Re: Querying parameter passing semantics for `auto ref const` variables

2017-01-15 Thread Nordlöw via Digitalmars-d-learn 

On Sunday, 15 January 2017 at 17:41:36 UTC, Nordlöw wrote:

This

struct S { int x, y; }
void f()(auto ref const S s)
{
pragma(msg, "type:", typeof(s), " isRef:", isRef!s);
}
f(S.init);
S s;
f(s);

prints

type:const(S) isRef:false
type:const(S) isRef:true


given that

enum isRef(alias fn) = __traits(isRef, fn);

:)

Re: Querying parameter passing semantics for `auto ref const` variables

2017-01-15 Thread Nordlöw via Digitalmars-d-learn 

On Sunday, 15 January 2017 at 17:00:41 UTC, kinke wrote:

On Sunday, 15 January 2017 at 14:33:25 UTC, Nordlöw wrote:
A call to `isRef!T` inside the function `f` is always `false` 
for `l-value` and `r-value` passing.


According to 
https://dlang.org/spec/template.html#auto-ref-parameters, it 
should be `__traits(isRef, x)`.


This

struct S { int x, y; }
void f()(auto ref const S s)
{
pragma(msg, "type:", typeof(s), " isRef:", isRef!s);
}
f(S.init);
S s;
f(s);

prints

type:const(S) isRef:false
type:const(S) isRef:true

I made the mistake of incorrectly using

isRef!S

when I should have used

isRef!s

Thanks!

Re: Querying parameter passing semantics for `auto ref const` variables

2017-01-15 Thread kinke via Digitalmars-d-learn 

On Sunday, 15 January 2017 at 14:33:25 UTC, Nordlöw wrote:
A call to `isRef!T` inside the function `f` is always `false` 
for `l-value` and `r-value` passing.


According to 
https://dlang.org/spec/template.html#auto-ref-parameters, it 
should be `__traits(isRef, x)`.

Re: Querying parameter passing semantics for `auto ref const` variables

2017-01-15 Thread Nordlöw via Digitalmars-d-learn 

On Sunday, 15 January 2017 at 14:33:25 UTC, Nordlöw wrote:

Is there a way to query at compile-time whether a call to


Further, overloading such as

struct S { int x, y; }
static f(in S s) {}
static f(const ref S s) {}
f(S.init);
S s;
f(s);

fails as

declaration f is already defined

Querying parameter passing semantics for `auto ref const` variables

2017-01-15 Thread Nordlöw via Digitalmars-d-learn 

Is there a way to query at compile-time whether a call to

f(T)(auto ref const T x)

passed the variable `x` from a l-value or r-value?

A call to `isRef!T` inside the function `f` is always `false` for 
`l-value` and `r-value` passing.


I need this to detect automatic delayed evaluation of 
sub-expressions in my GNU MP wrapper at


https://github.com/nordlow/gmp-d