Overload a class constructor that takes an rvalue reference
I would like to do something like the following:
class Foo
{
Foo(int &&a, int b, std::string s="");
// does not compile because a is not an rvalue:
// Foo(int &&a, std::string s) : Foo(a, 0, s) {}
Foo(int &&a, std::string s) : Foo(std::move(a), 0, s) {} // move a
}
- Is this a valid way to overload a constructor in general?
- And specifically one that takes an rvalue reference as a parameter?
Edited based on comments
To clarify, I'm new to move semantics (and an amateur programmer) and I'm simply not sure if this is a good way to handle this situation.
I added the first question based on a comment (now deleted) that suggested this is not the correct way to overload constructors.
c++ move-semantics rvalue-reference constructor-overloading stdmove
asked Nov 17 '18 at 17:57
bur
17713
add a comment |
I would like to do something like the following:
class Foo
{
Foo(int &&a, int b, std::string s="");
// does not compile because a is not an rvalue:
// Foo(int &&a, std::string s) : Foo(a, 0, s) {}
Foo(int &&a, std::string s) : Foo(std::move(a), 0, s) {} // move a
}
- Is this a valid way to overload a constructor in general?
- And specifically one that takes an rvalue reference as a parameter?
Edited based on comments
To clarify, I'm new to move semantics (and an amateur programmer) and I'm simply not sure if this is a good way to handle this situation.
I added the first question based on a comment (now deleted) that suggested this is not the correct way to overload constructors.
c++ move-semantics rvalue-reference constructor-overloading stdmove
asked Nov 17 '18 at 17:57
bur
17713
2
Why don't you want to usestd::move? What do you mean by "better"?
– Rakete1111
Nov 17 '18 at 17:59
2
If it did compile, the default argument would make which constructor to call ambiguous.
– Neil Butterworth
Nov 17 '18 at 18:01
2
As you already recognizedstd::moveis the right way to do it.
– Werner Henze
Nov 17 '18 at 18:01
Thanks for your comments. I've edited the question accordingly. @Ripi2 I'll look into what is.
– bur
Nov 17 '18 at 18:07
add a comment |
I would like to do something like the following:
class Foo
{
Foo(int &&a, int b, std::string s="");
// does not compile because a is not an rvalue:
// Foo(int &&a, std::string s) : Foo(a, 0, s) {}
Foo(int &&a, std::string s) : Foo(std::move(a), 0, s) {} // move a
}
- Is this a valid way to overload a constructor in general?
- And specifically one that takes an rvalue reference as a parameter?
Edited based on comments
To clarify, I'm new to move semantics (and an amateur programmer) and I'm simply not sure if this is a good way to handle this situation.
I added the first question based on a comment (now deleted) that suggested this is not the correct way to overload constructors.
c++ move-semantics rvalue-reference constructor-overloading stdmove
asked Nov 17 '18 at 17:57
bur
17713
I would like to do something like the following:
class Foo
{
Foo(int &&a, int b, std::string s="");
// does not compile because a is not an rvalue:
// Foo(int &&a, std::string s) : Foo(a, 0, s) {}
Foo(int &&a, std::string s) : Foo(std::move(a), 0, s) {} // move a
}
- Is this a valid way to overload a constructor in general?
- And specifically one that takes an rvalue reference as a parameter?
Edited based on comments
To clarify, I'm new to move semantics (and an amateur programmer) and I'm simply not sure if this is a good way to handle this situation.
I added the first question based on a comment (now deleted) that suggested this is not the correct way to overload constructors.
c++ move-semantics rvalue-reference constructor-overloading stdmove
c++ move-semantics rvalue-reference constructor-overloading stdmove
asked Nov 17 '18 at 17:57
bur
17713
asked Nov 17 '18 at 17:57
bur
17713
edited Nov 17 '18 at 18:33
asked Nov 17 '18 at 17:57
bur
17713
asked Nov 17 '18 at 17:57
bur
17713
asked Nov 17 '18 at 17:57
bur
17713
17713
2
Why don't you want to usestd::move? What do you mean by "better"?
– Rakete1111
Nov 17 '18 at 17:59
2
If it did compile, the default argument would make which constructor to call ambiguous.
– Neil Butterworth
Nov 17 '18 at 18:01
2
As you already recognizedstd::moveis the right way to do it.
– Werner Henze
Nov 17 '18 at 18:01
Thanks for your comments. I've edited the question accordingly. @Ripi2 I'll look into what is.
– bur
Nov 17 '18 at 18:07
add a comment |
2
Why don't you want to usestd::move? What do you mean by "better"?
– Rakete1111
Nov 17 '18 at 17:59
2
If it did compile, the default argument would make which constructor to call ambiguous.
– Neil Butterworth
Nov 17 '18 at 18:01
2
As you already recognizedstd::moveis the right way to do it.
– Werner Henze
Nov 17 '18 at 18:01
Thanks for your comments. I've edited the question accordingly. @Ripi2 I'll look into what is.
– bur
Nov 17 '18 at 18:07
2
2
Why don't you want to use
std::move? What do you mean by "better"?– Rakete1111
Nov 17 '18 at 17:59
Why don't you want to use
std::move? What do you mean by "better"?– Rakete1111
Nov 17 '18 at 17:59
2
2
If it did compile, the default argument would make which constructor to call ambiguous.
