• d coder (8/8) Sep 06 2011 Greetings
• Timon Gehr (3/11) Sep 06 2011 That is currently impossible. =/
• Brad Roberts (6/20) Sep 06 2011 Normally I try to avoid nit picking phrasing in public forums, but in
• Timon Gehr (4/22) Sep 07 2011 I never said there was. I wanted to express I wish there was.
• Trass3r (3/7) Sep 06 2011 What are you trying to do?
• Timon Gehr (3/10) Sep 06 2011 Which is a fancy way of returning an int. Probably he wants to implement...
• d coder (9/19) Sep 06 2011 Actually not expression templates. I am porting a BDD (Binary decision
• d coder (5/10) Sep 06 2011 Excuse my poor knowledge of expression templates. It seems I am doing

d coder <dlang.coder gmail.com> writes:

Greetings

It seems D assumes that these operators should return a bool value.
For example=C2=A0a < b is re-written as=C2=A0a.=E2=80=8BopCmp(b) < 0.
In my application, I wanted to overload comparison and equality
operators to return user defined values. Is that possible in D? If so
how?

Regards
- Puneet

Timon Gehr <timon.gehr gmx.ch> writes:

On 09/06/2011 04:13 PM, d coder wrote:
 Greetings

 It seems D assumes that these operators should return a bool value.
 For example a<  b is re-written as a.​opCmp(b)<  0.
 In my application, I wanted to overload comparison and equality
 operators to return user defined values. Is that possible in D? If so
 how?

 Regards
 - Puneet

That is currently impossible. =/
You'll have to use named member functions, eg. less, greater and equal.

Brad Roberts <braddr puremagic.com> writes:

On Tuesday, September 06, 2011 9:09:06 AM, Timon Gehr wrote:
 On 09/06/2011 04:13 PM, d coder wrote:
 Greetings

 It seems D assumes that these operators should return a bool value.
 For example a<  b is re-written as a.​opCmp(b)<  0.
 In my application, I wanted to overload comparison and equality
 operators to return user defined values. Is that possible in D? If so
 how?

 Regards
 - Puneet

 
 That is currently impossible. =/
 You'll have to use named member functions, eg. less, greater and equal.

Normally I try to avoid nit picking phrasing in public forums, but in 
this case it's important.  It's not just 'currently' impossible, it's 
by design with no intention to change.

Later,
Brad

Timon Gehr <timon.gehr gmx.ch> writes:

On 09/07/2011 05:28 AM, Brad Roberts wrote:
 On Tuesday, September 06, 2011 9:09:06 AM, Timon Gehr wrote:
 On 09/06/2011 04:13 PM, d coder wrote:
 Greetings

 It seems D assumes that these operators should return a bool value.
 For example a<   b is re-written as a.​opCmp(b)<   0.
 In my application, I wanted to overload comparison and equality
 operators to return user defined values. Is that possible in D? If so
 how?

 Regards
 - Puneet

 That is currently impossible. =/
 You'll have to use named member functions, eg. less, greater and equal.

 Normally I try to avoid nit picking phrasing in public forums, but in
 this case it's important.  It's not just 'currently' impossible,

not 'just' currently, but I never said 'just'. ;)

 it's by design with no intention to change.


I never said there was. I wanted to express I wish there was.


Timon

Trass3r <un known.com> writes:

 For example a < b is re-written as a.=E2=80=8BopCmp(b) < 0.
 In my application, I wanted to overload comparison and equality
 operators to return user defined values. Is that possible in D? If so
 how?

What are you trying to do?
In the end opCmp can return any value or object that works in the  =

rewritten case 'a.opCmp(b) < 0'.

Timon Gehr <timon.gehr gmx.ch> writes:

On 09/06/2011 07:21 PM, Trass3r wrote:
 For example a < b is re-written as a.​opCmp(b) < 0.
 In my application, I wanted to overload comparison and equality
 operators to return user defined values. Is that possible in D? If so
 how?

 What are you trying to do?
 In the end opCmp can return any value or object that works in the
 rewritten case 'a.opCmp(b) < 0'.

Which is a fancy way of returning an int. Probably he wants to implement 
expression templates.

d coder <dlang.coder gmail.com> writes:

 For example a < b is re-written as a.opCmp(b) < 0.
 In my application, I wanted to overload comparison and equality
 operators to return user defined values. Is that possible in D? If so
 how?

 What are you trying to do?
 In the end opCmp can return any value or object that works in the
 rewritten case 'a.opCmp(b) < 0'.

 Which is a fancy way of returning an int. Probably he wants to implement
 expression templates.

Actually not expression templates. I am porting a BDD (Binary decision
diagrams) library from C++ to D. The comparison operators are just
implemented as relations that return another BDD. A BDD would then
evaluate to 0 or 1 depending on many other factors and other BDDs. A
BDD actually represents a node on an acyclic graph.

Being able to overload comparison operators more generically would
have helped. For now I am using named functions as Timon suggested.

Regards
- Puneet

d coder <dlang.coder gmail.com> writes:

 Actually not expression templates. I am porting a BDD (Binary decision
 diagrams) library from C++ to D. The comparison operators are just
 implemented as relations that return another BDD. A BDD would then
 evaluate to 0 or 1 depending on many other factors and other BDDs. A
 BDD actually represents a node on an acyclic graph.

Excuse my poor knowledge of expression templates. It seems I am doing
something similar to expression templates, but not at meta-programming
level.

Regards
- Puneet