digitalmars.D.learn - opIn

digitalmars.D.learn - opIn_r not detected

spir (30/30) Feb 10 2011 Hello,

Steven Schveighoffer (6/32) Feb 10 2011 There is a bug in the compiler that the message says associative array i...

spir (43/78) Feb 10 2011 http://d.puremagic.com/issues/show_bug.cgi?id=5558

Stewart Gordon (6/13) Feb 10 2011

spir (7/22) Feb 10 2011 Works, indeed, but using opEquals on s2, and because s2 is not "pointed"...

Stewart Gordon (13/19) Feb 12 2011 In what compiler version/platform?

spir <denis.spir gmail.com> writes:

Hello,

Implicite deref of struct pointers on member access works fine for data, 
methods, even special methods with language semantics like opEquals (see 
example below).
But I cannot have 'in' work with method opIn_r. I get:
     Error: rvalue of in expression must be an associative array, not S*
What do I have wrong? Or is it a bug: the compiler does not even search the 
struct for opIn_r? But then, why does it do it for opEquals?

Denis

struct S {
     int i;
     void show() { writeln(i); }
     const bool opEquals (ref const(S) s) {
         writeln("==");
         return (i == s.i);
     }
     bool opIn_r (int j) { return (i==j); }
}
unittest {
     S* sp = &(S(1));
     writeln(sp.i);
     sp.show();
     S s2 = S(1);
     writeln(sp == s2);
     writeln(1 in sp);
}

-- 
_________________
vita es estrany
spir.wikidot.com

Feb 10 2011

"Steven Schveighoffer" <schveiguy yahoo.com> writes:

On Thu, 10 Feb 2011 07:59:06 -0500, spir <denis.spir gmail.com> wrote:

 Hello,

 Implicite deref of struct pointers on member access works fine for data,  
 methods, even special methods with language semantics like opEquals (see  
 example below).
 But I cannot have 'in' work with method opIn_r. I get:
      Error: rvalue of in expression must be an associative array, not S*
 What do I have wrong? Or is it a bug: the compiler does not even search  
 the struct for opIn_r? But then, why does it do it for opEquals?

 Denis

 struct S {
      int i;
      void show() { writeln(i); }
      const bool opEquals (ref const(S) s) {
          writeln("==");
          return (i == s.i);
      }
      bool opIn_r (int j) { return (i==j); }
 }
 unittest {
      S* sp = &(S(1));
      writeln(sp.i);
      sp.show();
      S s2 = S(1);
      writeln(sp == s2);
      writeln(1 in sp);
 }

There is a bug in the compiler that the message says associative array is  
required.  There is a bugzilla issue somewhere on that...

But it does look like it should work, I'd file a separate bugzilla on the  
opIn_r not working.

-Steve

Feb 10 2011

spir <denis.spir gmail.com> writes:

On 02/10/2011 02:39 PM, Steven Schveighoffer wrote:
 On Thu, 10 Feb 2011 07:59:06 -0500, spir <denis.spir gmail.com> wrote:

 Hello,

 Implicite deref of struct pointers on member access works fine for data,
 methods, even special methods with language semantics like opEquals (see
 example below).
 But I cannot have 'in' work with method opIn_r. I get:
 Error: rvalue of in expression must be an associative array, not S*
 What do I have wrong? Or is it a bug: the compiler does not even search the
 struct for opIn_r? But then, why does it do it for opEquals?

 Denis

 struct S {
 int i;
 void show() { writeln(i); }
 const bool opEquals (ref const(S) s) {
 writeln("==");
 return (i == s.i);
 }
 bool opIn_r (int j) { return (i==j); }
 }
 unittest {
 S* sp = &(S(1));
 writeln(sp.i);
 sp.show();
 S s2 = S(1);
 writeln(sp == s2);
 writeln(1 in sp);
 }

 There is a bug in the compiler that the message says associative array is
 required. There is a bugzilla issue somewhere on that...

