saving buffer with text properties

saving buffer with text properties

[Drew Adams]

Is there any plan to enable users to save text with all of its properties?

The Emacs manual says that `invisible' and `intangible' are not saved. It
would be useful to be able to save a file and, upon reopening, restore all
of the Emacs text properties, including properties that are not predefined.

For instance, I have a library that implements conditional text, as in a
desktop publishing system such as Framemaker: easily hide/show arbitrary
sets of faces in regions etc. However, upon saving, all of this info is
lost.

Re: saving buffer with text properties

[Thien-Thi Nguyen]

() "Drew Adams" <drew.adams@oracle.com>
() Sat, 2 Jun 2007 19:33:56 -0700

   Is there any plan to enable users to save text
   with all of its properties?

"all" is a big word!

on the trunk, see (info "(elisp) Format Conversion").

perhaps if/when you write code to handle your specific
properties, we can look at their generality and extend
emacs w/ that functionality.

thi

RE: saving buffer with text properties

[Drew Adams]

>    Is there any plan to enable users to save text
>    with all of its properties?
>
> "all" is a big word!

Perhaps. If a text property were represented in the saved form by its
property name as well as its value, why couldn't arbitrary, user-defined
properties be accomodated too? That's a question, not a claim; I'm no expert
in this. (`buffer-invisiblity-spec' would also need to be saved in the
file.)

> on the trunk, see (info "(elisp) Format Conversion").

Good to know. IIUC, that explains how one might implement what I'm asking
for, and it is not specific to text properties. I was wondering if there was
already a plan to define a saved representation that would take text
properties into account - similar to (or perhaps an extension of) enriched
text, for instance.

> perhaps if/when you write code to handle your specific
> properties, we can look at their generality and extend
> emacs w/ that functionality.

My code just uses:

* a `face' property
* a `highlight' property with the same value as `face'
* possibly an `invisible' property

(Likewise for overlays, with a priority also, but I'm thinking only about
text properties here.)

The `highlight' property is just so the code can distinguish face properties
that it manages from other face properties. The code doesn't do anything
special. It just lets you easily apply highlighting in different faces and
then show/hide it.

User can already do some of these things from the Special Properties menu of
Text Properties; my code just tries to add a little flexibility, letting you
show/hide a given face or set of faces everywhere, in a region, etc.

The code is here: http://www.emacswiki.org/cgi-bin/wiki/highlight.el.

Re: saving buffer with text properties

[Chong Yidong]

"Drew Adams" <drew.adams@oracle.com> writes:

>>    Is there any plan to enable users to save text
>>    with all of its properties?
>>
>> "all" is a big word!

I think the way to do this is to build hooks into the desktop.el
system, so that external packages can specify a list of text
properties to re-apply to each file when it is re-opened.  This
information would be saved in .emacs.d, and the cache can be cleared
out for files that have not been re-opened for N days.

RE: saving buffer with text properties

[Drew Adams]

> >>    Is there any plan to enable users to save text
> >>    with all of its properties?
> >>
> >> "all" is a big word!
>
> I think the way to do this is to build hooks into the desktop.el
> system, so that external packages can specify a list of text
> properties to re-apply to each file when it is re-opened.  This
> information would be saved in .emacs.d, and the cache can be cleared
> out for files that have not been re-opened for N days.

But the per-file information about applied text properties needs to be saved
with the file, no? The problem is not just re-applying properties;
currently, they are not saved in any way AFAICT.

Or did you mean that desktop would save a list of files and their text
properties (including property values and locations)?

Re: saving buffer with text properties

[Thien-Thi Nguyen]

() "Drew Adams" <drew.adams@oracle.com>
() Sun, 3 Jun 2007 07:15:54 -0700

   If a text property were represented in the saved form by its property
   name as well as its value, why couldn't arbitrary, user-defined
   properties be accomodated too? That's a question, not a claim; I'm no
   expert in this. (`buffer-invisiblity-spec' would also need to be
   saved in the file.)

everything can be accomodated in the current situation (w/ a SMOP).  the
question is not of feasability, it is of design.  consider the property
name: under sane usage it is a symbol or a keyword, but guess what,
emacs has no qualms w/ `(put-text-property 1 2 "foo" "bar")'.  what if
the property name is a circular structure?, a hash?, something tricky to
serialize?  same question goes for the property value, of course.

when serialization is required, ordering comes into play.  ordering
implies priority and thus specific design for specific purposes.  all
the mechanisms to support ordering are in place, hence the pointer:

   > on the trunk, see (info "(elisp) Format Conversion").

