Overriding in operator
I'm writing a collection with functionality for membership checking. I
thought it would be nice to use the in operator. In the docs for
std.collections I surmise that this is the standard way to go. From the
source code, I see there's no special opIn, but that it can be done
with the more general...
bool opBinary(string op)(T k) if (op == in) {
...
}
Here T is, of course, a compile-time argument of the surrounding struct
or class.
So ... this is used in the the Phobos source in the DMD 2.052 distro
(if I'm not mistaken), but I can't get dmd 2.052 to accept it? I keep
getting the error message Error: rvalue of in expression must be an
associative array, not Foo!(uint).
I guess either that this is a recent feature -- I didn't see it
mentioned in Andrei's book -- and that my Phobos source is too recent
for my dmd ... or that I'm doing something wrong elsewhere in my code,
preventing the operator overloading to take force.
Suggestions/solutions?-)
--
Magnus Lie Hetland
http://hetland.org
Re: Overriding in operator
Am 04.03.2011 17:01, schrieb Magnus Lie Hetland:
I'm writing a collection with functionality for membership checking. I
thought it would be nice to use the in operator. In the docs for
std.collections I surmise that this is the standard way to go. From the
source code, I see there's no special opIn, but that it can be done with
the more general...
bool opBinary(string op)(T k) if (op == in) {
...
}
Here T is, of course, a compile-time argument of the surrounding struct
or class.
So ... this is used in the the Phobos source in the DMD 2.052 distro (if
I'm not mistaken), but I can't get dmd 2.052 to accept it? I keep
getting the error message Error: rvalue of in expression must be an
associative array, not Foo!(uint).
I guess either that this is a recent feature -- I didn't see it
mentioned in Andrei's book -- and that my Phobos source is too recent
for my dmd ... or that I'm doing something wrong elsewhere in my code,
preventing the operator overloading to take force. Suggestions/solutions?-)
If you try to use it in the manner of `something in
classWhichDefinesThisOpBinary` then it doesn't work because operator
overloading normally overloads on the left operand (ie something). Use
opBinaryRight(string op)(...) if(...) to get it working.
Mafi
Re: Overriding in operator
On 2011-03-04 17:06:29 +0100, Mafi said: If you try to use it in the manner of `something in classWhichDefinesThisOpBinary` then it doesn't work because operator overloading normally overloads on the left operand (ie something). Use opBinaryRight(string op)(...) if(...) to get it working. Aaah. That makes sense. And works. *But*: I copied my code from Phobos :D If you search for in, with the quotes, in std/container.d, you'll find two occurrences. The actual live use (in RedBlackTree) is opBinaryRight (which makes sense), but in the dummy class, TotalContainer, which is described as an unimplemented container that illustrates a host of primitives that a container may define, uses just opBinary. The doc-comment says that $(D k in container) returns true if the given key is in the container. So ... a bug, I guess? (One that isn't really executed -- but still...) Worth reporting? Anwyay: Thanks for the clarification :) -- Magnus Lie Hetland http://hetland.org
Re: Overriding in operator
Magnus Lie Hetland mag...@hetland.org wrote: On 2011-03-04 17:06:29 +0100, Mafi said: If you try to use it in the manner of `something in classWhichDefinesThisOpBinary` then it doesn't work because operator overloading normally overloads on the left operand (ie something). Use opBinaryRight(string op)(...) if(...) to get it working. Aaah. That makes sense. And works. *But*: I copied my code from Phobos :D If you search for in, with the quotes, in std/container.d, you'll find two occurrences. The actual live use (in RedBlackTree) is opBinaryRight (which makes sense), but in the dummy class, TotalContainer, which is described as an unimplemented container that illustrates a host of primitives that a container may define, uses just opBinary. The doc-comment says that $(D k in container) returns true if the given key is in the container. So ... a bug, I guess? (One that isn't really executed -- but still...) Worth reporting? Anwyay: Thanks for the clarification :) Definitely report it. -- Simen
Re: Overriding in operator
On 03/04/2011 05:01 PM, Magnus Lie Hetland wrote:
I'm writing a collection with functionality for membership checking. I thought
it would be nice to use the in operator. In the docs for std.collections I
surmise that this is the standard way to go. From the source code, I see
there's no special opIn, but that it can be done with the more general...
bool opBinary(string op)(T k) if (op == in) {
...
}
Here T is, of course, a compile-time argument of the surrounding struct or
class.
So ... this is used in the the Phobos source in the DMD 2.052 distro (if I'm
not mistaken), but I can't get dmd 2.052 to accept it? I keep getting the error
message Error: rvalue of in expression must be an associative array, not
Foo!(uint).
I guess either that this is a recent feature -- I didn't see it mentioned in
Andrei's book -- and that my Phobos source is too recent for my dmd ... or that
I'm doing something wrong elsewhere in my code, preventing the operator
overloading to take force. Suggestions/solutions?-)
Didn't even know 'in' can be defined with opBinary...
I use opIn_r ('r' for right side, since the container stand on the right of the
expression) everywhere, and it works fine.
Denis
--
_
vita es estrany
spir.wikidot.com
Re: Overriding in operator
On 2011-03-04 18:08:08 +0100, spir said:
Didn't even know 'in' can be defined with opBinary...
I use opIn_r ('r' for right side, since the container stand on the
right of the expression) everywhere, and it works fine.
Huh. Cool. Works like a charm. Seems cleaner like the opBinaryRight
solution, really. I just didn't know of it :)
--
Magnus Lie Hetland
http://hetland.org
Re: Overriding in operator
On 03/04/2011 10:41 AM, Magnus Lie Hetland wrote:
On 2011-03-04 18:08:08 +0100, spir said:
Didn't even know 'in' can be defined with opBinary...
I use opIn_r ('r' for right side, since the container stand on the
right of the expression) everywhere, and it works fine.
Huh. Cool. Works like a charm. Seems cleaner like the opBinaryRight
solution, really. I just didn't know of it :)
It can be seen on the D1 documentation:
http://www.digitalmars.com/d/1.0/operatoroverloading.html
That is (or will be) deprecated in D2.
Ali