 But it does look like it should work, I'd file a separate bugzilla on the
 opIn_r not working.

http://d.puremagic.com/issues/show_bug.cgi?id=5558
Content reproduced below; tell me please if the description is (not) ok.

Denis

==========================================
Issue 5558 - opIn_r not detected as method for 'in' in pointed struct

In a struct, opIn_r is not detected by the compiler as beeing the method 
implementing the operator 'in'. Example:

struct S {
     int i;
     void show() { writeln(i); }
     const bool opEquals (ref const(S) s) {
         writeln("==");
         return (i == s.i);
     }
     bool opIn_r (int j) { return (i==j); }
}
unittest {
     S* sp = &(S(1));
     writeln(sp.i);
     sp.show();

     S s2 = S(1);
     writeln(sp == s2);
     writeln(1 in s2);

     // error:
     writeln(1 in sp);
}
==>
     Error: rvalue of in expression must be an associative array, not S*

This concerns opIn_r on pointed struct only; the other struct members of the 
structn and the not-pointed one are only here to contrast:
* Data members, regular methods and even "language methods" like opEquals are 
correctly taken into account on a struct, even via implicite deref.
* opIn_r is correctly detected as implementing 'in' on a non-pointed or 
explicitely dereferenced struct.

Thus, the code works fine if one comments out the very last line.

Waiting for a fix, the error message should be corrected to eg:
     Error: right operand of 'in' operation must be an associative array
            or implement the operator 'in' via method opIn_r

-- 
_________________
vita es estrany
spir.wikidot.com

Feb 10 2011

Stewart Gordon <smjg_1998 yahoo.com> writes:

On 10/02/2011 12:59, spir wrote:
 Hello,

 Implicite deref of struct pointers on member access works fine for data,
methods, even
 special methods with language semantics like opEquals (see example below).
 But I cannot have 'in' work with method opIn_r. I get:
 Error: rvalue of in expression must be an associative array, not S*
 What do I have wrong? Or is it a bug: the compiler does not even search the
struct for
 opIn_r? But then, why does it do it for opEquals?

<snip>

That got me thinking.  It would appear that it auto-dereferences only the left
operand. 
Try adding this to your code and see:

     writeln(s2 == sp);

Stewart.

Feb 10 2011

spir <denis.spir gmail.com> writes:

On 02/10/2011 07:43 PM, Stewart Gordon wrote:
 On 10/02/2011 12:59, spir wrote:
 Hello,

 Implicite deref of struct pointers on member access works fine for data,
 methods, even
 special methods with language semantics like opEquals (see example below).
 But I cannot have 'in' work with method opIn_r. I get:
 Error: rvalue of in expression must be an associative array, not S*
 What do I have wrong? Or is it a bug: the compiler does not even search the
 struct for
 opIn_r? But then, why does it do it for opEquals?

 <snip>

 That got me thinking. It would appear that it auto-dereferences only the left
 operand. Try adding this to your code and see:

 writeln(s2 == sp);

Works, indeed, but using opEquals on s2, and because s2 is not "pointed".

Denis
-- 
_________________
vita es estrany
spir.wikidot.com

Feb 10 2011

Stewart Gordon <smjg_1998 yahoo.com> writes:

On 10/02/2011 22:32, spir wrote:
 On 02/10/2011 07:43 PM, Stewart Gordon wrote:

<snip>
 That got me thinking. It would appear that it auto-dereferences only the left
 operand. Try adding this to your code and see:

 writeln(s2 == sp);

 Works, indeed, but using opEquals on s2, and because s2 is not "pointed".

In what compiler version/platform?

Here's what I get (DMD 2.051, Windows, after fixing the missing import):
----------
C:\Users\Stewart\Documents\Programming\D\Tests>dmd -unittest opin_r.d
opin_r.d(19): Error: function opin_r.S.opEquals (ref const(S) s) const is not ca
llable using argument types (S*)
opin_r.d(19): Error: cannot implicitly convert expression (sp) of type S* to con
st(S)
----------

Or maybe you forgot the -unittest?

Stewart.

Feb 12 2011

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digitalmars.D.learn - opIn_r not detected