digitalmars.D.learn - identic ref/inout parameter

Wilhelm (20/20) Sep 14 2007 Who do I determine in a function (probably with a assert statement) that...

Regan Heath (9/34) Sep 14 2007 Maybe...

Regan Heath (5/42) Sep 14 2007 It's a pity that this doesn't work:
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Jarrett Billingsley (6/12) Sep 14 2007 Probably not _quite_ what you'd expect. "ref T[]" means "ref(T[])", not...

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Jarrett Billingsley (16/21) Sep 15 2007 Hm. It doesn't compile with the 'ref' for the foreach loop values, but ...

Wilhelm <Wilhelm.Kopenpart t-online.de> writes:

Who do I determine in a function (probably with a assert statement) that the
function with more the one ref/inout parameters of the same type are not called
with the same variable like:

private import std.stdio;

int main(char[][] args)
{
    int i=3;
    test( i,i,i,i);
    return 0;
}


void test(ref int r1, ref int r2, inout int i1, inout int i2)
{
	writefln ("           Ref: r1=%d r2=%d", r1, r2);
	writefln ("         InOut: i1=%d i2=%d", i1, i2);
	r1 += 2;
	writefln ("r1 += 2;   Ref: r1=%d r2=%d", r1, r2);
	writefln ("r1 += 2; InOut: i1=%d i2=%d", i1, i2);
	i2 += 2;
	writefln ("i1 += 2;   Ref: r1=%d r2=%d", r1, r2);
	writefln ("i1 += 2; InOut: i1=%d i2=%d", i1, i2);
}

!! That may cause interesting results !!

Sep 14 2007

Regan Heath <regan netmail.co.nz> writes:

Wilhelm wrote:
 Who do I determine in a function (probably with a assert statement) that the
function with more the one ref/inout parameters of the same type are not called
with the same variable like:
 
 private import std.stdio;
 
 int main(char[][] args)
 {
     int i=3;
     test( i,i,i,i);
     return 0;
 }
 
 
 void test(ref int r1, ref int r2, inout int i1, inout int i2)
 {
 	writefln ("           Ref: r1=%d r2=%d", r1, r2);
 	writefln ("         InOut: i1=%d i2=%d", i1, i2);
 	r1 += 2;
 	writefln ("r1 += 2;   Ref: r1=%d r2=%d", r1, r2);
 	writefln ("r1 += 2; InOut: i1=%d i2=%d", i1, i2);
 	i2 += 2;
 	writefln ("i1 += 2;   Ref: r1=%d r2=%d", r1, r2);
 	writefln ("i1 += 2; InOut: i1=%d i2=%d", i1, i2);
 }
 
 !! That may cause interesting results !!

Maybe...

	assert(&r1 != &r2);
	assert(&r1 != &i1);
	assert(&r1 != &i2);
	assert(&r2 != &i1);
	assert(&r2 != &i2);
	assert(&i1 != &i2);

Regan

Sep 14 2007

Regan Heath <regan netmail.co.nz> writes:

Regan Heath wrote:
 Wilhelm wrote:
 Who do I determine in a function (probably with a assert statement) 
 that the function with more the one ref/inout parameters of the same 
 type are not called with the same variable like:

 private import std.stdio;

 int main(char[][] args)
 {
     int i=3;
     test( i,i,i,i);
     return 0;
 }


 void test(ref int r1, ref int r2, inout int i1, inout int i2)
 {
     writefln ("           Ref: r1=%d r2=%d", r1, r2);
     writefln ("         InOut: i1=%d i2=%d", i1, i2);
     r1 += 2;
     writefln ("r1 += 2;   Ref: r1=%d r2=%d", r1, r2);
     writefln ("r1 += 2; InOut: i1=%d i2=%d", i1, i2);
     i2 += 2;
     writefln ("i1 += 2;   Ref: r1=%d r2=%d", r1, r2);
     writefln ("i1 += 2; InOut: i1=%d i2=%d", i1, i2);
 }

 !! That may cause interesting results !!

 
 Maybe...
 
     assert(&r1 != &r2);
     assert(&r1 != &i1);
     assert(&r1 != &i2);
     assert(&r2 != &i1);
     assert(&r2 != &i2);
     assert(&i1 != &i2);

It's a pity that this doesn't work:

assert(r1 is r2);
..etc..

