs, like CS1525: http://msdn.microsoft.com/en-gb/library/3hdyz4dw%28v=vs.80%29.aspx In such pages you can explain why Only const or immutable class thread local variable are allowed. Bye, bearophile
Jun 11 2013
next sibling parent "Eric" <eric makechip.com> writes:
 Why aren't static class instances allowed?  Is there a 
 work-around,
 or alternative approach to this?
C# compilers present bugs with a standard number, like: myprog.cs(7,60): error CS1525: ....... This is useful because you can then write an explanation page for each of those bugs, like CS1525: http://msdn.microsoft.com/en-gb/library/3hdyz4dw%28v=vs.80%29.aspx In such pages you can explain why Only const or immutable class thread local variable are allowed. Bye, bearophile
I'm not sure what you are saying. Are you implying that not allowing static class instances is a compiler bug? -Eric
Jun 11 2013
prev sibling parent "bearophile" <bearophileHUGS lycos.com> writes:
 C# compilers present bugs with a standard number, like:

 myprog.cs(7,60): error CS1525: .......

 This is useful because you can then write an explanation page 
 for each of those bugs, like CS1525:

 http://msdn.microsoft.com/en-gb/library/3hdyz4dw%28v=vs.80%29.aspx

 In such pages you can explain why Only const or immutable class 
 thread local variable are allowed.
The gentle Simen Kjaeraas has just created an enhancement request: http://d.puremagic.com/issues/show_bug.cgi?id=10335 Bye, bearophile
Jun 11 2013
prev sibling parent reply "Steven Schveighoffer" <schveiguy yahoo.com> writes:
On Tue, 11 Jun 2013 10:04:21 -0400, Eric <eric makechip.com> wrote:

 The following code does not compile:

 class Foo { int x; }
 class Bar { static Foo f = new Foo(); }  // compiler error
 static Foo g = new Foo(); // compiler error
These can be solved with a static ctor. Essentially, any static initializers must be evaluatable at compile-time. I know that in the most recent compiler classes have entered this realm, but I don't know the conditions on when they can be used. The accepted way: class Bar { static Foo f; static this() { f = new Foo(); } } static Foo g; static this() { g = new Foo(); } -Steve
Jun 11 2013
parent "Eric" <eric makechip.com> writes:
On Tuesday, 11 June 2013 at 16:09:39 UTC, Steven Schveighoffer 
wrote:
 On Tue, 11 Jun 2013 10:04:21 -0400, Eric <eric makechip.com> 
 wrote:

 The following code does not compile:

 class Foo { int x; }
 class Bar { static Foo f = new Foo(); }  // compiler error
 static Foo g = new Foo(); // compiler error
These can be solved with a static ctor. Essentially, any static initializers must be evaluatable at compile-time. I know that in the most recent compiler classes have entered this realm, but I don't know the conditions on when they can be used. The accepted way: class Bar { static Foo f; static this() { f = new Foo(); } } static Foo g; static this() { g = new Foo(); }
Great. This solved my problem. Many thanks. -Eric
 -Steve
Jun 11 2013