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digitalmars.D.learn - opIn_r not detected

reply 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
next sibling parent "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
prev sibling next sibling parent 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
prev sibling next sibling parent reply 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?

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
parent 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:

 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
prev sibling parent 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?

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