class encapsulating reference

[John Goche]

Hello,

The class TRefByValue in the Symbian OS API
encapsulates a reference inside a class so that
it can be passed by value to functions. But why
would we want this? After all, if a function needs
to take a reference parameter, why code the
function to take TRefByValue as a value
parameter instead? I don't see any
advantage to this.

http://www.symbian.com/developer/techlib/v9.1docs/doc_source/reference/reference-cpp/N101CA/TRefByValueClass.html

Comments appreciated,

Thanks,

JG

[dasjotre]

Re: class encapsulating reference


John Goche wrote:

Hello,
>
The class TRefByValue in the Symbian OS API
encapsulates a reference inside a class so that
it can be passed by value to functions. But why
would we want this? After all, if a function needs
to take a reference parameter, why code the
function to take TRefByValue as a value
parameter instead? I don't see any
advantage to this.
>

http://www.symbian.com/developer/techlib/v9.1docs/doc_source/reference/reference-cpp/N101CA/TRefByValueClass.html

>
Comments appreciated,
>
Thanks,
>
JG

from boost::ref documentation:

"The purpose of boost::referenc e_wrapper<Tis to contain
a reference to an object of type T. It is primarily used to
"feed" references to function templates (algorithms)
that take their parameter by value."

[John Goche]

Re: class encapsulating reference

dasjotre wrote:

John Goche wrote:

Hello,

The class TRefByValue in the Symbian OS API
encapsulates a reference inside a class so that
it can be passed by value to functions. But why
would we want this? After all, if a function needs
to take a reference parameter, why code the
function to take TRefByValue as a value
parameter instead? I don't see any
advantage to this.

http://www.symbian.com/developer/techlib/v9.1docs/doc_source/reference/reference-cpp/N101CA/TRefByValueClass.html

Comments appreciated,

Thanks,

JG

>
from boost::ref documentation:
>
"The purpose of boost::referenc e_wrapper<Tis to contain
a reference to an object of type T. It is primarily used to
"feed" references to function templates (algorithms)
that take their parameter by value."

Thank you dasjotre for your reply.

However, I do not see the point in the definition of RTest::Printf for
example. See

http://www.symbian.com/developer/techlib/v9.1docs/doc_source/reference/reference-cpp/N101CA/RTestClass.html#%3a%3aRTest%3a%3aPrintf%28%29

Here the argument to Printf is not a templated parameter
passed by value as in the boost example you mentioned.
So why is the TDesC string parameter passed in this way?

Furthermore, what is the meaning of

operator &()

as found in TRefByValue? What does this do?

Thanks,

JG