[eclipse-dev] Changing the default line separator for text files.

[Mike Wilson <Mike_Wilson@xxxxxxxxxx>]

Bug 3970 is one of the oldest (so old that it actually predates our use of 
bugzilla) and most highly voted on (74 votes, 39 people on the CC list) 
open feature requests. Over the years, we have done a significant number 
of things to address issues related to line separators, but we never 
actually added the feature that this bug describes; that is, a simple way 
to specify what line separator character will be used when new text files 
are created.

For Eclipse R3.1, we will (finally) be addressing this by providing both 
the necessary plumbing (preferences, GUI to set them, etc.) and associated 
support in the SDK text file creation code. I encourage all developers 
whose plug-ins create text files to take a look at
    https://bugs.eclipse.org/bugs/show_bug.cgi?id=3970
and the dependent bugs, and consider whether they should be using the new 
support to allow new text files to be created with line separators that 
differ from the platform ones (e.g. to use Linux ("\n") separators on 
Windows ("\r\n") platforms).

IMPORTANT: This is not a breaking change. Existing code that creates text 
files, but which does not make use of the new support, will continue to 
work as it always has. Typically, this means that the platform line 
separator will be used, but this is (still) at the discretion of the 
plug-in.

For added context, here is an excerpt from bug 3970 (see the bug for 
more)....

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In the current Eclipse R3.1 development builds the following support for 
custom line separators already exists [yes, you probably know this 
already]:

1) When opened on an existing text file that contains line separators, the 
standard Eclipse editors detect which line separator the file uses, and 
continue to use that one as new lines are added. This should prevent 
"mixed" line separators from appearing in files.

2) The CVS repository provider (i.e. the Eclipse code we wrote to talk to 
CVS) has a preference checkbox "Convert text files to use platform line 
ending", which can be found in the "Files and Folders" tab of the "CVS" 
preference page (under the "Team" preference page). By default this 
preference is checked, but if you *uncheck* it, CVS will not modify the 
line separators of text files when they are checked out of (or into) CVS. 
This, together with point 1), should allow a team with developers working 
on multiple platforms to work with existing text files without causing the 
line separator to be modified.

3) As Dani mentioned above, the "File" > "Convert Line Delimiters To" menu 
operation can now be applied to whatever is selected, be they files, 
folders or projects. This should allow wholesale conversion of existing 
text files without grief.

Honestly, I think this already a pretty good story, but none of it 
actually addresses the feature requested by this bug: "UI needed to define 
the default line delimiters for new files". So here's what we're going to 
do:

1) We'll provide a per-project preference that allows you to choose what 
you want the default line separator to be for new text files created in 
that project. By putting it on the project, the value will be shared with 
the project. This, together with the features described above, lets a team 
of developers working on the shame project always use a particular line 
separator both when editing existing files and creating new ones.

2) We'll provide the same kind of preference for the workspace as a whole. 
This will be used for projects that do not explicitly have the preference 
set. Note that, if you want the line separator setting to "stick" to your 
work, you will want to use the project setting rather than this one 
(because even if you weren't sharing the project, you would have to 
remember re-set it every time you got a new workspace).

3) We'll modify the standard places where text files are created to detect 
and use these properties. One *very* important thing to keep in mind about 
this is that, we don't have control over all of the text file creating 
tools that have been written by the Eclipse community. Some of these, by 
nature of how they fit into the underlying frameworks, may do the right 
thing with the new preferences, some probably won't. I presume you will 
take on the task of evangelizing the need to support this new capability 
with the authors of the plugins you care about. ;-)

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You should see these changes showing up in current nightly builds. The GUI 
for setting the preferences can be found in the Project > Properties > 
Info page and the Window > Preferences > General > Editors page.

McQ.