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class MyClass(T) : Base if (ConstraintExpression) {} compilation error
May 24, 2013
ref2401
May 24, 2013
Simen Kjaeraas
May 24, 2013
Maxim Fomin
May 24, 2013
Gravatar of ref2401Posted by ref2401Reply
ref2401
Gravatar of ref2401


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Version D 2.062

Please explain what is causing the error

class Base
{ }

class Class(T) : Base
if (is(T == int))
{ }

Error: unrecognized declaration
Error: members expected
Error: Declaration expected, not 'if'
Error: { } expected following aggregate declaration
May 24, 2013
Gravatar of Simen KjaeraasPosted by Simen Kjaeraas
in reply to ref2401		Reply
Simen Kjaeraas
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Posted in reply to ref2401


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On 2013-05-24, 16:49, ref2401 wrote:

> Version D 2.062
>
> Please explain what is causing the error
>
> class Base
> { }
>
> class Class(T) : Base
> if (is(T == int))
> { }
>
> Error: unrecognized declaration
> Error: members expected
> Error: Declaration expected, not 'if'
> Error: { } expected following aggregate declaration

I'm confused too. This works:

class Base
{ }

class Class(T)
if (is(T == int)) : Base
{ }

void foo() {
   Base a = new Class!int;
}

-- 
Simen
May 24, 2013
Gravatar of Maxim FominPosted by Maxim Fomin
in reply to ref2401		Reply
Maxim Fomin
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Posted in reply to ref2401


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On Friday, 24 May 2013 at 14:49:24 UTC, ref2401 wrote:
> Version D 2.062
>
> Please explain what is causing the error
>
> class Base
> { }
>
> class Class(T) : Base
> if (is(T == int))
> { }
>
> Error: unrecognized declaration
> Error: members expected
> Error: Declaration expected, not 'if'
> Error: { } expected following aggregate declaration

because dmd acts as grammar nazi:

ClassTemplateDeclaration: class Identifier ( TemplateParameterList ) Constraintopt BaseClassListopt ClassBody