• Miguel Ferreira Simões (9/9) Apr 11 2005 Is this a bug?
• Ben Hinkle (5/12) Apr 11 2005 no - the stack of test(0), which contains num, is gone by the time the
• Miguel Ferreira Simões (1/4) Apr 11 2005 You are right! Thanks!
• Manfred Nowak (21/23) Apr 11 2005 According to the specs this behaviour _is_ buggy, because the specs
• Ben Hinkle (10/32) Apr 11 2005 I'm not sure what section you are looking at but if you have a suggestio...
• Sean Kelly (4/19) Apr 11 2005 Really? But the delegate is called before the function exits. I would ...
• Sean Kelly (4/25) Apr 11 2005 I take it back. I misread the return value for test. I thought it retu...

"Miguel Ferreira Simões" <Kobold netcabo.pt> writes:

Is this a bug?

 int delegate () test(int num) {

  return delegate int() {
   return num;
  };
 }

 writefln("num: ", test(0)());


-- 
Miguel Ferreira Simões 

"Ben Hinkle" <ben.hinkle gmail.com> writes:

"Miguel Ferreira Simões" <Kobold netcabo.pt> wrote in message 
news:d3dopj$28a2$1 digitaldaemon.com...
 Is this a bug?

 int delegate () test(int num) {

  return delegate int() {
   return num;
  };
 }

 writefln("num: ", test(0)());

no - the stack of test(0), which contains num, is gone by the time the 
delegate is called. You need to store num on the heap if you need it to live 
beyond the call to test(0). 

"Miguel Ferreira Simões" <Kobold netcabo.pt> writes:

 no - the stack of test(0), which contains num, is gone by the time the
 delegate is called. You need to store num on the heap if you need it to 
 live beyond the call to test(0).

You are right! Thanks! 

Manfred Nowak <svv1999 hotmail.com> writes:

"Ben Hinkle" <ben.hinkle gmail.com> wrote:

[...]
 the stack of test(0), which contains num, is gone by the
 time the delegate is called.

According to the specs this behaviour _is_ buggy, because the specs 
only make accesses to local _variables_ illegal, not to parameters.

But how about this:

<code>
import std.stdio;
void main(){
  int x=0; 
  int delegate () y;
  int delegate () test(inout int num) {
    y= delegate int() {
      return num;
    };
    return y;
  }
  writefln("num: ", test(x)());
}
</code>

Still wrong result.

-manfred

"Ben Hinkle" <ben.hinkle gmail.com> writes:

"Manfred Nowak" <svv1999 hotmail.com> wrote in message 
news:d3e3vo$2mqn$1 digitaldaemon.com...
 "Ben Hinkle" <ben.hinkle gmail.com> wrote:

 [...]
 the stack of test(0), which contains num, is gone by the
 time the delegate is called.

 According to the specs this behaviour _is_ buggy, because the specs
 only make accesses to local _variables_ illegal, not to parameters.

I'm not sure what section you are looking at but if you have a suggestion 
for clarifying the doc I'd add a note to the wiki for documentation 
feedback. About the specific issue I doubt Walter intends for D to have 
different lifetimes for local variables and parameters.

 But how about this:

 <code>
 import std.stdio;
 void main(){
  int x=0;
  int delegate () y;
  int delegate () test(inout int num) {
    y= delegate int() {
      return num;
    };
    return y;
  }
  writefln("num: ", test(x)());
 }
 </code>

 Still wrong result.

Correct. The delegate is still accessing the parameter "num". It doesn't 
matter that num is a pointer or reference to another location. To work 
properly the delegate can't refer to anything that is not on the stack when 
the delegate is called. 

Sean Kelly <sean f4.ca> writes:

In article <d3dpvd$29n6$1 digitaldaemon.com>, Ben Hinkle says...
"Miguel Ferreira Simões" <Kobold netcabo.pt> wrote in message 
news:d3dopj$28a2$1 digitaldaemon.com...
 Is this a bug?

 int delegate () test(int num) {

  return delegate int() {
   return num;
  };
 }

 writefln("num: ", test(0)());

no - the stack of test(0), which contains num, is gone by the time the 
delegate is called. You need to store num on the heap if you need it to live 
beyond the call to test(0). 

Really?  But the delegate is called before the function exits.  I would expect
the stack frame to be intact at this point.


Sean

Sean Kelly <sean f4.ca> writes:

In article <d3ehk4$61r$1 digitaldaemon.com>, Sean Kelly says...
In article <d3dpvd$29n6$1 digitaldaemon.com>, Ben Hinkle says...
"Miguel Ferreira Simões" <Kobold netcabo.pt> wrote in message 
news:d3dopj$28a2$1 digitaldaemon.com...
 Is this a bug?

 int delegate () test(int num) {

  return delegate int() {
   return num;
  };
 }

 writefln("num: ", test(0)());

no - the stack of test(0), which contains num, is gone by the time the 
delegate is called. You need to store num on the heap if you need it to live 
beyond the call to test(0). 

Really?  But the delegate is called before the function exits.  I would expect
the stack frame to be intact at this point.

I take it back.  I misread the return value for test.  I thought it returned an
int, not a delegate.


Sean