bug#20168: 25.0.50; (elisp) `Accessing Mouse', for `posn-object-x-y'

bug#20168: 25.0.50; (elisp) `Accessing Mouse', for `posn-object-x-y'

[Drew Adams]

The doc string is OK.  The manual is misleading/incorrect, in this
regard: it speaks about a case where "the POSITION is a buffer
position".  This is wrong, as a buffer position in Emacs means a natural
number 1,2... (or a marker).  Maybe what should be said in this case is
that "POSITION represents a buffer position".  Its value cannot be
simply a buffer position, which is a number or a marker.

In GNU Emacs 25.0.50.1 (i686-pc-mingw32)
 of 2014-10-20 on LEG570
Bzr revision: 118168 rgm@gnu.org-20141020195941-icp42t8ttcnud09g
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --enable-checking=yes,glyphs CPPFLAGS=-DGLYPH_DEBUG=1'

bug#20168: 25.0.50; (elisp) `Accessing Mouse', for `posn-object-x-y'

[Eli Zaretskii]

> Date: Sun, 22 Mar 2015 11:14:28 -0700 (PDT)
> From: Drew Adams <drew.adams@oracle.com>
> 
> The doc string is OK.  The manual is misleading/incorrect, in this
> regard: it speaks about a case where "the POSITION is a buffer
> position".  This is wrong, as a buffer position in Emacs means a natural
> number 1,2... (or a marker).

Why is it wrong?

> Maybe what should be said in this case is
> that "POSITION represents a buffer position".  Its value cannot be
> simply a buffer position, which is a number or a marker.

Why not?  And what's the difference between the current text and your
suggestion?

Or maybe you could provide an example where the docs are wrong.

bug#20168: 25.0.50; (elisp) `Accessing Mouse', for `posn-object-x-y'

[Drew Adams]

> > The doc string is OK.  The manual is misleading/incorrect, in this
> > regard: it speaks about a case where "the POSITION is a buffer
> > position".  This is wrong, as a buffer position in Emacs means a natural
> > number 1,2... (or a marker).
> 
> Why is it wrong?

It is wrong to say that the value is a buffer position, because a
buffer position is a number, not a position object (which is a cons).

> > Maybe what should be said in this case is
> > that "POSITION represents a buffer position".  Its value cannot be
> > simply a buffer position, which is a number or a marker.
> 
> Why not?  And what's the difference between the current text and your
> suggestion?

The difference is the difference between "is" and "represents".
The value *is* not a buffer position (which is a number).  It *is*
a position object (which is a cons).  It represents a buffer position
in this case.

It's a minor point, but it was enough to confuse me into trying
to pass an actual buffer position.  Nothing in the current
description says that POSITION must be a position object (i.e.,
something for which `posnp' returns non-nil).

bug#20168: 25.0.50; (elisp) `Accessing Mouse', for `posn-object-x-y'

[Eli Zaretskii]

> Date: Sun, 22 Mar 2015 11:47:28 -0700 (PDT)
> From: Drew Adams <drew.adams@oracle.com>
> Cc: 20168@debbugs.gnu.org
> 
> > > The doc string is OK.  The manual is misleading/incorrect, in this
> > > regard: it speaks about a case where "the POSITION is a buffer
> > > position".  This is wrong, as a buffer position in Emacs means a natural
> > > number 1,2... (or a marker).
> > 
> > Why is it wrong?
> 
> It is wrong to say that the value is a buffer position, because a
> buffer position is a number, not a position object (which is a cons).
> 
> > > Maybe what should be said in this case is
> > > that "POSITION represents a buffer position".  Its value cannot be
> > > simply a buffer position, which is a number or a marker.
> > 
> > Why not?  And what's the difference between the current text and your
> > suggestion?
> 
> The difference is the difference between "is" and "represents".
> The value *is* not a buffer position (which is a number).  It *is*
> a position object (which is a cons).  It represents a buffer position
> in this case.
> 
> It's a minor point, but it was enough to confuse me into trying
> to pass an actual buffer position.  Nothing in the current
> description says that POSITION must be a position object (i.e.,
> something for which `posnp' returns non-nil).

OK, fixed.  Thanks.