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digitalmars.D.bugs - [Issue 808] New: using properties as lvalues

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=808

           Summary: using properties as lvalues
           Product: D
           Version: 0.178
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Severity: enhancement
          Priority: P3
         Component: www.digitalmars.com
        AssignedTo: bugzilla digitalmars.com
        ReportedBy: thecybershadow gmail.com


I've been wondering - what is actually preventing us to operate with properties
like real lvalues? For example,

int[] array;
array.length++;      // Error: (array).length is not an lvalue
array.length += 2;   // Error: (array).length is not an lvalue

however,

array.length = array.length + 1; // works

Unless there's a fair reason of why this isn't viable, I'd suggest implementing
this.


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Jan 06 2007
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=808






Assigment to properties is actually call to some method which actually do other
operations (like reallocation). I think that
   p op= x,
properties operations should be defined as
  p = p op x

Also for user defined properties (if both setter and getter is availble, so
"lvalue-like" behaviour can be emulated in this way). Cases in which p += x,
should be performed differently can always be emulated by using wrapper
struct/class, which caries state and overloads opAddAssign. This cases are
rear, but still possible. (usefull for some highly optimized codes, or
synchronized/atomic changes, or loging actuall changes)



array.length *= 2;  is one of the most annoying :)


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Apr 02 2009
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=808


dsimcha yahoo.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ghaecker idworld.net





*** Bug 2949 has been marked as a duplicate of this bug. ***


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May 07 2009
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=808


Leandro Lucarella <leandro.lucarella sociomantic.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |leandro.lucarella sociomant
                   |                            |ic.com
            Version|0.178                       |D2



2012-05-31 04:36:03 PDT ---
This is a highly voted enhancement request but there is no "official" statement
about it. Would be nice to have some "official" comment for votes with so many
votes.

Is this intended to be implemented at all? Otherwise I guess is better to close
it with WONTFIX to decrese bugzilla's "noise".

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May 31 2012
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=808


Dmitry Olshansky <dmitry.olsh gmail.com> changed:

           What    |Removed                     |Added
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                 CC|                            |dmitry.olsh gmail.com



04:45:19 PDT ---
I'll fork the language if it's not fixed. 

And of course I'll seduce the whole Russian communitiy to follow suit ;)

Seriously, it's important. I've hit it like 10+ time just today.

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May 31 2012
prev sibling next sibling parent d-bugmail puremagic.com writes:
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Vladimir Panteleev <thecybershadow gmail.com> changed:

           What    |Removed                     |Added
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             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED



04:46:16 PDT ---
The examples in my original post, as well as Witold's "array.length *= 2", work
now.

This issue originally referred to built-in language properties, like .length.
The  property kind of properties can be lvalues if the getter returns an lvalue
- for example,  property ref int x() { return _x; }, or as Witold mentioned,
using wrapper types.

I think we can consider this bug as resolved today.

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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04:47:51 PDT ---
Thx Vladimir, I haven't tried ref return.
So silly.

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May 31 2012
prev sibling parent d-bugmail puremagic.com writes:
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Jonathan M Davis <jmdavisProg gmx.com> changed:

           What    |Removed                     |Added
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                 CC|                            |jmdavisProg gmx.com



PDT ---
And using ref with a property pretty much defeats its entire purpose, since
setting it ends up completely bypassing the getter. We really need to be able
to have stuff like prop++ work _without_ ref. But there's another enhancement


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May 31 2012