In Java one can write:

new MyClass().run();

in D this does not compile, parenthesis are needed.

(new MyClass()).run();

But why is the D language designed like that?

Reply to Frank,

> In Java one can write:
> 
> new MyClass().run();
> 
> in D this does not compile, parenthesis are needed.
> 
> (new MyClass()).run();
> 
> But why is the D language designed like that?
> 

vote++

"Frank Benoit" <keinfarbton@googlemail.com> wrote in message news:gtqf6c$8ma$1@digitalmars.com...
> In Java one can write:
>
> new MyClass().run();
>
> in D this does not compile, parenthesis are needed.
>
> (new MyClass()).run();
>
> But why is the D language designed like that?

I'm torn on this.

On one hand, I'm uncomfortable with having an operator that requires whitespaces bind tighter than an operator that isn't typically used with whitespace. To me, "new MyClass().run();" just *looks* like run() returns a type and you're trying to instantiate *that* type (with a default constructor).

But on the other hand, I can certainly see the practiclity of the Java version and I've frequently had reason to use "(new MyClass()).run();" in my own code.

BCS wrote:
> Reply to Frank,
> 
>> In Java one can write:
>>
>> new MyClass().run();
>>
>> in D this does not compile, parenthesis are needed.
>>
>> (new MyClass()).run();
>>
>> But why is the D language designed like that?
>>
> 
> vote++
> 
> 

me too... Bugzilla, anyone?

Robert Fraser schrieb:
> me too... Bugzilla, anyone?

http://d.puremagic.com/issues/show_bug.cgi?id=2945

On Wed, 06 May 2009 00:39:12 +0200, Frank Benoit wrote:

> In Java one can write:
> 
> new MyClass().run();
> 
> in D this does not compile, parenthesis are needed.
> 
> (new MyClass()).run();
> 
> But why is the D language designed like that?

So presumably if it was changed to behave as Java, to get the current functionality one would need to write ...

new (MyClass().run());

-- 
Derek Parnell
Melbourne, Australia
skype: derek.j.parnell

On Tue, May 5, 2009 at 8:49 PM, Derek Parnell <derek@psych.ward> wrote:

> So presumably if it was changed to behave as Java, to get the current functionality one would need to write ...
>
> new (MyClass().run());

Except that currently has no meaning, since you can't return a type from a function :P

Frank Benoit escribió:
> In Java one can write:
> 
> new MyClass().run();
> 
> in D this does not compile, parenthesis are needed.
> 
> (new MyClass()).run();
> 
> But why is the D language designed like that?

I think it's because the (already hated by many, including myself) ability to invoke a function (or a constructor) without parenthesis.

So:
  new MyClass.run
and
  new MyClass().run

should be the same, right?

But in the first case MyClass could be a package name and you are constructing a new "MyClass.run" instance. You could make them behave differently, but some would say it's not consistent, etc.

Frank Benoit Wrote:

> In Java one can write:
> 
> new MyClass().run();
> 
> in D this does not compile, parenthesis are needed.
> 
> (new MyClass()).run();
> 
> But why is the D language designed like that?

Related problem:

string str = "qwe rty uio";
string[] arr = str.split(" "); // works

class A {
    string foo() { return "qwe rty uio"; }
}
A a = new A;
a.foo.split(" "); // doesn't work

On Tue, 05 May 2009 21:43:54 -0400, Ary Borenszweig <ary@esperanto.org.ar> wrote:

> Frank Benoit escribió:
>> In Java one can write:
>>  new MyClass().run();
>>  in D this does not compile, parenthesis are needed.
>>  (new MyClass()).run();
>>  But why is the D language designed like that?
>
> I think it's because the (already hated by many, including myself) ability to invoke a function (or a constructor) without parenthesis.
>
> So:
>    new MyClass.run
> and
>    new MyClass().run
>
> should be the same, right?
>
> But in the first case MyClass could be a package name and you are constructing a new "MyClass.run" instance. You could make them behave differently, but some would say it's not consistent, etc.

If properties are every properly established, I hope the ability to call default constructors without having parens does not go away.  It's different than a property function call.

I would say it's ok to make them behave differently.  As others have said, we already have instances where you have to use parens to delineate where you are calling a function versus accessing a member.

For example, the (admittedly seldom used) chaining call of Stdout in Tango, if you want to insert a new line it's:

Stdout("hi")(4).newline()("hi");

Without the extra parens, it looks like you're trying to call newline with the argument "hi".

-Steve