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.
To compare if two property contains the same content. The default
implementation in Property uses the persistense interface to save both
properties to string and compares the content. This may not work at the
moment if the property saves content in separate file or in binary.
Various properties have cheaper implementation to direct compare their
internal values.
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.
The problem happens when partial loading is enabled. If document A
contains a link to some object in document B, it will load B as partial
document with only that object and its necessary dependencies. But if
document A contains another link to some object in document C which also
has a link to some object in document B, the link in document C may not
be restored, because document B is partially loaded without the linked
object. This patch will check for this case and reload document B for
more objects.
See an example reported in
https://forum.freecadweb.org/viewtopic.php?p=495078#p495078
