From: Tom Tromey <tom@tromey.com>
To: Simon Marchi <simon.marchi@polymtl.ca>
Cc: Tom Tromey <tom@tromey.com>, gdb-patches@sourceware.org
Subject: Re: [RFA 03/22] Use scoped_restore for ui_file
Date: Sat, 01 Oct 2016 05:22:00 -0000 [thread overview]
Message-ID: <87bmz4fxtt.fsf@tromey.com> (raw)
In-Reply-To: <7417a71f254c7f42026408c5e143b374@simark.ca> (Simon Marchi's message of "Sat, 01 Oct 2016 00:28:10 -0400")
>>>>> "Simon" == Simon Marchi <simon.marchi@polymtl.ca> writes:
Simon> shared_ptr< scoped_restore<ui_file *> > save_file;
Why shared_ptr and not unique_ptr?
Simon> We can't use std::shared_ptr, since it's only in c++11, but I think
Simon> it's just a matter of time before we define our own version of it.
... Pedro's branch has unique_ptr :)
Simon> An alternative would be to have a default constructor for
Simon> scoped_restore, that creates an inactive scoped_restore, and then
Simon> assign it a variable to restore later with acquire(T* var)/acquire(T*
Simon> var, T value) methods or something. I am not sure which one is
Simon> better.
FWIW Mozilla uses an Option class for this kind of thing.
It works like:
Option< scoped_restore<ui_file *> > save_file;
if (mumble) {
save_file.emplace (make_scoped_restore (&var));
}
The main advantage of this over *_ptr is that Option contains the
object, so no heap allocations are required.
Simon> To support some use cases where discard_cleanups is used, we might
Simon> need a way to "release" the scoped_restore, which would essentially
Simon> cancel it. So if we have a "release" method, maybe having the
Simon> symmetrical "acquire" would make sense.
Simon> What do you think?
It seems sensible to me.
One idea to consider is whether it's better to have a separate
"discardable" variant of scoped_restore (or whatever else); the idea
being that then the type name serves as a signal to look more closely at
the logic. I think most spots don't need discardable cleanups.
Tom
next prev parent reply other threads:[~2016-10-01 5:22 UTC|newest]
Thread overview: 123+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-27 4:49 [RFA 00/22] More C++-ification Tom Tromey
2016-09-27 4:41 ` [RFA 15/22] Use std::string in macho_symfile_read_all_oso Tom Tromey
2016-10-09 17:28 ` Pedro Alves
2016-10-10 22:40 ` Tom Tromey
2016-10-10 22:46 ` Pedro Alves
2016-09-27 4:41 ` [RFA 07/22] Change scoped_minimal_symbol_reader to store objfile Tom Tromey
2016-09-29 9:19 ` Trevor Saunders
2016-09-30 21:41 ` Tom Tromey
2016-09-27 4:42 ` [RFA 16/22] Use std::vector in elf_read_minimal_symbols Tom Tromey
2016-10-09 17:30 ` Pedro Alves
2016-09-27 4:42 ` [RFA 19/22] Convert tid_range_parser to class Tom Tromey
2016-09-30 1:41 ` Pedro Alves
2016-09-30 14:52 ` Tom Tromey
[not found] ` <926126cb-b3c5-340b-ac1c-5bc14ca41bf9@redhat.com>
2016-10-04 19:24 ` Pedro Alves
2016-10-04 23:09 ` Pedro Alves
2016-10-05 2:16 ` Trevor Saunders
2016-10-12 2:12 ` Tom Tromey
2016-10-13 1:06 ` Pedro Alves
2016-09-27 4:43 ` [RFA 20/22] Initial conversion of dwarf_expr_ctx Tom Tromey
2016-10-09 17:40 ` Pedro Alves
2016-09-27 4:45 ` [RFA 21/22] Convert DWARF expr functions to methods Tom Tromey
2016-10-09 19:18 ` Pedro Alves
2016-09-27 4:47 ` [RFA 22/22] Convert dwarf_expr_context_funcs " Tom Tromey
2016-10-09 19:11 ` Pedro Alves
2016-10-10 18:31 ` Pedro Alves
2016-10-10 19:33 ` Pedro Alves
2016-09-27 4:47 ` [RFA 05/22] Turn wchar iterator into a class Tom Tromey
2016-10-06 1:01 ` Pedro Alves
2016-09-27 4:47 ` [RFA 02/22] Use RAII to save and restore scalars Tom Tromey
2016-09-27 10:24 ` Trevor Saunders
2016-09-30 1:40 ` Pedro Alves
2016-09-30 9:22 ` Pedro Alves
2016-09-30 15:00 ` Tom Tromey
