Re: About %destructor is c++ mode

[Min Wang]

HI

Another dummy question:


How to I express


 exp: Exp1 "OR"  Exp
        | Exp1

in class if I do not use pointer?   I mean class Exp is just a pure
interface class?

class Exp {
}

class Elor : public Exp

{

public:

  Exp exp_1;   // if not a pointer?

  Exp exp_2;   // if not a pointer


  ~Elor() {}
}



Thanks.


min


On Thu, Aug 18, 2016 at 3:07 PM, Min Wang <address@hidden> wrote:

> Hi
>
> @Hans, thanks a lot!
>
> Could you explain more on  "reference count" ? do you mean
> std::shared_ptr?
>
>
>
> min
>
>
> On Thu, Aug 18, 2016 at 12:21 PM, Hans Åberg <address@hidden> wrote:
>
>>
>> > On 18 Aug 2016, at 18:07, Min Wang <address@hidden> wrote:
>>
>> > (1) when ListExp was returned up to PROG (e.g: PROG($1)), does it use
>> copy
>> > constructor? or
>> > use move constructor if it existed?
>>
>> A part from translation of the $-variables, the action code is copied
>> verbatim to the C++ parser. So do not think move constructors are invoked,
>> since that happens in special syntactic context where it is known that a
>> variable will perish.
>>
>> > (2) should I use object ( ListExp)  inside PROG class or  a
>> > std::unique_ptr inside the PROG to save some copy ? In the latter case,
>> > how can I initial std::unique_ptr if the passed parameters if a obj?
>>
>> Don’t use that, because in some cases there may be an implicit $$ = $1,
>> which might make it obsolete. Instead use a reference count or a GC, like
>> the Hans Boehm one:
>>   http://www.hboehm.info/gc/
>>
>>
>>
>
>
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>
>
>
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