• Luc J. Bourhis (32/32) Jan 15 2015 Consider the following program:
• Daniel =?UTF-8?B?S296w6Fr?= via Digitalmars-d (27/69) Jan 15 2015 V Thu, 15 Jan 2015 12:31:00 +0000
• Luc J. Bourhis (4/7) Jan 15 2015 Thanks for this fix. But could you explain to me why there is a

"Luc J. Bourhis" <nemo nowhere.com> writes:

Consider the following program:

struct Expr(E) {
   const E expr;

   // If I replace the return type with "auto", dmd enters into an 
infinite loop instead of failing (see below)
    property Expr!(Transposed!E)  trans() {
     alias R = Transposed!E;
     return Expr!R(R(expr));
   }
}

struct Transposed(E) {
     const E expr;
}

struct Matrix {
    property auto asExpression() {
     return Expr!(Matrix)(this);
   }

   alias asExpression this;
}

void main() {
     auto a = Matrix();
     auto e = a.trans;
     pragma(msg, typeof(e).stringof);
}

It fails to compile:

~> dmd -v | head -n1
DMD64 D Compiler v2.066-devel
~> dmd -c expression_template.d
expression_template.d(4): Error: template instance 
expression_template.Transposed!(Transposed!(Transposed!(Transposed!( 
.................. ) recursive expansion

Am I missing something?

Daniel =?UTF-8?B?S296w6Fr?= via Digitalmars-d writes:

V Thu, 15 Jan 2015 12:31:00 +0000
"Luc J. Bourhis via Digitalmars-d" <digitalmars-d puremagic.com>
napsáno:

 Consider the following program:
 
 struct Expr(E) {
    const E expr;
 
    // If I replace the return type with "auto", dmd enters into an 
 infinite loop instead of failing (see below)
     property Expr!(Transposed!E)  trans() {
      alias R = Transposed!E;
      return Expr!R(R(expr));
    }
 }
 
 struct Transposed(E) {
      const E expr;
 }
 
 struct Matrix {
     property auto asExpression() {
      return Expr!(Matrix)(this);
    }
 
    alias asExpression this;
 }
 
 void main() {
      auto a = Matrix();
      auto e = a.trans;
      pragma(msg, typeof(e).stringof);
 }
 
 It fails to compile:
 
 ~> dmd -v | head -n1
 DMD64 D Compiler v2.066-devel
 ~> dmd -c expression_template.d
 expression_template.d(4): Error: template instance 
 expression_template.Transposed!(Transposed!(Transposed!(Transposed!( 
 .................. ) recursive expansion
 
 Am I missing something?
 



This is ok, there is really recursive expansion here, I guess you want
something like this?

struct Expr(E) {
    const E expr;

     property auto trans() {
        alias R = Transposed!E;
        return R(expr);
    }
}

struct Transposed(E) {
    const E expr;
}

struct Matrix {
     property auto asExpression() {
        return Expr!(Matrix)(this);
    }
    
    alias asExpression this;
}

void main() {
    auto a = Matrix();
    auto e = a.trans;
    pragma(msg, typeof(e).stringof);
}

"Luc J. Bourhis" <nemo nowhere.com> writes:

On Thursday, 15 January 2015 at 13:14:41 UTC, Daniel Kozák via 
Digitalmars-d wrote:
 This is ok, there is really recursive expansion here, I guess 
 you want something like this?

 [...]

Thanks for this fix. But could you explain to me why there is a 
recursive expansion?