• ref2401 (17/17) Apr 24 2015 What advantages do ref params give over pointer params?
• bearophile (5/10) Apr 24 2015 ref params don't need the "*" every time you use them inside the
• ref2401 (3/3) Apr 24 2015 processPointer(&ms);
• bearophile (6/10) Apr 24 2015 C# avoids that problem requiring (in most cases) the usage of
• Steven Schveighoffer (7/24) Apr 24 2015 A ref param is somewhat safer, because you cannot do pointer arithmetic
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (7/8) Apr 24 2015 Another difference is that a ref parameter is not null and what is
• ref2401 (1/1) Apr 24 2015 Thank you

"ref2401" <refactor24 gmail.com> writes:

What advantages do ref params give over pointer params?

struct MyStruct {
	string str;

	this(string str) { this.str = str; }
}

void processRef(ref MyStruct ms) {
	writeln("processRef: ", ms);
}

void processPointer(MyStruct* ms) {
	writeln("processPointer: ", *ms);
}

void main(string[] args) {
	auto ms = MyStruct("the ultimate answer to everythin is the 
number 42");

	processRef(ms);
	processPointer(&ms);
}

"bearophile" <bearophileHUGS yahoo.com> writes:

ref2401:

 void processRef(ref MyStruct ms) {
 	writeln("processRef: ", ms);
 }

 void processPointer(MyStruct* ms) {
 	writeln("processPointer: ", *ms);

ref params don't need the "*" every time you use them inside the 
function, and don't need the "&" when you call the function.

Bye,
bearophile

"ref2401" <refactor24 gmail.com> writes:

processPointer(&ms);
I think doing this way is more descriptive.
Now all readers know that ms might be changed inside the function.

"bearophile" <bearophileHUGS yahoo.com> writes:

On Friday, 24 April 2015 at 13:39:35 UTC, ref2401 wrote:
 processPointer(&ms);
 I think doing this way is more descriptive.
 Now all readers know that ms might be changed inside the 
 function.


"ref" at the calling point too. But this idea was refused for D 
(also because it goes against UFCS chains).

Bye,
bearophile

Steven Schveighoffer <schveiguy yahoo.com> writes:

On 4/24/15 9:23 AM, ref2401 wrote:
 What advantages do ref params give over pointer params?

 struct MyStruct {
      string str;

      this(string str) { this.str = str; }
 }

 void processRef(ref MyStruct ms) {
      writeln("processRef: ", ms);
 }

 void processPointer(MyStruct* ms) {
      writeln("processPointer: ", *ms);
 }

 void main(string[] args) {
      auto ms = MyStruct("the ultimate answer to everythin is the number
 42");

      processRef(ms);
      processPointer(&ms);
 }

A ref param is somewhat safer, because you cannot do pointer arithmetic 
on it. A ref will ALWAYS point at the same memory location, because it 
cannot be rebound.

The compiler can also take advantage of the characteristics of ref, as 
it does with the -dip25 switch.

-Steve

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 04/24/2015 06:23 AM, ref2401 wrote:

 What advantages do ref params give over pointer params?

Another difference is that a ref parameter is not null and what is 
referred to is not an rvalue.

However, it is possible to break that expectation if a pointer is 
dereferenced and passed to a ref-taking function but then the actual 
object is gone before the reference is used.

Ali

"ref2401" <refactor24 gmail.com> writes:

Thank you