Regan

Sep 14 2007

Downs <default_357-line yahoo.de> writes:

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Regan Heath wrote:
 Wilhelm wrote:
 Who do I determine in a function (probably with a assert statement)
 that the function with more the one ref/inout parameters of the same
 type are not called with the same variable like:

 private import std.stdio;

 int main(char[][] args)
 {
     int i=3;
     test( i,i,i,i);
     return 0;
 }


 void test(ref int r1, ref int r2, inout int i1, inout int i2)
 {
     writefln ("           Ref: r1=%d r2=%d", r1, r2);
     writefln ("         InOut: i1=%d i2=%d", i1, i2);
     r1 += 2;
     writefln ("r1 += 2;   Ref: r1=%d r2=%d", r1, r2);
     writefln ("r1 += 2; InOut: i1=%d i2=%d", i1, i2);
     i2 += 2;
     writefln ("i1 += 2;   Ref: r1=%d r2=%d", r1, r2);
     writefln ("i1 += 2; InOut: i1=%d i2=%d", i1, i2);
 }

 !! That may cause interesting results !!

 
 Maybe...
 
     assert(&r1 != &r2);
     assert(&r1 != &i1);
     assert(&r1 != &i2);
     assert(&r2 != &i1);
     assert(&r2 != &i2);
     assert(&i1 != &i2);
 
 Regan

To clean it up a little

void assertUnique(T)(ref T[] values...) {
  foreach (index, ref value; values[0..$-1])
    foreach (ref value2; values[index+1..$])
      assert(&value != &value2);
}

Untested, but should work.
 --downs
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Sep 14 2007

"Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:

"Downs" <default_357-line yahoo.de> wrote in message 
news:fce15c$1h7e$1 digitalmars.com...

 To clean it up a little

 void assertUnique(T)(ref T[] values...) {
  foreach (index, ref value; values[0..$-1])
    foreach (ref value2; values[index+1..$])
      assert(&value != &value2);
 }

Probably not _quite_ what you'd expect.  "ref T[]" means "ref(T[])", not 
"(ref T)[]".  That is, a reference to an array, not an array of references. 
So it'd have to be "T*[] values..." instead, and called as 
"assertUnique(&r1, &r2, &i1, &i2)".

Sep 14 2007

Downs <default_357-line yahoo.de> writes:

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Jarrett Billingsley wrote:
 "Downs" <default_357-line yahoo.de> wrote in message 
 news:fce15c$1h7e$1 digitalmars.com...
 
 To clean it up a little

 void assertUnique(T)(ref T[] values...) {
  foreach (index, ref value; values[0..$-1])
    foreach (ref value2; values[index+1..$])
      assert(&value != &value2);
 }

 
 Probably not _quite_ what you'd expect.  "ref T[]" means "ref(T[])", not 
 "(ref T)[]".  That is, a reference to an array, not an array of references. 
 So it'd have to be "T*[] values..." instead, and called as 
 "assertUnique(&r1, &r2, &i1, &i2)". 
 
 

Damn, you're right.
How about this?

void assertUnique(T...)(ref T tuple) {
  foreach (index, ref v1; tuple[0..$-1])
    foreach (ref v2; tuple[index+1..$])
      assert(&v1 != &v2);
}
 --downs
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Sep 14 2007

"Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:

"Downs" <default_357-line yahoo.de> wrote in message 
news:fcetv4$6ii$1 digitalmars.com...

 void assertUnique(T...)(ref T tuple) {
  foreach (index, ref v1; tuple[0..$-1])
    foreach (ref v2; tuple[index+1..$])
      assert(&v1 != &v2);
 }

Hm.  It doesn't compile with the 'ref' for the foreach loop values, but when 
you take those out, it doesn't work.  It works if you just index the tuple 
instead, though:

void assertUnique(T...)(ref T tuple)
{
    foreach(i1, v1; tuple[0 .. $ - 1])
        foreach(i2, v2; tuple[i1 + 1 .. $])
            assert(&tuple[i1] != &tuple[i1 + 1 + i2]);
}

Sadly, this can't be used in a function precondition because it gives the 
error "cannot modify parameter in precondition".  The compiler thinks you're 
trying to modify the parameters when you pass them to assertUnique.  (A case 
where "const ref" would be useful!  How about that.)  But you can still call 
it at the beginning of the function.

Sep 15 2007

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digitalmars.D.learn - identic ref/inout parameter