   Good to know. IIUC, that explains how one might implement what I'm
   asking for, and it is not specific to text properties.

you are right, but that is irrelevant.  text properties are key/value
object pairs; format conversion is parsing/rendering of such pairs (as
well as other kinds of info) serially, given an ordering.

   I was wondering if there was already a plan to define a saved
   representation that would take text properties into account - similar
   to (or perhaps an extension of) enriched text, for instance.

you are (again) invited to design, codify and characterize a good plan.
probably a first step is to restrict the types of the text property name
and value to avoid the hair mentioned above.  you have already begun:

   My code just uses:

   * a `face' property
   * a `highlight' property with the same value as `face'
   * possibly an `invisible' property

your design should also handle properties your code does NOT use.

thi

Re: saving buffer with text properties

[Chong Yidong]

"Drew Adams" <drew.adams@oracle.com> writes:

>> >>    Is there any plan to enable users to save text
>> >>    with all of its properties?
>> >>
>> >> "all" is a big word!
>>
>> I think the way to do this is to build hooks into the desktop.el
>> system, so that external packages can specify a list of text
>> properties to re-apply to each file when it is re-opened.  This
>> information would be saved in .emacs.d, and the cache can be cleared
>> out for files that have not been re-opened for N days.
>
> But the per-file information about applied text properties needs to be saved
> with the file, no?

That would interfere with third-party programs, such as other text
editors, that want to edit the file.

> Or did you mean that desktop would save a list of files and their text
> properties (including property values and locations)?

Basically.  Desktop should provide hooks that other packages (such as
major modes) can use, i.e. a major mode should be able to tell desktop
"save the following data when closing this file, then run this
function with that data when the file is reopened".

RE: saving buffer with text properties

[Drew Adams]

> you are (again) invited to design, codify and characterize a good plan.
> probably a first step is to restrict the types of the text property name
> and value to avoid the hair mentioned above.  you have already begun:
...
> your design should also handle properties your code does NOT use.

I do appreciate the info you provided, Thi. I don't really intend to design
or implement such a thing myself, however. I don't have the resources or the
expertise to do that. I'm not averse to learning, of course, but I don't
expect to focus on that.

I was just asking if there were perhaps already plans afoot to do something
like this (I take it that the answer is no). I don't foreswear contributing
questions or comments to a discussion, if some such initiative develops, but
I don't intend to be a big part of it.

RE: saving buffer with text properties

[Drew Adams]

> > But the per-file information about applied text properties
> > needs to be saved with the file, no?
>
> That would interfere with third-party programs, such as other text
> editors, that want to edit the file.

Perhaps you're right about that. I don't know much about this stuff. We
already provide metadata in the form of local-variable declarations in
comments, but I recognize that this should also be applicable to files that
aren't necessarily code and don't necessarily have a comment syntax.
(Besides, trying to record this stuff in comments would likely be a
nightmare, if not also problematic.)

> > Or did you mean that desktop would save a list of files and their text
> > properties (including property values and locations)?
>
> Basically.  Desktop should provide hooks that other packages (such as
> major modes) can use, i.e. a major mode should be able to tell desktop
> "save the following data when closing this file, then run this
> function with that data when the file is reopened".

That sounds reasonable to me, from the little I know of this. As I mentioned
to Thi, this is not something that I expect to work on, so I'll generally
bow out of trying to design and implement this. I was really just trying to
find out if something already existed, or was planned, which I might be able
to take advantage of for my highlighting code.

Re: saving buffer with text properties

[Richard Stallman]

    Is there any plan to enable users to save text with all of its properties?

