Protected object which never get finalized
in [ADA]
|
Prev: Initialization and Finalization of limited object "returned" by afunction
Next: FunnelWeb's tutorial comes with an Ada example
From: Hibou57 (Yannick Duchêne) on 12 Feb 2010 19:45 Hi, I may be not lucky : after the case of an object of a protected type being finalized too much soon, here is now that I have to do with an object of a protected type which never gets finalized (think I was to use this latter as a work around after long try failure with the former, I'm really not lucky at all). Inquisitive peoples with interests in the case, may have a look at the following test : two protected types are defined, with exact equivalent definition. One is defined in a package, the other is defined in the local scope. An instance of the first (the one defined in the package), never get finalized. An instance of the second type (declared in the local scope), goes through its normal life. But perhaps there's something I did not understood with Ada.Text_IO; with Ada.Finalization; procedure Test is -- This test program exposes a protected -- object which is initialized, but never -- get finalized (object of type A_Type). -- Don't care starting here if you just want to -- have a quick look, jump to the comment -- "Important things starts here" later below. package Spies is type Instance_Type (Client_Name : access String) is limited private; private type Instance_Type (Client_Name : access String) is new Ada.Finalization.Limited_Controlled with null record; overriding procedure Initialize (Instance : in out Instance_Type); overriding procedure Finalize (Instance : in out Instance_Type); end Spies; package body Spies is overriding procedure Initialize (Instance : in out Instance_Type) is Me : Instance_Type renames Instance; begin Ada.Text_IO.Put_Line ("Spy : I am coping with Initialization of " & Me.Client_Name.all & "."); end; overriding procedure Finalize (Instance : in out Instance_Type) is Me : Instance_Type renames Instance; begin Ada.Text_IO.Put_Line ("Spy : I am coping with Finalization of " & Me.Client_Name.all & "."); end; end Spies; -- Important things starts here package P is type A_Type is limited private; private protected type A_Type is private Spy : Spies.Instance_Type (Client_Name => new String'("P.A_Type")); end; end P; package body P is protected body A_Type is end; end P; protected type B_Type is private Spy : Spies.Instance_Type (Client_Name => new String'("B_Type")); end; protected body B_Type is end; begin declare Tested_Object : P.A_Type; begin Ada.Text_IO.Put_Line ("Inside block testing A_Type"); -- Tested_Object is initialized, but never -- get finalized, while [ARM 7.6.1(8)] requires -- finalization for protected types. Or am I wrong ? end; Ada.Text_IO.New_Line; declare Tested_Object : B_Type; begin Ada.Text_IO.Put_Line ("Inside block testing B_Type"); -- This one, with a strictly equivalent declaration, which -- is just not declared inside a package, get finalized -- as expected. end; end Test;
From: John B. Matthews on 14 Feb 2010 07:35 In article <op.u71i2edlvwnd5a(a)garhos>, Hibou57 (Yannick Duchêne) <yannick_duchene(a)yahoo.fr> wrote: > I may be not lucky : after the case of an object of a protected type > being finalized too much soon, here is now that I have to do with an > object of a protected type which never gets finalized (think I was > to use this latter as a work around after long try failure with the > former, I'm really not lucky at all). > > Inquisitive peoples with interests in the case, may have a look at > the following test : two protected types are defined, with exact > equivalent definition. One is defined in a package, the other is > defined in the local scope. An instance of the first (the one > defined in the package), never get finalized. An instance of the > second type (declared in the local scope), goes through its normal > life. > > But perhaps there's something I did not understood I get the same result with gcc 4.3.4, but it works if protected type A_Type is public in P: package P is protected type A_Type is private Spy : Spies.Instance_Type (Client_Name => new String'("P.A_Type")); end; end P; Type A_Type has its own private part, and this seems more comparable to the declaration of protected type B_Type. Is there any reason to make A_Type more opaque? -- John B. Matthews trashgod at gmail dot com <http://sites.google.com/site/drjohnbmatthews>
From: sjw on 15 Feb 2010 13:08 On Feb 14, 12:35 pm, "John B. Matthews" <nos...(a)nospam.invalid> wrote: > I get the same result with gcc 4.3.4, but it works if protected type > A_Type is public in P: > > package P is > protected type A_Type is > private > Spy : Spies.Instance_Type > (Client_Name => new String'("P.A_Type")); > end; > end P; > > Type A_Type has its own private part, and this seems more comparable to > the declaration of protected type B_Type. Is there any reason to make > A_Type more opaque? I had wanted to write private Name : aliased constant String := "P.A_Type"; protected type A_Type is private Spy : Spies.Instance_Type (Client_Name => Name'Access); end; end P; to avoid allocating a new Client_Name at each instance creation. This looks a little messy if in the public part.
From: Hibou57 (Yannick Duchêne) on 15 Feb 2010 14:20 Le Sun, 14 Feb 2010 13:35:47 +0100, John B. Matthews <nospam(a)nospam.invalid> a écrit: > Type A_Type has its own private part, and this seems more comparable to > the declaration of protected type B_Type. Is there any reason to make > A_Type more opaque? > Well, let say first I don't like the idea of designing with a compiler bug is mind, and secondly, this is not to be part of a public part (I don't really like private stuff in public part). When I know a mostly clean workaround, that's Ok, but I do not like this one. TBH, as was trying (as explained in the initial post), to workaround another bug when I meet this one. The interesting point to me, is that you get the same, so it is not just my compiler. This means for me I should report the bug to AdaCore (as you seem to have confirmed the bug). I thank you for the test you've made :) -- No-no, this isn't an oops ...or I hope (TM) - Don't blame me... I'm just not lucky
From: Hibou57 (Yannick Duchêne) on 15 Feb 2010 14:22
Le Mon, 15 Feb 2010 19:08:18 +0100, sjw <simon.j.wright(a)mac.com> a écrit: > I had wanted to write > > private > Name : aliased constant String := "P.A_Type"; > protected type A_Type is > private > Spy : Spies.Instance_Type > (Client_Name => Name'Access); > end; > end P; > > to avoid allocating a new Client_Name at each instance creation. Don't bother, this String is just required for the Spy member, which was just there to test how things was working. This was not to be part of the final application. > This looks a little messy if in the public part. Yes, ;) -- No-no, this isn't an oops ...or I hope (TM) - Don't blame me... I'm just not lucky |