• d-bugmail puremagic.com (40/40) May 04 2012 http://d.puremagic.com/issues/show_bug.cgi?id=8040
• d-bugmail puremagic.com (15/15) May 22 2012 http://d.puremagic.com/issues/show_bug.cgi?id=8040
• d-bugmail puremagic.com (9/16) May 23 2012 http://d.puremagic.com/issues/show_bug.cgi?id=8040
• d-bugmail puremagic.com (16/19) May 23 2012 http://d.puremagic.com/issues/show_bug.cgi?id=8040
• d-bugmail puremagic.com (10/23) May 23 2012 http://d.puremagic.com/issues/show_bug.cgi?id=8040
• d-bugmail puremagic.com (6/6) May 29 2012 http://d.puremagic.com/issues/show_bug.cgi?id=8040
• d-bugmail puremagic.com (9/9) May 31 2012 http://d.puremagic.com/issues/show_bug.cgi?id=8040

d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=8040

           Summary: writeln(null) too
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Keywords: rejects-valid
          Severity: normal
          Priority: P2
         Component: Phobos
        AssignedTo: nobody puremagic.com
        ReportedBy: bearophile_hugs eml.cc



Problem found by Ali Çehreli.

D2 code:


import std.stdio: writeln;
class Foo {}
struct Bar {}
void main() {
    Foo f = null;
    writeln(f);
    Bar* b = null;
    writeln(b);
    writeln(null);
}


Expected output similar to:

cast(Foo)null
cast(Bar*)null
null


DMD 2.056 prints "null" in the first two writeln, and gives errors for the
third one:

...\dmd2\src\phobos\std\stdio.d(1562): Error: undefined identifier 'length'
...\dmd2\src\phobos\std\stdio.d(1562): Error: undefined identifier 'ptr', did
you mean 'template tr(C1,C2,C3,C4 = immutable(char))'?
test.d(9): Error: template instance std.stdio.writeln!(typeof(null)) error
instantiating

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d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=8040


Kenji Hara <k.hara.pg gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |pull



https://github.com/D-Programming-Language/phobos/pull/599

With my pull, original code output is:
----
null
null
null

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d-bugmail puremagic.com writes:

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 https://github.com/D-Programming-Language/phobos/pull/599
 
 With my pull, original code output is:
 ----
 null
 null
 null

Thank you Kenji Hara, this is an improvement.

But isn't it better to add types (as in cast(Foo) or cast(Bar*)) to better tell
apart the three kinds of null in that example?

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d-bugmail puremagic.com writes:

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 But isn't it better to add types (as in cast(Foo) or cast(Bar*)) to better tell
 apart the three kinds of null in that example?

No, it isn't. It is consistent with other literal formatting.

writeln(1);  // prints "1", not "cast(int)1"
writeln(1L); // prints "1", not "cast(long)1"
writeln(1f); // prints "1", not "cast(float)1"

And, formatting as like cast syntax will make unfomatting complicate. It is
less benefit.

Furthermore, std.format module does not print value type in general.
(Deprecated typedef value was formatted like cast syntax, but I think it is
special case)

Therefore, I think your proposal has many faults than benefits.

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d-bugmail puremagic.com writes:

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 writeln(1);  // prints "1", not "cast(int)1"
 writeln(1L); // prints "1", not "cast(long)1"
 writeln(1f); // prints "1", not "cast(float)1"

In my opinion writeln(1f) and writeln(1.0L) should print 1.0, as in Python:

 int(1)



1
 float(1)



1.0


 And, formatting as like cast syntax will make unfomatting complicate. It is
 less benefit.
 
 Furthermore, std.format module does not print value type in general.
 (Deprecated typedef value was formatted like cast syntax, but I think it is
 special case)
 
 Therefore, I think your proposal has many faults than benefits.

OK. Thank you for the answers.

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d-bugmail puremagic.com writes:

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*** Issue 7866 has been marked as a duplicate of this issue. ***

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d-bugmail puremagic.com writes:

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Kenji Hara <k.hara.pg gmail.com> changed:

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


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