RE: generate 1) virtual index

[Drew Adams]

> Below is a simple patch that implements this:

Good. [I typed "forward" as the input regexp.]

I realize this was a first try, and here is some feedback. Compared to a
normal Index page such as Concept Index, I see these formatting differences
(drawbacks):

1. It says `File: apropos' instead of `File: emacs' (for the Emacs manual).
`File:' should point to the manual being indexed.

2. `Node: Index' is not quite correct. It would be better to use `Node:
Index for `forward'', where `forward' is the regexp input by the user, which
defines this particular virtual index. [BTW, `Node' for `L' says `Top',
which is not correct either (it should be something like `History').]
Together, `File:' and `Node:' would then uniquely identify a virtual index
(node).

3. The `Up:' link is `(dir)'. It should be `Top', to send you to the top of
the manual that is being indexed.

4. The description "Nodes whose indices contain `forward':" should come
before, not after, `* Menu:'.

5. That description should say "Index entries that match `forward':". (a) It
is the index entries that match, not the whole indexes. (b) It is the index
entries that are listed (the nodes are also listed, but the index entries
are primary). (c) It is regexp matching that is used, not necessarily
substring containment, IIUC.

Actually, I think you could dispense with the description line altogether,
if the `Node:' name is descriptive, as suggested in #2: `Node: Index for
`forward''.

6. Each menu item should be formatted as in a normal index: (a) no file name
written next to either the index entry or the node name, (b) alignment using
tabs, not a space. IOW, use this:

 * search-forward:              Nonincremental Search.

not this, which is what I see:

 * search-forward [c:/Emacs-22.1/info/emacs]:
(c:/Emacs-22.1/info/emacs)Nonincremental Search.


#3 and #6 make me think that you are perhaps intending this for use across
multiple books. Is that right?

Such a feature might be useful, but if it exists it should have a different
command name and a different binding. When used within a manual, `I' should
produce a virtual index for only that manual. In this case, I hit `I' in the
Emacs manual, so only the Emacs manual should be used for this virtual
index.

But if `I' is hit in `(dir)', then you could fall back to the multi-book
command, which would ask which books to use. If multiple manuals are used,
then you could include the Info file indication in the menu items, but it
should be listed only once, next to the node name, not the index entry, and
it should use the standard Info file format, e.g. `(emacs)', not an absolute
file name.

Question: Once such a virtual node has been created, couldn't it be
referenced in the history? `l' and `r' do access it properly, but it does
not seem to get registered with `L'. It's important that `L' be able to
access all visited nodes, including such virtual nodes.

HTH, and thanks; this is useful.