The plan for how to do this is to use the format conversion feature as
a basis, and implement conversion to and from existing formats that
can record markup.  We could also invent our own new format, but that
would be less useful than interoperation with other programs.

One existing format we want to support is RTF.  Would RTF do this job?

I don't think this should be connected with desktop.el.
That is not a clean design.  desktop.el has a job to do,
and that includes revisiting files that you were looking at.
Making saving and visiting handle text properties is a different job
and the two should be kept independent.

RE: saving buffer with text properties

[Drew Adams]

>     Is there any plan to enable users to save text with all of
>     its properties?
>
> The plan for how to do this is to use the format conversion feature as
> a basis, and implement conversion to and from existing formats that
> can record markup.  We could also invent our own new format, but that
> would be less useful than interoperation with other programs.
>
> One existing format we want to support is RTF.  Would RTF do this job?

I don't know. Would it allow for user-defined text properties? invisible?
intangible?

> I don't think this should be connected with desktop.el.
> That is not a clean design.  desktop.el has a job to do,
> and that includes revisiting files that you were looking at.
> Making saving and visiting handle text properties is a different job
> and the two should be kept independent.

That makes sense to me.

Re: saving buffer with text properties

[Richard Stallman]

    > One existing format we want to support is RTF.  Would RTF do this job?

    I don't know. Would it allow for user-defined text properties? invisible?
    intangible?

I do not know much about RTF.  I can't tell you.

Re: saving buffer with text properties

[Jason Rumney]

Richard Stallman wrote:
> I don't think this should be connected with desktop.el.
>   

There's enriched.el, it mentions support for other formats like RTF and
HTML in its TODO list (currently it uses a format defined for MIME mail,
which is little used these days).

Re: saving buffer with text properties

[M Jared Finder]

Richard Stallman wrote:
>     > One existing format we want to support is RTF.  Would RTF do this job?
> 
>     I don't know. Would it allow for user-defined text properties? invisible?
>     intangible?
> 
> I do not know much about RTF.  I can't tell you.

A suggestion from an Emacs user, not a developer.... YOU HAVE BEEN WARNED!

How about using HTML?  You could save user defined symbol properties as 
HTML <emacs-symbol> tags, and they'd end up ignored by web browsers, 
while common tags like <b> and <i> would work just fine.

   -- MJF

Re: saving buffer with text properties

[Richard Stallman]

    How about using HTML?  You could save user defined symbol properties as 
    HTML <emacs-symbol> tags, and they'd end up ignored by web browsers, 
    while common tags like <b> and <i> would work just fine.

It would be good to support saving as HTML too.
We just need someone to implement it.

Re: saving buffer with text properties

[Richard Stallman]

    There's enriched.el, it mentions support for other formats like RTF and
    HTML in its TODO list (currently it uses a format defined for MIME mail,
    which is little used these days).

enriched.el is the basic mechanism on which support for RTF
or HTML would be based.

Re: saving buffer with text properties

[Michael Olson]

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"Drew Adams" <drew.adams@oracle.com> writes:

> Is there any plan to enable users to save text with all of its properties?
>
> The Emacs manual says that `invisible' and `intangible' are not saved. It
> would be useful to be able to save a file and, upon reopening, restore all
> of the Emacs text properties, including properties that are not predefined.
>
> For instance, I have a library that implements conditional text, as in a
> desktop publishing system such as Framemaker: easily hide/show arbitrary
> sets of faces in regions etc. However, upon saving, all of this info is
> lost.

This would be something best handled by format.el.

At some point I plan to extend format.el (as requested by RMS in October
2006) to handle overlapping text properties, and then switch muse-mode
over to it.

-- 
       Michael Olson -- FSF Associate Member #652     |
 http://mwolson.org/ -- Jabber: mwolson_at_hcoop.net  |  /` |\ | | |
            Sysadmin -- Hobbies: Lisp, GP2X, HCoop    | |_] | \| |_|
Projects: Emacs, Muse, ERC, EMMS, ErBot, DVC, Planner |

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