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digitalmars.D.learn - question about ref keyword

reply Jack <jckj33 gmail.com> writes:
let's assume this class:

class C
{
	private S m_s;

	this()
	{
		m_s = S(30);
	}

	ref S value() { return m_s; }
	ref S value(ref S s)
	{
		return m_s = s;
	}
}

and I do something like this:

	auto s1 = S(40);
	auto c = new C();
         c.value = s1;
	s1.n = 80;


give that value has ref in its signature, the s1 is passed as a 
"pointer" right? also, when I do: m_s = s; m_s is a copy of s1 or 
a reference to it? setting s1.n to 80 in the next line doesn't 
seem to change c.value so it seems it passed s1 as a pointer but 
when it comes to assignment a copy was made?
Mar 18
parent ag0aep6g <anonymous example.com> writes:
On Thursday, 18 March 2021 at 16:59:24 UTC, Jack wrote:
 let's assume this class:

 class C
 {
 	private S m_s;

 	this()
 	{
 		m_s = S(30);
 	}

 	ref S value() { return m_s; }
 	ref S value(ref S s)
 	{
 		return m_s = s;
 	}
 }

 and I do something like this:

 	auto s1 = S(40);
 	auto c = new C();
         c.value = s1;
 	s1.n = 80;


 give that value has ref in its signature, the s1 is passed as a 
 "pointer" right?
right
 also, when I do: m_s = s; m_s is a copy of s1 or a reference to 
 it?
a copy
 setting s1.n to 80 in the next line doesn't seem to change 
 c.value so it seems it passed s1 as a pointer but when it comes 
 to assignment a copy was made?
You got it. If you want the pointer, you can get it taking the address of s: `S* p = &s;`.
Mar 18