2016-09-30 23:50 ` Pedro Alves
2016-09-30 15:44 ` Tom Tromey
2016-09-30 23:51 ` Pedro Alves
2016-10-01 3:55 ` Tom Tromey
2016-10-01 4:23 ` Tom Tromey
2016-10-01 10:33 ` Pedro Alves
2016-10-02 17:11 ` Tom Tromey
2016-10-05 0:06 ` Pedro Alves
2016-10-12 22:36 ` Tom Tromey
2016-09-27 4:47 ` [RFA 04/22] Use scoped_restore for current_ui Tom Tromey
2016-09-27 4:48 ` [RFA 09/22] Remove make_cleanup_restore_current_ui Tom Tromey
2016-09-29 11:55 ` Trevor Saunders
2016-10-01 3:47 ` Tom Tromey
2016-10-01 4:29 ` Simon Marchi
2016-10-06 2:53 ` Tom Tromey
2016-10-06 1:24 ` Pedro Alves
2016-10-06 2:52 ` Tom Tromey
2016-10-09 4:31 ` Simon Marchi
2016-10-09 15:10 ` Tom Tromey
2016-10-09 19:20 ` Pedro Alves
2016-10-12 22:43 ` Tom Tromey
2016-10-13 1:28 ` Pedro Alves
2016-10-13 6:11 ` Eli Zaretskii
2016-10-13 10:16 ` Pedro Alves
2016-10-13 13:53 ` Eli Zaretskii
2016-10-13 14:26 ` Pedro Alves
2016-10-13 14:46 ` Eli Zaretskii
2016-10-13 15:04 ` Pedro Alves
2016-10-13 15:19 ` Eli Zaretskii
2016-10-13 15:43 ` Pedro Alves
2016-10-13 15:48 ` Pedro Alves
2016-10-17 23:43 ` Go C++11? (was: Re: [RFA 09/22] Remove make_cleanup_restore_current_ui) Pedro Alves
2016-10-18 6:14 ` Eli Zaretskii
2016-10-19 18:02 ` Go C++11? Luis Machado
2016-10-19 22:34 ` Pedro Alves
2016-10-13 15:27 ` [RFA 09/22] Remove make_cleanup_restore_current_ui Pedro Alves
2016-10-13 14:26 ` Trevor Saunders
2016-09-27 4:48 ` [RFA 01/22] Change selttest.c to use use std::vector Tom Tromey
2016-09-27 8:50 ` Trevor Saunders
2016-09-27 16:44 ` Tom Tromey
2016-09-28 14:58 ` Trevor Saunders
2016-09-29 8:59 ` Tom Tromey
2016-10-06 0:18 ` Pedro Alves
2016-10-06 0:39 ` Pedro Alves
2016-09-30 14:43 ` Simon Marchi
2016-09-30 21:40 ` Tom Tromey
2016-10-06 0:45 ` Pedro Alves
2016-09-27 4:48 ` [RFA 08/22] Record minimal symbols directly in reader Tom Tromey
2016-10-01 4:29 ` Simon Marchi
2016-10-06 1:12 ` Pedro Alves
2016-09-27 4:48 ` [RFA 03/22] Use scoped_restore for ui_file Tom Tromey
2016-10-01 4:28 ` Simon Marchi
2016-10-01 5:22 ` Tom Tromey [this message]
2016-10-01 11:47 ` Simon Marchi
2016-10-13 14:56 ` Tom Tromey
2016-09-27 4:50 ` [RFA 17/22] Remove make_cleanup_restore_current_uiout Tom Tromey
2016-09-29 14:35 ` Trevor Saunders
2016-09-29 15:23 ` Tom Tromey
2016-09-29 17:55 ` Simon Marchi
2016-09-29 20:34 ` Tom Tromey
2016-09-30 2:45 ` Pedro Alves
2016-09-30 23:48 ` Tom Tromey
2016-09-30 23:52 ` Pedro Alves
2016-09-27 4:51 ` [RFA 18/22] Some cleanup removal in dwarf2loc.c Tom Tromey
2016-10-09 17:37 ` Pedro Alves
2016-09-27 4:51 ` [RFA 13/22] Remove unnecessary cleanup from stabsread.c Tom Tromey
2016-09-30 16:19 ` Tom Tromey
2016-10-09 17:07 ` Pedro Alves
2016-09-27 4:51 ` [RFA 14/22] Replace two xmallocs with vector Tom Tromey
2016-10-09 17:20 ` Pedro Alves
2016-10-12 22:39 ` Tom Tromey
2016-10-13 1:17 ` Pedro Alves
2016-10-13 2:04 ` Tom Tromey
2016-10-13 15:15 ` Tom Tromey
2016-10-13 15:26 ` Trevor Saunders
2016-09-27 4:51 ` [RFA 12/22] Remove unnecessary null_cleanup Tom Tromey
2016-10-09 17:06 ` Pedro Alves
2016-09-27 4:52 ` [RFA 10/22] Remove some cleanups in MI Tom Tromey
2016-10-06 1:42 ` Pedro Alves
2016-09-27 4:52 ` [RFA 06/22] Introduce scoped_minimal_symbol_reader Tom Tromey
2016-10-06 1:10 ` Pedro Alves
2016-10-06 15:37 ` Tom Tromey
2016-10-10 23:06 ` Tom Tromey
2016-10-10 23:26 ` Pedro Alves
2016-09-27 8:32 ` [RFA 11/22] Change command stats reporting to use class Tom Tromey
2016-10-09 17:01 ` Pedro Alves
2016-10-11 17:31 ` Tom Tromey
2016-10-08 13:57 ` [RFA 00/22] More C++-ification Simon Marchi
2016-10-08 16:42 ` Pedro Alves
2016-10-09 2:09 ` Tom Tromey
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