Yu Feng wrote:
Hi Alex,
Fortunately I was dealing with the same problem too.
The key is for a property, you almost always want a weak string, and
manage the string in the object. In other words, this code will be fine:
public class Info.PersonInfo {
private string fio_;
public weak string fio {
get {
fio_ = get_fio();
return fio_;
I don't think that is safe.
You are returning a weak string, but the owner will free it before the
return actually happens.
I posted an example but it had some typos, I post a correct version
here:
private string _fio;
public weak string get_fio() {
if (_fio == null) {
_fio = "%s %C. %C".printf(l_name,f_name.get_char(),m_name.get_char());
}
return _fio;
}
the object will keep _fio for it's lifetime after which we *hope* all
weak references will have gone away.
I agree that it is problematic; part of the issue seems to be that
strings can't be reference counted and (apart from "weak") are also
immutable. The strdup's in generated code drive me mad.
I shall mention again that the talloc allocator not only ref-counts and
has owners but has destructors AND is type-safe. Talloc for string
management at least would make things much simpler. However it could
complicate transferring ownership to glib libraries which would use the
wrong free function.
I plan to do this anyway for samba.
The way out might be how Delphi handled conversion between String and
char*, when the string is cast to char* it get's strdup'd to a single
reference string (but ownership is not transferred, but could be).
It's not a complete solution, my thinking cap is still on.
Sam
}
}
public string get_fio(){
// bluh bluh bluh
}
}
I have to doubt that the memory management model for non-ref-counted
objects in VALA has some problem. I always go into trouble to use the
managed strings (string without weak), ending up with either compilation
failure or garbage C code that do a lot of useless strdup.
Yu
On Wed, 2008-08-20 at 19:46 +0400, Alexey Lubimov wrote:
public class Info.PersonInfo {
public string f_name;
public string m_name;
public string l_name;
public string fio {get {return this.get_fio();}}
public string get_fio() {
return "%s %C. %C".printf(l_name,f_name.get_char(),m_name.get_char());
}
}
PersonInfo.vala:12.7-12.28: error: Return value transfers ownership but
method return type hasn't been declared to transfer ownership
That's wrong?
any tips?
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