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digitalmars.D.learn - parameter-less "default" struct constructor not allowed--why?

reply Christopher the Magnificent <ultimatemacfanatic gmail.com> writes:
Why are parameter-less struct constructors not allowed?

I have a struct that doesn't need vtable or inheritance or anything, but 
I want to automatically call a method on it when it's created.

I also want to create this struct on the heap using operator "new".

Is there any way I can keep this struct as a struct (rather than a 
class) and still be able to allocate it and initialize it (including 
execution of my setup code) in a single statement, a la the following?
	
	MyStruct* ms = new MyStruct();

Maybe I'll have to introduce a dummy parameter in order to be include a 
struct constructor.  You think so?

What is the rationale to D's not permitting parameter-less "default" 
struct constructors?
May 20 2011
parent reply Andrej Mitrovic <andrej.mitrovich gmail.com> writes:
You can override opCall(). I don't know how people feel about using
that sort of thing, but it works for me (I rarely need it though).
May 20 2011
parent reply Christopher the Magnificent <ultimatemacfanatic gmail.com> writes:
On 5/20/11 4:25 PM, Andrej Mitrovic wrote:

 You can override opCall(). I don't know how people feel about using
 that sort of thing, but it works for me (I rarely need it though).


If I override opCall(), will I be able to use that will operator "new" 
to do BOTH of the following?

1.    MyStruct ms1 = MyStruct();  // calls opCall to initialize on stack
2.    MyStruct* ms2 = new MyStruct(); // calls opCall() to init on heap



What this suggests to me is that opCall override and using keyword "new" 
do not mix.  Would you agree?

This leads me back to my original question.

*Why* are zero-parameter struct constructors disallowed?  Any insight or 
speculation?

If there are no valid reasons for this limitation, then perhaps its 
ought to be lifted.

What do you think, Mr. Mitrovic, or anyone?

-- Christopher
May 20 2011
next sibling parent Andrej Mitrovic <andrej.mitrovich gmail.com> writes:
http://www.digitalmars.com/d/archives/digitalmars/D/Why_no_struct_default_constructors_129559.html
May 20 2011
prev sibling next sibling parent "Jonathan M Davis" <jmdavisProg gmx.com> writes:
 http://www.digitalmars.com/d/archives/digitalmars/D/Why_no_struct_default_c
 onstructors_129559.html


LOL. You just saved me a lot of typing. I was basically going to write out 
that post again...

- Jonathan M Davis
May 20 2011
prev sibling parent Andrej Mitrovic <andrej.mitrovich gmail.com> writes:
On 5/21/11, Jonathan M Davis <jmdavisProg gmx.com> wrote:

 http://www.digitalmars.com/d/archives/digitalmars/D/Why_no_struct_default_c
 onstructors_129559.html


 LOL. You just saved me a lot of typing. I was basically going to write out
 that post again...

 - Jonathan M Davis


You should keep a hash of all your posts which you can quickly look up
by key, retrieve the link and then just paste that as your response.

You could even do it in D, it has hashes! :p
May 20 2011