Using the Generator¶

When the Djinni file(s) are ready, from the command line you can run:

djinni \
   --java-out JAVA_OUTPUT_FOLDER \
   --java-package com.example.jnigenpackage \
   --java-cpp-exception DbxException \ # Choose between a customized C++ exception in Java and java.lang.RuntimeException (the default).
   --ident-java-field mFooBar \ # Optional, this adds an "m" in front of Java field names
   \
   --cpp-out CPP_OUTPUT_FOLDER \
   \
   --jni-out JNI_OUTPUT_FOLDER \
   --ident-jni-class NativeFooBar \ # This adds a "Native" prefix to JNI class
   --ident-jni-file NativeFooBar \ # This adds a prefix to the JNI filenames otherwise the cpp and jni filenames are the same.
   \
   --objc-out OBJC_OUTPUT_FOLDER \
   --objc-type-prefix DB \ # Apple suggests Objective-C classes have a prefix for each defined type.
   \
   --objcpp-out OBJC_OUTPUT_FOLDER \
   \
   --py-out PYTHON_OUTPUT_FOLDER \
   --pycffi-out CFFI_OUTPUT_FOLDER \ # Required for Python support
   --pycffi-package-name PyCFFIlib \
   --pycffi-dynamic-lib-list mylib \
   --c-wrapper-out C_WRAPPER_OUTPUT_FOLDER \ # Required for Python support
   \
   --idl MY_PROJECT.djinni

Note

If a language's output folder is not specified, that language will not be generated.

All Arguments¶

General¶

Argument	Description
`--help`	Print help
`--version`	Print version
`--idl <in-file>`	The IDL file with the type definitions, typically with extension `.djinni`.
`--idl-include-path <path> ...`	An include path to search for Djinni `@import` and `@extern` directives. Can specify multiple paths.

Java¶

Argument	Description
`--java-out <out-folder>`	The output for the Java files (Generator disabled if unspecified).
`--java-package ...`	The package name to use for generated Java classes.
`--java-class-access-modifier <public/package>`	The access modifier to use for generated Java classes (default: `public`).
`--java-cpp-exception <exception-class>`	The type for translated C++ exceptions in Java (default: `java.lang.RuntimeException` that is not checked)
`--java-annotation <annotation-class>`	Java annotation (`@Foo`) to place on all generated Java classes
`--java-generate-interfaces <true/false>`	Whether Java interfaces should be used instead of abstract classes where possible (default: `false`).
`--java-nullable-annotation <nullable-annotation-class>`	Java annotation (`@Nullable`) to place on all fields and return values that are optional
`--java-nonnull-annotation <nonnull-annotation-class>`	Java annotation (`@Nonnull`) to place on all fields and return values that are not optional
`--java-implement-android-os-parcelable <true/false>`	all generated java classes will implement the interface `android.os.Parcelable`
`--java-use-final-for-record <use-final-for-record>`	Whether generated Java classes for records should be marked `final` (default: `true`).

C++¶

Argument	Description
`--cpp-out <out-folder>`	The output folder for C++ files (Generator disabled if unspecified).
`--cpp-header-out <out-folder>`	The output folder for C++ header files (default: the same as `--cpp-out`).
`--cpp-include-prefix <prefix>`	The prefix for `#includes` of header files from C++ files.
`--cpp-namespace ...`	The namespace name to use for generated C++ classes.
`--cpp-ext <ext>`	The filename extension for C++ files (default: `cpp`).
`--hpp-ext <ext>`	The filename extension for C++ header files (default: `hpp`).
`--cpp-optional-template <template>`	The template to use for optional values (default: `std::optional`)
`--cpp-optional-header <header>`	The header to use for optional values (default: `<optional>`)
`--cpp-enum-hash-workaround <true/false>`	Work around LWG-2148 by generating `std::hash` specializations for C++ enums (default: `true`)
`--cpp-nn-header <header>`	The header to use for non-nullable pointers
`--cpp-nn-type <header>`	The type to use for non-nullable pointers (as a substitute for `std::shared_ptr`)
`--cpp-nn-check-expression <header>`	The expression to use for building non-nullable pointers
`--cpp-use-wide-strings <true/false>`	Use wide strings in C++ code (default: `false`)
`--cpp-omit-default-record-constructor <true/false>`	Omit the default constructor for records in C++ code (default: `false`)
`--cpp-json-serialization <nlohmann_json>`	If specified, generate serializers to/from JSON and C++ types using nlohmann/json.

