[webkit-efl] FW: Use of pimpl idiom for Ewk classes

[Dumez, Christophe]

>
> > You can already see it in my patch for the destination() getter. It has
> to return a "const char*" instead of a String because it is used by the C
> API.
> IMHO, external object(s) should treat Ewk classes as C++ as much as
> possible in this case.****
>
> Therefore, we don’t have to make functions that return char*.****
>
> Rather, caller can use utilization function to change String class to
> char*.****
>
> ** **
>
> --- Ewk class****
>
> String destination() { … }****
>
> --- Utilization function****
>
> char* StoCP(String s)****
>
> {****
>
>     char* cp = s.utf8().data();****
>
>     return cp;****
>
> }****
>
> --- C layer****
>
> void i_am_c_public_api()****
>
> {****
>
>     char* cp = StoCP(destination);****
>
> }
>

Eh what? This is wrong and will crash.

char* StoCP(String s) {
    char* cp = s.utf8().data(); // s.utf8() returns a temporary CString
object and you store a pointer to the internal representation of that
temporary CString object
    return cp; // You return a pointer to an area in memory that is no
longer valid because it was temporary.
}

Secondly, even if that worked, we loose all benefit of Eina Stringsharing
since we would return raw char* to the client.

Kr,
-- 
Christophe Dumez
Linux Software Engineer, PhD
Intel Finland Oy - Open Source Technology Center
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