• Paul D. Anderson (12/12) May 30 2013 Issue 4120 added an implicit cast for BigInt to a boolean value.
• bearophile (5/6) May 30 2013 For now don't make bigints constant. const=>mutable cast is not a
• Paul D. Anderson (10/16) May 30 2013 It's like the old joke: "Doc, it hurts when I do this." Doctor:
• bearophile (19/22) May 30 2013 And it's a good advice because:
• Paul D. Anderson (7/19) May 30 2013 This doesn't work either, by the way:

"Paul D. Anderson" <nobody hotmail.com> writes:

Issue 4120 added an implicit cast for BigInt to a boolean value.

This used to work:

/// Returns a mutable copy of a BigInt
public BigInt mutable(const BigInt num)
{
	BigInt big = cast(BigInt)num;
	return big;
}

But it now generates an error:

Error: template instance opCast!(BigInt) does not match template 
declaration opCast(T : bool)()

Is there another way to make a mutable copy of a BigInt?

"bearophile" <bearophileHUGS lycos.com> writes:

Paul D. Anderson:

 Is there another way to make a mutable copy of a BigInt?

For now don't make bigints constant. const=>mutable cast is not a 
good idea in general, in D.

Bye,
bearophile

"Paul D. Anderson" <nobody hotmail.com> writes:

On Thursday, 30 May 2013 at 22:57:20 UTC, bearophile wrote:
 Paul D. Anderson:

 Is there another way to make a mutable copy of a BigInt?

 For now don't make bigints constant. const=>mutable cast is not 
 a good idea in general, in D.

 Bye,
 bearophile

It's like the old joke: "Doc, it hurts when I do this." Doctor: 
"Don't do that!"

I need both constant and mutable BigInts.

I don't want to convert a constant value to mutable, I just want 
a mutable copy. The cast was just a way to make a mutable copy 
but it's broken now.

Other types have a .dup property which returns a mutable copy, 
but BigInt doesn't.

Paul

"bearophile" <bearophileHUGS lycos.com> writes:

Paul D. Anderson:

 It's like the old joke: "Doc, it hurts when I do this." Doctor: 
 "Don't do that!"

And it's a good advice because:
- The mammalian body is able to heal a surprisingly high number 
of problems by itself, given the right conditions and enough 
time. In such time avoiding to do "that" (like jumping on a knee 
that hurts) is a good advice, and it's often one of the 
conditions for the healing.
- Even if the body needs a bit of help from medicine, avoiding 
hurting a sore spot is often a good idea. Especially when there 
is no good cure available (like in many orthopaedic problems, 
that have surgery solutions that often cause more problems than 
the original problem).


 I need both constant and mutable BigInts.

Me too. In the last years I've put some bug reports on this in 
Bugzilla. Don is well aware that bigints are not const-corrected. 
It's a matter of working on them and fixing the problem, because 
maybe now D has all the tools to perform this fix/improvement.

In the meantime my advice is to not use const bigints.

Bye,
bearophile

"Paul D. Anderson" <nobody hotmail.com> writes:

On Thursday, 30 May 2013 at 22:32:08 UTC, Paul D. Anderson wrote:
 Issue 4120 added an implicit cast for BigInt to a boolean value.

 This used to work:

 /// Returns a mutable copy of a BigInt
 public BigInt mutable(const BigInt num)
 {
 	BigInt big = cast(BigInt)num;
 	return big;
 }

 But it now generates an error:

 Error: template instance opCast!(BigInt) does not match 
 template declaration opCast(T : bool)()

 Is there another way to make a mutable copy of a BigInt?

This doesn't work either, by the way:

     BigInt big = BigInt(num);

Error: template std.bigint.BigInt._ctor does not match any 
function template declaration. Candidates are:
... std.bigint.BigInt.__ctor(T : const(char)[](T s)
... std.bigint.BigInt.__ctor(T x) if (isIntegral!(T))