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digitalmars.D.learn - A refinement for pure implementation

reply "bearophile" <bearophileHUGS lycos.com> writes:
Do you remember if Hara has implemented a patch to allow a2 to be 
immutable?


int[] foo1(int x) pure {
     return null;
}
int[] foo2(string s) pure {
     return null;
}
void main() {
     immutable a1 = foo1(10); // OK
     immutable a2 = foo2("hello"); // currently error
}


The idea behind this is that the type of s is different from the 
return type of foo2, so foo2 is a strongly pure function.

Bye,
bearophile
Nov 10 2012
next sibling parent reply Timon Gehr <timon.gehr gmx.ch> writes:
On 11/10/2012 03:32 PM, bearophile wrote:

 Do you remember if Hara has implemented a patch to allow a2 to be
 immutable?


 int[] foo1(int x) pure {
      return null;
 }
 int[] foo2(string s) pure {
      return null;
 }
 void main() {
      immutable a1 = foo1(10); // OK
      immutable a2 = foo2("hello"); // currently error
 }


 The idea behind this is that the type of s is different from the return
 type of foo2, so foo2 is a strongly pure function.

 Bye,
 bearophile



It is strongly pure regardless of potential aliasing in the return 
value. This is a bug.
Nov 10 2012
parent Timon Gehr <timon.gehr gmx.ch> writes:
On 11/10/2012 05:21 PM, bearophile wrote:

 Timon Gehr:


 It is strongly pure regardless of potential aliasing in the return
 value. This is a bug.



 This can't be strongly pure:


 int[] foo2(int[] a) pure {
      a[0]++;
      return a;
 }


 Bye,
 bearophile



The point was that the code you gave should work even without your 
proposed enhancement.
Nov 10 2012
prev sibling next sibling parent "bearophile" <bearophileHUGS lycos.com> writes:
Timon Gehr:


 It is strongly pure regardless of potential aliasing in the 
 return value. This is a bug.



This can't be strongly pure:


int[] foo2(int[] a) pure {
     a[0]++;
     return a;
}


Bye,
bearophile
Nov 10 2012
prev sibling parent "bearophile" <bearophileHUGS lycos.com> writes:
Timon Gehr:


 The point was that the code you gave should work even without 
 your proposed enhancement.



So my original question was: do you remember if Hara has already 
written a patch to fix that bug? :-)

Bye,
bearophile
Nov 10 2012