www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.bugs - [Issue 9120] New: Uniform construction for array types

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=9120

           Summary: Uniform construction for array types
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: k.hara.pg gmail.com


--- Comment #0 from Kenji Hara <k.hara.pg gmail.com> 2012-12-06 16:51:45 PST ---
Spin-off issue from bug 9112.

In current, array types does not have consistency between literal syntax and
`new` syntax.

void maiin() {
  // dynamic array
  int[] da1 = [1,2,3];  // literal syntax
//int[] da2 = int[](1,2,3);  // not allowed
    // because dynamic array is *always* allocated in heap?
  int[] da3 = new int[](3);  // heap-allocated int array has length 3.
    // but, all elements in da2 initialized with int.init.
    // we cannot give initializing elements in use of new syntax.
  int[] dax = new int[3];  // special syntax. This creates int[] has length 3.

  int[3] sa1 = [1,2,3];  // literal syntax
//int[3] sa2 = int[3](1,2,3);  // not allowed
//int[3]* sa3a = new int[3];  // impossible
  alias T = int[3];
//int[3]* sa3b = new T;.  // Error: new can only create structs, dynamic arrays
or class objects, not int[3u]'s
    // -> special syntax for dynamic array blocks this...

  int[string] aa1 = ["a":1, "b":2];  // literal syntax
//int[string] aa1 = int[string]("a":1, "b":2);  // not allowed
//int[string] aa2 = new int[string];  // not allowed
}

This is not serious language flaw, but I feel it is desirable which have
consistent syntax.

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Dec 06 2012
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=9120


bearophile_hugs eml.cc changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bearophile_hugs eml.cc


--- Comment #1 from bearophile_hugs eml.cc 2012-12-06 18:05:57 PST ---
What exactly are the syntax changes/additions are you suggesting?


I think this syntax is better to not support this syntax:
int[] da2 = int[](1,2,3);  // not allowed

-------------------

There are several design problems in the array syntax. Like:

Issue 3849
Issue 4703
Issue 7445


One maybe even bigger syntax problem is related to mixing fixed-sized arrays
and dynamic arrays. This is not supported (this means a dynamic array of fixed
arrays of dynamic arrays):

void main() {
    auto a = new int[][3][](5, 7);
}


Currently the D syntax to create such mixes is incomplete, and I think it's not
clear enough.

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Dec 06 2012
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=9120



--- Comment #2 from Kenji Hara <k.hara.pg gmail.com> 2012-12-06 18:45:36 PST ---
(In reply to comment #1)

 What exactly are the syntax changes/additions are you suggesting?


I'm not sure what is should be chosen. This is not an exact syntax proposal,
rather a suggestion to discuss about the issue.


 I think this syntax is better to not support this syntax:
 int[] da2 = int[](1,2,3);  // not allowed


I agree that supporting it (stack-allocated dynamic array) is much difficult.


 There are several design problems in the array syntax. Like:
 
 Issue 3849
 Issue 4703
 Issue 7445
 
 
 One maybe even bigger syntax problem is related to mixing fixed-sized arrays
 and dynamic arrays. This is not supported (this means a dynamic array of fixed
 arrays of dynamic arrays):
 
 void main() {
     auto a = new int[][3][](5, 7);
 }
 
 
 Currently the D syntax to create such mixes is incomplete, and I think it's not
 clear enough.


Thanks for presenting related issues.

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Dec 06 2012