This patch substitutes by isAttachedToDocument() (almost) everywhere where
getNameInDocument() is used for this purpose.
The very few places not touched by this patch demand a (just a little) less trivial change.
When we change the returning type of getNameInDocument() to std::string,
those places will be easily found, because they shall generate a compiler error
(converting std::string to bool).
Rationale:
The fact that getNameInDocument() return nullptr to indicate
that the object is not attached to a document is responsible for lots of bugs
where the developer does not check for "nullptr".
The idea is to eliminate all those uses of getNameInDocument() and, in the near future,
make getNameInDocument() return always a valid std::string.
Cell binding allows one to bind a range of cells of one sheet to another
range of cells of an arbitary sheet, including any empty cells in the
range.
The binding is implemented with PropertyExpressionEngine and
PropertySheet::setPathValue(), which binds a special path of
PropertySheet, such as
.cells.Bind.A1.D1
to an expression, such as
tuple(.cells, <<A2>>, <<A5>>)
The A1 and D1 in the example above specifies the binding start and end
cell address. And <<A2>> and <<A5>> are the range of cells to bind to.
Note that you can use any expression that evalutes to string for the
binding destination, e.g. <<A%d>> % B1, which uses the value inside B1
to construct the binding destination. The '.cells' in the tuple shown
above is an example to bind cells of the same PropertySheet. It can be
change to to reference to any other spreadsheet, even those outside the
current document, e.g. Document#Spreadsheet001.cells
Any object reference inside this function is treated as hidden to
exclude it from dependency calculation. This function allows some form
of cyclic depdenency.
Merger note: renamed from "HREF" to "HIDDENREF" to avoid confusion with
the standard "hypertext reference" use of HREF.
* Support sub-object reference syntax using the following syntax,
Part.<<Box.>>.Placement
or, with sub-object label referencing
Part.<<$Cube.>>.Placement
* Extend indexing support, including range based indexing, e.g.
A1[B2+1][C3][D4:-1]
* Add new constants, None, True, true, False, false.
