6.2. Creating a Library¶
-6.2.1. Using Autotools¶
-It is possible to use Autotools to create a library written in Vala. A library is created by using C code generated by Vala compiler, linked and installed as any other library. Then you need tell which C files must be used to create the library and which of them must be distributable, allowing others to compile a tarball without Vala using standard Autotools commands: configure, make and make install.
-6.2.1.1. Example¶
-This example was taken from GXml recent additions. GXmlDom is a library aimed to have a GObject based libxml2 replacement; is written in Vala and originally used to use WAF to build.
--
-
valac can be used to generate C code and headers from Vala sources. At this time is possible to generate a GObjectIntrospection and the VAPI file from the vala sources too.
-gxml.vala.stamp is used as the code sources for our library.
-
It’s important to add –pkg switches in order to valac to success and set all CFLAGS and LIBS required by the C library to compile and link against.
-NULL =
-
-
-AM_CPPFLAGS = \
- -DPACKAGE_LOCALE_DIR=\""$(prefix)/$(DATADIRNAME)/locale"\" \
- -DPACKAGE_SRC_DIR=\""$(srcdir)"\" \
- -DPACKAGE_DATA_DIR=\""$(datadir)"\"
-
-BUILT_SOURCES = gxml.vala.stamp
-CLEANFILES = gxml.vala.stamp
-
-AM_CFLAGS =\
- -Wall\
- -g \
- $(GLIB_CFLAGS) \
- $(LIBXML_CFLAGS) \
- $(GIO_CFLAGS) \
- $(GEE_CFLAGS) \
- $(VALA_CFLAGS) \
- $(NULL)
-
-lib_LTLIBRARIES = libgxml.la
-
-VALAFLAGS = \
- $(top_srcdir)/vapi/config.vapi \
- --vapidir=$(top_srcdir)/vapi \
- --pkg libxml-2.0 \
- --pkg gee-1.0 \
- --pkg gobject-2.0 \
- --pkg gio-2.0 \
- $(NULL)
-
-libgxml_la_VALASOURCES = \
- Attr.vala \
- BackedNode.vala \
- CDATASection.vala \
- CharacterData.vala \
- Comment.vala \
- Document.vala \
- DocumentFragment.vala \
- DocumentType.vala \
- DomError.vala \
- Element.vala \
- Entity.vala \
- EntityReference.vala \
- Implementation.vala \
- NamespaceAttr.vala \
- NodeList.vala \
- NodeType.vala \
- Notation.vala \
- ProcessingInstruction.vala \
- Text.vala \
- XNode.vala \
- $(NULL)
-
-libgxml_la_SOURCES = \
- gxml.vala.stamp \
- $(libgxml_la_VALASOURCES:.vala=.c) \
- $(NULL)
-
-# Generate C code and headers, including GObject Introspection GIR files and VAPI file
-gxml-1.0.vapi gxml.vala.stamp GXml-1.0.gir: $(libgxml_la_VALASOURCES)
- $(VALA_COMPILER) $(VALAFLAGS) -C -H $(top_builddir)/gxml/gxml-dom.h --gir=GXmlDom-1.0.gir --library gxmldom-1.0 $^
- @touch $@
-
-
-# Library configuration
-libgxml_la_LDFLAGS =
-
-libgxml_la_LIBADD = \
- $(GLIB_LIBS) \
- $(LIBXML_LIBS) \
- $(GIO_LIBS) \
- $(GEE_LIBS) \
- $(VALA_LIBS) \
- $(NULL)
-
-include_HEADERS = \
- gxml.h \
- $(NULL)
-
-pkgconfigdir = $(libdir)/pkgconfig
-pkgconfig_DATA = libgxml-1.0.pc
-
-gxmlincludedir=$(includedir)/libgxml-1.0/gxml
-gxmlinclude_HEADERS= gxml-dom.h
-
-# GObject Introspection
-
-if ENABLE_GI_SYSTEM_INSTALL
-girdir = $(INTROSPECTION_GIRDIR)
-typelibsdir = $(INTROSPECTION_TYPELIBDIR)
-else
-girdir = $(datadir)/gir-1.0
-typelibsdir = $(libdir)/girepository-1.0
-endif
-
-# GIR files are generated automatically by Valac so is not necessary to scan source code to generate it
-INTROSPECTION_GIRS =
-INTROSPECTION_GIRS += GXmlDom-1.0.gir
-INTROSPECTION_COMPILER_ARGS = \
- --includedir=. \
- --includedir=$(top_builddir)/gxml
-
-GXmlDom-1.0.typelib: $(INTROSPECTION_GIRS)
- $(INTROSPECTION_COMPILER) $(INTROSPECTION_COMPILER_ARGS) $< -o $@
-
-gir_DATA = $(INTROSPECTION_GIRS)
-typelibs_DATA = GXmlDom-1.0.typelib
-
-vapidir = $(VALA_VAPIDIR)
-vapi_DATA=gxmldom-1.0.vapi
-
-CLEANFILES += $(INTROSPECTION_GIRS) $(typelibs_DATA) gxml-1.0.vapi
-
-EXTRA_DIST = \
- libgxml-1.0.pc.in \
- $(libgxml_la_VALASOURCES) \
- $(typelibs_DATA) \
- $(INTROSPECTION_GIRS) \
- gxml.vala.stamp
-6.2.2. Compilation and linking using Command Line¶
+6.2.1. Compilation and linking using Command Line¶
Vala is not yet capable of directly creating dynamic or static libraries. To create a library, proceed with the -c (compile only) switch and link the object files with your favourite linker, i.e. libtool or ar.
$ valac -c ...(source files)
$ ar cx ...(object files)
or by compiling the intermediate C code with gcc
+or by compiling the intermediate C code in the compiler of you choice. We’ll be using gcc in these examples.
$ valac -C ...(source files)
$ gcc -o my-best-library.so --shared -fPIC ...(compiled C code files)...
6.2.2.1. Example¶
+6.2.1.1. Example¶
The following is an example of how to write a simple library in Vala, and also to compile and test it locally without having to install it first.
Save the following code to a file test.vala. This is the actual library code, containing the functions we want to call from our main program.
GIR files are XML descriptions of the API.
+This will generate a GIR file named Test-1.0.gir. The name of the GIR file should follow the GObject Introspection
+naming conventions and include an API version number.
A typelib file can then be generated from the GIR using g-ir-compiler:
+g-ir-compiler --output MyLibrary-1.0.typelib MyLibrary-1.0.gir
+GIR files are typically used to generate compile time bindings.
+Typelib files are used to create runtime bindings and a binding generator
+will read them using libgirepository.