Add File - Reload

[rhettinger]

BPO	1721083
Nosy	@rhettinger, @terryjreedy
Dependencies	bpo-1175686: add "reload" function to IDLE
Files	idle_filerevert.diff

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/terryjreedy'
closed_at = None
created_at = <Date 2007-05-18.02:15:52.000>
labels = ['expert-IDLE', 'type-feature', '3.10']
title = 'Add File - Reload'
updated_at = <Date 2020-07-28.00:56:04.086>
user = 'https://github.com/rhettinger'

bugs.python.org fields:

activity = <Date 2020-07-28.00:56:04.086>
actor = 'terry.reedy'
assignee = 'terry.reedy'
closed = False
closed_date = None
closer = None
components = ['IDLE']
creation = <Date 2007-05-18.02:15:52.000>
creator = 'rhettinger'
dependencies = ['1175686']
files = ['14635']
hgrepos = []
issue_num = 1721083
keywords = ['needs review']
message_count = 16.0
messages = ['55114', '55115', '55116', '55117', '59757', '59758', '70912', '91213', '91538', '112887', '186003', '186009', '186031', '371442', '374446', '374447']
nosy_count = 2.0
nosy_names = ['rhettinger', 'terry.reedy']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'test needed'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue1721083'
versions = ['Python 3.10']

[rhettinger]

When using CVS or SVN, it is common to revert or merge a file that is open in the editor. It would be great to have a reload/refresh option on the menu to bring in the changed file. Without that option, the only approach is to close without saving, fire-up the editor again, and reload the file manually.

[kbkaiser]

But isn't this an example of a bell/whistle which is outside IDLE's design policies? It would add a menu item which would be rather rarely used, especially by beginners, it seems to me. Why not just close the edit window (not IDLE) and re-open using the Files / Recent Files feature?

[taleinat]

I agree with KBK that what you suggest goes against IDLE's philosophy, which is to be simple and uncluttered, avoiding "bells and whistles".

However, I do think that a simple "revert file" menu item in the File menu, which would just reload the file from the file system, could be generally useful.

Additionally, IDLE could monitor the file on the file system, and if it is changed outside of IDLE, ask the user whether to continue with the current version or switch to the new version on disk. I've seen some text editors do this, and it can save some headaches. Drawbacks are that some users may find this annoying (at least at first), and it could be somewhat complex to implement. Thoughts on this? Perhaps this should be brought up on IDLE-dev?

Each of the above would allow you to revert/merge using whatever CVS/SVN/etc. tools you normally use, then just load the new version inside the already open instance of IDLE. I think this would be a good separation of roles between IDLE and version control tools.

[kbkaiser]

If you have more than one IDLE window open (even a shell), it's not necessary to shut down. Just close the edit window, confirm the unsaved warning, and use the Recent Files menu item to reopen with the current disk contents. We are talking about five mouse clicks instead of three, counting confirmation dialogs. In my opinion, it's not worth complicating IDLE and confusing beginners with a 'revert' menu item to save two clicks every other day or so.

I normally use IDLE with svn and never feel the need to reload something that was merged. After all, you should have updated before you opened the file in IDLE. If you modified the file in IDLE, saved, and checked it in, IDLE's copy is the same as svn.

Maybe you have a use case I haven't considered. If it's a good one, then a (normally inactive) IDLE extension might be warranted for those who really need this.

Adding a warning when saving that the file has changed on disk is a good emacs feature which has saved my bacon a number of times. That would be a good feature to add to IDLE, but that's a different request. Rejecting this one.

[Nashev]

It is very nice feature, that exists in many advanced and professional
GUI-based editors on the Windows and Mac. For example, i can fast name
TextWrangler, HomeSite, Flash, PhotoShop and it is only first names in
mind. It feature for simplify tool's usage, it is improve GUI usability.

[Nashev]

There are command in menu is called "Revert".

P.S.: for knowing that file changed, programs in windows can register OS
callback for this event and just react on it. In Mac i think too, but i
don't know how with it on unix and python.

[terryjreedy]

This appears to me to duplicate and supercede
http://bugs.python.org/issue1175686
If so, could that be closed as superceded?

[gpolo]

I have done a very initial patch in an attempt to define where we should
go with this feature. There are several different proposals around this
issue and the superseded one, I opted to implement the simplest one
which is to add a 'Revert' entry in the file menu which re-reads the
file currently open.

There are at least two problems with this patch. First, I don't think
there is a non-hacky way to place a command on a menu in a specific
place by using an idle extension, so, the 'Revert' entry is the last
entry in the file menu right now. I guess this would be solved by not
making this an extension and then proceed to manually remove the menu
entry while creating the shell window (similarly to what it is done when
running under mac osx). The second problem happens when reverting the
file, I'm not sure if it should be done differently but this seems to
cause some problem with Multicall.

[gpolo]

Kurt, there is now a patch on bpo-6699 which adds your suggested feature:

"Adding a warning when saving that the file has changed on disk is a
good emacs feature which has saved my bacon a number of times. That
would be a good feature to add to IDLE, but that's a different request".

[BreamoreBoy]

msg91213 states that there are two problems with the patch. Could we have comments from IDLE users please.

[rhettinger]

Roger, can you pick this one up?

Adding a "reload" option to the file menu benefits IDLE in two ways. First, it allows users to easily discard changes. Second, it helps IDLE play well with reverts and updates in version control systems. In the absence of this feature, users have to close their current file without saving and then re-open it from disk.

[terryjreedy]

Notepad++ has 'Reload from disk' right after New and Open, and I like that explicit wording. 'Revert' is a bit esoteric for beginners. (And I do not see that on the menu now.)

Kurt's argument applies to Notepad++ also -- one could close the file and reload from the recent files list, but there it is. There is a subtle psychological factor: reloading may mean 'I messed up and want to start over'. In that state, a simple direct reload is tension defuser.

Quite separately, Notepad++ check file modification times when it gets the focus and if the disk copy is newer, it pops up a box saying so and asking if one wants to reload. (Or perhaps it check for OS notifications at this time.) This is the feature directed at catching reverts and merges.

[serwy]

Raymond, I can pick this up. I might as well work on bpo-6699 at the same time.

[terryjreedy]

bpo-1175686 was not a dependency, but a duplicate closed in favor of this issue, because gpolo attached the diff here.

This is obviously not a high priority, but I still want to consider it. The addition would no longer be an extension, but likely a method in iomenu.

[terryjreedy]

All open files, up to the most recent 21 (and that could be increased) are in the recent file list. Clicking on any name loads that file, unless it is already loaded. The exception enforced in filelist.FileList.open, lines 29-32:

        if key in self.dict:
            edit = self.dict[key]
            edit.top.wakeup()
            return edit

I believe that we just need to ask, before the return, "Replace editor content with file content?" and if yes, call edit.io.loadfile(filename).

[terryjreedy]

Recent edits to iomenu.IOBinding.loadfile were intended to preserve the option of reloading a non-empty editor.