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digitalmars.D.learn - out parameter with default value

reply "AsmMan" <jckj33 gmail.com> writes:
Why it does works:

void f(out int c)
{
    if(some_cond)
	c = 10;
}

but it doesn't?

void f(out int c = 1)
{
    if(some_cond)
	c = 10;
}

it give compiler error:

Error: constant 1 is not an lvalue
Sep 29 2014
next sibling parent reply "AsmMan" <jckj33 gmail.com> writes:
My question is why it doesn't works and if there's a workaround
Sep 29 2014
parent reply "Marc =?UTF-8?B?U2Now7x0eiI=?= <schuetzm gmx.net> writes:
On Monday, 29 September 2014 at 16:09:11 UTC, AsmMan wrote:

 My question is why it doesn't works and if there's a workaround


For the same reason `ref` wouldn't work in this place: It doesn't 
accept rvalues.

A workaround might be to create a global variable that is 
initialized to the value you want, and use this as the default 
value. But this probably isn't what you look for, because you're 
most likely going to overwrite it, so the next time the function 
gets called, it will have a different value.
Sep 29 2014
parent reply "AsmMan" <jckj33 gmail.com> writes:
I had just forget out and ref are same as pointers... thanks guys
Sep 29 2014
parent ketmar via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> writes:
On Mon, 29 Sep 2014 20:22:41 +0000
AsmMan via Digitalmars-d-learn <digitalmars-d-learn puremagic.com>
wrote:


 I had just forget out and ref are same as pointers... thanks guys


yeah, that syntactic sugar can be confusing sometimes. ;-)
Sep 29 2014
prev sibling parent ketmar via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> writes:
On Mon, 29 Sep 2014 16:07:49 +0000
AsmMan via Digitalmars-d-learn <digitalmars-d-learn puremagic.com>
wrote:


 but it doesn't?
=20
 void f(out int c =3D 1)


'cause `out int c` is actually `int* c`. you can't assign int(1) to
pointer.
Sep 29 2014