[Ext] Re: [xsd-users] DLLs and --generate-element-type --generate-element-map

[Nicolas Weidmann]

Hello Boris,

I could give it a try yesterday and this morning.

Using both --export-xml-schema & --export-symbol worked as you expected.

However, with MSVC, I encountered the same issue I had with xsd::cxx::tree::string<C, B> regarding std::string being multiple-defined.

I then dropped --export-xml-schema & --export-symbol and added to my xml_schema epilogue:

template class XML_SCHEMA_EXPORT ::xsd::cxx::tree::element_map<char, ::xml_schema::Type>;

With this it works. I however had to add the following operators to my code as I am using a custom double:

void operator<<(xercesc::DOMElement& e, double d)
void operator<<(xercesc::DOMAttr& a, double d)
void operator<<(xml_schema::ListStream& ls, double d) // For in house conventions, I use --type-naming ucc --function-naming java

Are there other templates I MUST export other than ::xsd::cxx::tree::element_map<...> to have full type support with my base lib?

I noticed --export-maps, but didn't see any differences in the xml_schema header file generated.
But the documentation mentions: Export polymorphism support maps...

So, I should probably export other maps as well!?!

Another question, when using --generate-element-type --generate-element-map, I have to use element_map<...>::parse & serialize

Are there equivalent helpers to

::std::unique_ptr< :: my_namespace::MyElement >
  parseMyElement (::std::istream& is,
             ::xml_schema::Flags f = 0,
             const ::xml_schema::Properties& p = ::xml_schema::Properties ());

void serializeMyElement (::std::ostream& os,
                 const ::my_namespace::MyElement& x,
                 const ::xml_schema::NamespaceInfomap& m = ::xml_schema::NamespaceInfomap (),
                 const ::std::string& e = "UTF-8",
                 ::xml_schema::Flags f = 0);

For the moment I wrote template helper functions that do the work, but if something already exists, it would be much better for me to use it instead of my own helpers:

template<typename T>
std::unique_ptr<T> parse(std::istream& stream, xml_schema::Flags flags = 0, const xml_schema::Properties& properties = {})

void serialize(std::ostream& stream, const xml_schema::ElementType& element,
const xml_schema::NamespaceInfomap& infomap = {}, const char* encoding = nullptr, xml_schema::Flags flags = 0);

Regards,


Nicolas Weidmann
Banque Lombard Odier & Cie SA
Rue de la Corraterie 11 - 1204 Genève - Suisse
T +41 22 709 23 17
www.lombardodier.com
-----Original Message-----
From: Boris Kolpackov <boris at codesynthesis.com>
Sent: mardi, 30 juin 2026 16:11
To: Nicolas Weidmann <n.weidmann at lombardodier.com>
Cc: xsd-users at codesynthesis.com
Subject: [Ext] Re: [xsd-users] DLLs and --generate-element-type --generate-element-map

Nicolas Weidmann <n.weidmann at lombardodier.com> writes:

> I wanted to use --generate-element-type --generate-element-map in
> order to have a single parse & serialize as our code heavily relies
> on templates and parseMyType, etc. are not generic.
>
> It works fine as long as all the libs are static, but I need to have
> the different data-binding libraries to be DLLs.
>
> In that case, it fails as the different dlls have their own element
> map and the application code has its own, empty, element map.
>
> Do I have to implement my own --custom-type for the element map?

No, the overall approach is to have a "root" DLL that exports the
single map that everyone else imports. The element map is a class
template (with a static data member which is the actual map) and
exporting templates from DLLs is a murky business. If you want
to give it a go, the starting point would be to generate the
header for XML Schema built-in types (which includes the
element_map) and export it from your root DLL. Something along
these lines:

xsd cxx-tree \
  --generate-element-map \
  --generate-element-type \
  --export-xml-schema \
  --export-symbol XML_SCHEMA_EXPORT \
  --generate-xml-schema  \
  xml-schema.xsd

You would need to define XML_SCHEMA_EXPORT appropriately. You will also
need to have this header included in at least one source file that belongs
to the root DLL in order to have the template instantiations exported.

Once this is done, all your actual schemas would be compiled with
--extern-xml-schema in order to use this shared header.
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