• Tom Browder via Digitalmars-d-learn (10/10) Jun 12 2014 This will not compile:
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (4/11) Jun 12 2014 alias works only with types. Being an expression (not an object), null
• Andrew Edwards (4/19) Jun 12 2014 void foo() {}
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (10/13) Jun 12 2014 Seems to be an old behavior. That does not compile with 2.066:
• Adam D. Ruppe (3/3) Jun 12 2014 since null is a value maybe you want
• Tom Browder via Digitalmars-d-learn (5/8) Jun 12 2014 That works.
• monarch_dodra (26/29) Jun 12 2014 I *think* the issue might be that "null" is an rvalue? Because

Tom Browder via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> writes:

This will not compile:

  alias blah = null;

The dmd message are:

di/test_hdr.d(10): Error: basic type expected, not null
di/test_hdr.d(10): Error: semicolon expected to close alias declaration
di/test_hdr.d(10): Error: Declaration expected, not 'null'

Are there any other objects that cannot be aliased?

Thanks,

Best,

-Tom

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

On 06/12/2014 01:26 PM, Tom Browder via Digitalmars-d-learn wrote:

 This will not compile:

    alias blah = null;

 The dmd message are:

 di/test_hdr.d(10): Error: basic type expected, not null
 di/test_hdr.d(10): Error: semicolon expected to close alias declaration
 di/test_hdr.d(10): Error: Declaration expected, not 'null'

 Are there any other objects that cannot be aliased?

alias works only with types. Being an expression (not an object), null 
cannot not work with alias.

Ali

Andrew Edwards <ridimz yahoo.com> writes:

On 6/12/14, 4:29 PM, Ali Çehreli wrote:
 On 06/12/2014 01:26 PM, Tom Browder via Digitalmars-d-learn wrote:

  > This will not compile:
  >
  >    alias blah = null;
  >
  > The dmd message are:
  >
  > di/test_hdr.d(10): Error: basic type expected, not null
  > di/test_hdr.d(10): Error: semicolon expected to close alias declaration
  > di/test_hdr.d(10): Error: Declaration expected, not 'null'
  >
  > Are there any other objects that cannot be aliased?

 alias works only with types. Being an expression (not an object), null
 cannot not work with alias.

 Ali

void foo() {}
alias bar = foo();

Am I just misunderstanding what is meant by types?

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

On 06/12/2014 01:36 PM, Andrew Edwards wrote:

 void foo() {}
 alias bar = foo();

 Am I just misunderstanding what is meant by types?

Seems to be an old behavior. That does not compile with 2.066:

Error: function declaration without return type. (Note that constructors 
are always named 'this')

The following compiles though:

alias bar = foo;

I stand corrected: alias works not only with types but with symbols as 
well. I was right about the original code though: "Aliases cannot be 
used for expressions".

Ali

"Adam D. Ruppe" <destructionator gmail.com> writes:

since null is a value maybe you want

enum blah = null;

you may also give it a type after the enum word

Tom Browder via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> writes:

On Thu, Jun 12, 2014 at 4:58 PM, Adam D. Ruppe via Digitalmars-d-learn
<digitalmars-d-learn puremagic.com> wrote:
 since null is a value maybe you want

 enum blah = null;

That works.

 you may also give it a type after the enum word

But I can't get any other variant to work so far.

-Tom

"monarch_dodra" <monarchdodra gmail.com> writes:

On Thursday, 12 June 2014 at 21:58:32 UTC, Adam D. Ruppe wrote:
 since null is a value maybe you want

 enum blah = null;

 you may also give it a type after the enum word

I *think* the issue might be that "null" is an rvalue? Because 
you can alias variable names all you want. I do it all the time 
for templates where I *may* need a temporary.

eg:

void foo(T)(T val)
{
     static if (isUnsigned!T)
         alias uval = val;
     else
         auto uval = unsigned(val);
     ...
}

It's also quite useful with varargs:
alias a0 = args[0];

Also, you can't alias things like "int.init" either. I'm not sure 
the "rvalue" thing is the source, because these work:

//----struct S
{
     static int i;
     static int j()  property;
}
alias a = S.i;
alias b = S.j;
//----

I'd consider filling a bug report.