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| '''This extension is in proposal stage.''' | '''This extension is not distributed with Mercurial.''' |
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| Download site: [http://files.movedbylight.com/cgi-bin/hg/hgfold/] | Download site: [[http://files.movedbylight.com/cgi-bin/hg/hgfold/]] |
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| === Jargon === | Works with: Mercurial 1.2.1 (and probably beyond, but not tested with later versions yet). === Definitions === |
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| It's developed with these core principles (open for community discussion, cf. CaseFolding): | Basic understandings about filename collisions. |
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| A couple big questions: | === Mercurial Command Extension === |
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| 1. Is coercing case to manifest ever the right thing? What if your software is trying to rename a file to some cannonical case as a correction to application or user sloppiness? 1. CI merging two heads could result in more than a three-way merge this extension hasn't been used consistently on all copies. For instance, You even on a Windows machine you could end up with two heads that each have files "Apple" and "apple". That's a five-way merge. And finding a common ancestor gets really strange. What if Apple-1, Apple-2, and apple-1 share an ancestor, but apple-2 was added independently. The best thing would be some core declaration upon ''hg init'' declaring a repo to be CI for all adds, commits, and merges. But until then, we're effectively telling Mercurial, "You know that thing you didn't think was a conflict? Well, it is. So merge it." |
This extension demonstrates a way of extending existing mercurial commands (as opposed to simply adding a new command). There are risks and advantages to this. It tries to do it as safely as possible: 1. The original command entry if found and retained. 1. New options are audited so they will not overlap with existing command options (even future ones). 1. Command help and syntax is augmented. 1. A wrapper function is called instead of the original command function. Best practice is for that wrapper, if it learns that its extra services are not needed, to execute the original command function with the arguments pertinent to it. === Other Types of Filename Collisions === This extension acknowledges that there are other ways for filenames to collid besides case. By changing the definition of collisionFinder.cannonize(), it can be taught to find other types of filename collisions. I welcome any suggestions. |
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| Other approaches are outlined at CaseFolding. |
Fold: Case Folding Rescue
This extension is not distributed with Mercurial.
Author: BradOlson
Download site: http://files.movedbylight.com/cgi-bin/hg/hgfold/
Works with: Mercurial 1.2.1 (and probably beyond, but not tested with later versions yet).
Definitions
- FS
- Filesystem (file system).
- CS
- Case-sensitive (case-preserving), a context where "THEGREENTREE" and "thegreentree" refer to two different files.
- CI
- Case-insensitive (case-folding), a context where "THEGREENTREE" and "thegreentree" refer to the same file or entity.
- Collision
- Case collision, two names that differ only by case.
Overview
This extension seeks to comprehensively deal with the problem of Mercurial filename case collisions in merges and updates. (It does not address Mercurial's internal storage, which is and needs to be CI no matter the file system, cf. CaseFoldingPlan.)
Basic understandings about filename collisions.
- It takes a person to decide whether a project's filenames are CI or CS. Current FS is not an adequate decider.
- In a CS project, a collision is just another file; in a CI project, a collision is a conflict.
Mercurial users need sane ways to remedy collisions on a CIFS. (It's easy to fix them on a CSFS, but on a CIFS you have to modify parentage, which can get dangerous. See FixingCaseCollisions.)
It proposes the following phases:
(Done) Add options to merge and update that will treat collisions as conflicts that need merging.
Adding options to other commands (add, addrem, commit, clone, and rename) to handle/prevent folds.
- Add .hgfold to define cannonical forms of filenames and flag that a repository needs to behave as if file names case-insensitive
Limitations
This extension has not been tested on filenames containing characters outside the basic Roman set.
Configuration
Configure your .hgrc to enable the extension by adding following lines:
[extensions] fold = /full/path/to/fold.py
Usage
hg help update and hg help merge have been augmented to describe this extension.
hg update --fold [-C] [-d DATE] [[-r] REV]
-n --dry-run do not perform actions, just print output
--fold treat filename collisions as the same file, merging as needed
hg merge --fold [-f] [[-r] REV]
-n --dry-run do not perform actions, just print output
--fold treat filename collisions as the same file, merging as needed
Development Discussion
Mercurial Command Extension
This extension demonstrates a way of extending existing mercurial commands (as opposed to simply adding a new command). There are risks and advantages to this. It tries to do it as safely as possible:
- The original command entry if found and retained.
- New options are audited so they will not overlap with existing command options (even future ones).
- Command help and syntax is augmented.
- A wrapper function is called instead of the original command function. Best practice is for that wrapper, if it learns that its extra services are not needed, to execute the original command function with the arguments pertinent to it.
=== Other Types of Filename Collisions ===
This extension acknowledges that there are other ways for filenames to collid besides case. By changing the definition of collisionFinder.cannonize(), it can be taught to find other types of filename collisions.
I welcome any suggestions.
Other Solutions
Other approaches are outlined at CaseFolding.