– Neil Butterworth
Nov 17 '18 at 18:01
If it did compile, the default argument would make which constructor to call ambiguous.
– Neil Butterworth
Nov 17 '18 at 18:01
2
2
As you already recognized
std::move is the right way to do it.– Werner Henze
Nov 17 '18 at 18:01
As you already recognized
std::move is the right way to do it.– Werner Henze
Nov 17 '18 at 18:01
Thanks for your comments. I've edited the question accordingly. @Ripi2 I'll look into what is.
– bur
Nov 17 '18 at 18:07
Thanks for your comments. I've edited the question accordingly. @Ripi2 I'll look into what is.
– bur
Nov 17 '18 at 18:07
add a comment |
1 Answer
1
active
oldest
votes
Is this a valid way to overload a constructor in general?
And specifically one that takes an rvalue reference as a parameter?
It is valid to overload constructors in general, even ones that have rvalue reference arguments.
In particular, your example is ill-formed. As you point out in the comments, the example fails to compile. To fix it, you must pass an rvalue to the constructor that you delegate to. The correct way to convert a rvalue reference variable into an rvalue is to use std::move. So, what you must do is what you already know:
The only option I can see is to
std::move(a).
answered Nov 17 '18 at 18:12
eerorika
76.9k556117
To future readers: I edited the question before I saw this answer. Thanks, this answers my second question, and I can infer that the answer to my first question is yes.
– bur
Nov 17 '18 at 18:19
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Is this a valid way to overload a constructor in general?
And specifically one that takes an rvalue reference as a parameter?
It is valid to overload constructors in general, even ones that have rvalue reference arguments.
In particular, your example is ill-formed. As you point out in the comments, the example fails to compile. To fix it, you must pass an rvalue to the constructor that you delegate to. The correct way to convert a rvalue reference variable into an rvalue is to use std::move. So, what you must do is what you already know:
The only option I can see is to
std::move(a).
answered Nov 17 '18 at 18:12
eerorika
76.9k556117
To future readers: I edited the question before I saw this answer. Thanks, this answers my second question, and I can infer that the answer to my first question is yes.
– bur
Nov 17 '18 at 18:19
add a comment |
Is this a valid way to overload a constructor in general?
And specifically one that takes an rvalue reference as a parameter?
It is valid to overload constructors in general, even ones that have rvalue reference arguments.
In particular, your example is ill-formed. As you point out in the comments, the example fails to compile. To fix it, you must pass an rvalue to the constructor that you delegate to. The correct way to convert a rvalue reference variable into an rvalue is to use std::move. So, what you must do is what you already know:
The only option I can see is to
std::move(a).
answered Nov 17 '18 at 18:12
eerorika
76.9k556117
To future readers: I edited the question before I saw this answer. Thanks, this answers my second question, and I can infer that the answer to my first question is yes.
– bur
Nov 17 '18 at 18:19
add a comment |
Is this a valid way to overload a constructor in general?
And specifically one that takes an rvalue reference as a parameter?
It is valid to overload constructors in general, even ones that have rvalue reference arguments.
In particular, your example is ill-formed. As you point out in the comments, the example fails to compile. To fix it, you must pass an rvalue to the constructor that you delegate to. The correct way to convert a rvalue reference variable into an rvalue is to use std::move. So, what you must do is what you already know:
The only option I can see is to
std::move(a).
answered Nov 17 '18 at 18:12
eerorika
76.9k556117
Is this a valid way to overload a constructor in general?
And specifically one that takes an rvalue reference as a parameter?
It is valid to overload constructors in general, even ones that have rvalue reference arguments.
In particular, your example is ill-formed. As you point out in the comments, the example fails to compile. To fix it, you must pass an rvalue to the constructor that you delegate to. The correct way to convert a rvalue reference variable into an rvalue is to use std::move. So, what you must do is what you already know:
The only option I can see is to
std::move(a).
answered Nov 17 '18 at 18:12
eerorika
76.9k556117
answered Nov 17 '18 at 18:12
eerorika
76.9k556117
answered Nov 17 '18 at 18:12
eerorika
76.9k556117
answered Nov 17 '18 at 18:12
eerorika
76.9k556117
76.9k556117
To future readers: I edited the question before I saw this answer. Thanks, this answers my second question, and I can infer that the answer to my first question is yes.
– bur
Nov 17 '18 at 18:19
add a comment |
To future readers: I edited the question before I saw this answer. Thanks, this answers my second question, and I can infer that the answer to my first question is yes.
– bur
Nov 17 '18 at 18:19
To future readers: I edited the question before I saw this answer. Thanks, this answers my second question, and I can infer that the answer to my first question is yes.
– bur
Nov 17 '18 at 18:19
To future readers: I edited the question before I saw this answer. Thanks, this answers my second question, and I can infer that the answer to my first question is yes.
– bur
Nov 17 '18 at 18:19
add a comment |
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2
Why don't you want to use
std::move? What do you mean by "better"?– Rakete1111
Nov 17 '18 at 17:59
2
If it did compile, the default argument would make which constructor to call ambiguous.
– Neil Butterworth
Nov 17 '18 at 18:01
2
As you already recognized
std::moveis the right way to do it.– Werner Henze
Nov 17 '18 at 18:01
Thanks for your comments. I've edited the question accordingly. @Ripi2 I'll look into what is.
– bur
Nov 17 '18 at 18:07