Re: Forwarding constructor arguments to super

[bearophile]

pillsy:
 Is there a good way to forward constructor arguments to a superclass 
 constructor?

This seems to work for simple situations, but maybe it doesn't work in more 
complex cases:


import std.traits: ParameterTypeTuple;

mixin template This() {
this(ParameterTypeTuple!(super.__ctor) args) { super(args); }
}

class Foo {
int _x;
float _f;

this(int x, float f) {
this._x = x;
this._f = f;
}
}

class Bar : Foo {
mixin This;
}

void main() {
auto b = new Bar(10, 1.5);
}

Bye,
bearophile

Re: Minimize lock time

[Steven Schveighoffer]

On Thu, 10 Jun 2010 02:54:37 -0400, Kagamin s...@here.lot wrote:


Let's consider the following code:

synchronized(syncRoot)
{
  if(condition)opSuccess();
  else writeln(possibly,slow);
}

Suppose the else close doesn't need to be executed in lock domain and  
can be slow. How to minimize lock time here?


synchronized(syncRoot)
{
  if(condition)opSuccess();
  else goto Lwrite;
}
Lwrite: writeln(possibly,slow);

We can do this... but...


What about using a Mutex object?

mut.lock();
if(condition)
{
   scope(exit) mut.unlock();
   opSuccess();
}
else
{
   mut.unlock();
   writeln(possibly, slow);
}

I think it's in core.sync or something like that.  Mutex can even take  
over the standard monitor element of another object, so for instance you  
could assign it as the monitor of your syncRoot, so your other code that  
uses syncRoot and synchronized still works.


-Steve

Re: Arithmetic conversions and a surprise with 'max'

[Steven Schveighoffer]

On Fri, 11 Jun 2010 15:00:19 -0400, Ali Çehreli acehr...@yahoo.com wrote:

The following program demonstrates a problem that I just hit. It is a  
known gotcha of arithmetic conversion rules.


The program is trying to center some text around an index of a char  
array. To avoid negative index values, it calls 'max' to limit the  
starting offset at 0.


import std.algorithm;

void main()
{
 // An empty line
 char[10] line = ' ';

 // We want to center some text around the first quarter mark
 int center_of_text = line.length / 4;
 string text = 01234567;

 // To be safe, we want to limit the starting index at 0.
 // (No negative index please!)
 int start = max(0, center_of_text - text.length / 2);

 assert(start = 0); // FAILS!
}

The problem is due to converting the second argument of max to unsigned.


These kinds of things can typically be converted into a different form  
that removes the subtraction, or uses it in a safe way:


int start = center_of_text - min(center_of_text, text.length / 2);

-Steve

Re: undefined identifier with scope statement?

[Trass3r]

I'm going to guess that the given case is an accepts-invalid bug caused  
by scope getting re written as a try/finally with the writeln at the  
bottom of some scope containing res and the other cases put it outside  
the scope. File a bug and see what happens.


http://d.puremagic.com/issues/show_bug.cgi?id=4313

Re: Yet more OPTLINK woes

[torhu]

On 13.05.2010 21:07, torhu wrote:

On 13.05.2010 10:39, Daniel Keep wrote:

Attached both regular and decaffeinated^Hgutted versions.


Most likely DMD turns VisitorCtfe.d into an invalid object file. But
since you don't need to link with objects that contain only ctfe
functions...


http://d.puremagic.com/issues/show_bug.cgi?id=4315