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digitalmars.D.learn - How can I use heapify in safe code?

reply Burt <burt burt.burt> writes:
Hi,
I'd like to use a binary heap from  safe code. I thought  safe is 
transitive but the following example does not compile:

import std.container.binaryheap;
 safe // This makes things fail.
unittest
{
	// Test range interface.
	import std.algorithm.comparison : equal;
	int[] a = [4, 1, 3, 2, 16, 9, 10, 14, 8, 7];
	auto h = heapify(a);
	assert(h.equal([16, 14, 10, 9, 8, 7, 4, 3, 2, 1]));
}

Is there a way to  safely call heapify? How?

Thanks in advance!
Oct 01 2016
parent reply klmp <klmp nowhere.hu> writes:
On Saturday, 1 October 2016 at 16:59:18 UTC, Burt wrote:

 Hi,
 I'd like to use a binary heap from  safe code. I thought  safe 
 is transitive


It tries too but "heapify" uses the struct "BinaryHeap" that is 
not safe at all.
(either not annotated or  safe not applicable because of what it 
uses in intern:  system stuff)


 but the following example does not compile:

 import std.container.binaryheap;
  safe // This makes things fail.
 unittest
 {
 	// Test range interface.
 	import std.algorithm.comparison : equal;
 	int[] a = [4, 1, 3, 2, 16, 9, 10, 14, 8, 7];
 	auto h = heapify(a);
 	assert(h.equal([16, 14, 10, 9, 8, 7, 4, 3, 2, 1]));
 }

 Is there a way to  safely call heapify? How?


No easy "good" way:
1. BinaryHeap is an old container
2. It would require to patch the standard library. So virtually 
not available before weeks (but after a quick look it doesn't 
seem possible)

There's an easy "bad" way:

import std.container.binaryheap;
 safe // This makes things fail.
unittest
{
     void foo()  trusted
     {
	    import std.algorithm.comparison : equal;
	    int[] a = [4, 1, 3, 2, 16, 9, 10, 14, 8, 7];
	    auto h = heapify(a);
	    assert(h.equal([16, 14, 10, 9, 8, 7, 4, 3, 2, 1]));
     }
}

but "bad", don't forget ;)
It's a complete cheat to trust here.
Oct 01 2016
parent Burt <burt burt.burt> writes:
On Saturday, 1 October 2016 at 18:36:54 UTC, klmp wrote:

 On Saturday, 1 October 2016 at 16:59:18 UTC, Burt wrote:

 [...]


 It tries too but "heapify" uses the struct "BinaryHeap" that is 
 not safe at all.
 (either not annotated or  safe not applicable because of what 
 it uses in intern:  system stuff)


 [...]


 No easy "good" way:
 1. BinaryHeap is an old container
 2. It would require to patch the standard library. So virtually 
 not available before weeks (but after a quick look it doesn't 
 seem possible)

 There's an easy "bad" way:

 import std.container.binaryheap;
  safe // This makes things fail.
 unittest
 {
     void foo()  trusted
     {
 	    import std.algorithm.comparison : equal;
 	    int[] a = [4, 1, 3, 2, 16, 9, 10, 14, 8, 7];
 	    auto h = heapify(a);
 	    assert(h.equal([16, 14, 10, 9, 8, 7, 4, 3, 2, 1]));
     }
 }

 but "bad", don't forget ;)
 It's a complete cheat to trust here.


Thanks for your quick answer! In this case I'll try to rewrite 
BinaryHeap. The bad way came to my mind too :). But I don't like 
it as does not really make things  safer.
Oct 01 2016