JNI¶

Argument	Description
`--jni-out <out-folder>`	The folder for the JNI C++ output files (Generator disabled if unspecified).
`--jni-header-out <out-folder>`	The folder for the JNI C++ header files (default: the same as `--jni-out`).
`--jni-include-prefix <prefix>`	The prefix for `#includes` of JNI header files from JNI C++ files.
`--jni-include-cpp-prefix <prefix>`	The prefix for `#includes` of the main header files from JNI C++ files.
`--jni-namespace ...`	The namespace name to use for generated JNI C++ classes.
`--jni-generate-main <true/false>`	Generate a source file (`djinni_jni_main.cpp`) that includes the default `JNI_OnLoad` & `JNI_OnUnload` implementation from the support library. (default: `true`)

Objective-C¶

Argument	Description
`--objc-out <out-folder>`	The output folder for Objective-C files (Generator disabled if unspecified).
`--objc-header-out <out-folder>`	The output folder for Objective-C header files (default: the same as `--objc-out`).
`--objc-h-ext <ext>`	The filename extension for Objective-C[++] header files (default: `h`)
`--objc-type-prefix <pre>`	The prefix for Objective-C data types (usually two or three letters)
`--objc-include-prefix <prefix>`	The prefix for `#import` of header files from Objective-C files.
`--objc-swift-bridging-header <name>`	The name of Objective-C Bridging Header used in XCode's Swift projects. The output folder is `--objc-header-out`.
`--objc-closed-enums <true/false>`	All generated Objective-C enums will be `NS_CLOSED_ENUM` (default: `false`).
`--objc-strict-protocols <true/false>`	All generated @protocol will implement (default: true).

Objective-C++¶

Argument	Description
`--objcpp-out <out-folder>`	The output folder for private Objective-C++ files (Generator disabled if unspecified).
`--objcpp-header-out <out-folder>`	The folder for the Objective-C++ header files (default: the same as `--objcpp-out`).
`--objcpp-ext <ext>`	The filename extension for Objective-C++ files (default: `mm`)
`--objcpp-include-prefix <prefix>`	The prefix for `#import` of Objective-C++ header files from Objective-C++ files.
`--objcpp-include-cpp-prefix <prefix>`	The prefix for `#include` of the main C++ header files from Objective-C++ files.
`--objcpp-include-objc-prefix <prefix>`	The prefix for `#import` of the Objective-C header files from Objective-C++ files (default: the same as `--objcpp-include-prefix`)
`--cpp-extended-record-include-prefix <prefix>`	The prefix path for `#include` of the extended record C++ header (`.hpp`) files
`--objc-extended-record-include-prefix <prefix>`	The prefix path for `#import` of the extended record Objective-C header (`.h`) files
`--objcpp-namespace <prefix>`	The namespace name to use for generated Objective-C++ classes.

Python¶

Argument	Description
`--py-out <out-folder>`	The output folder for Python files (Generator disabled if unspecified).
`--pycffi-out <out-folder>`	The output folder for PyCFFI files (Generator disabled if unspecified).
`--pycffi-package-name ...`	The package name to use for the generated PyCFFI classes.
`--pycffi-dynamic-lib-list ...`	The names of the dynamic libraries to be linked with PyCFFI.
`--py-import-prefix <import-prefix>`	The import prefix used within python generated files (default: "")

C wrapper¶

Argument	Description
`--c-wrapper-out <out-folder>`	The output folder for C wrapper files (Generator disabled if unspecified).
`--c-wrapper-header-out <out-folder>`	The output folder for C wrapper header files (default: the same as `--c-wrapper-out`).
`--c-wrapper-include-prefix <prefix>`	The prefix for #includes of C wrapper header files from C wrapper C++ files.
`--c-wrapper-include-cpp-prefix <prefix>`	The prefix for #includes of C++ header files from C wrapper C++ files.

C++/CLI¶

Argument	Description
`--cppcli-out <out-folder>`	The output folder for C++/CLI files (Generator disabled if unspecified).
`--cppcli-namespace ...`	The namespace name to use for generated C++/CLI classes.
`--cppcli-include-cpp-prefix <prefix>`	The prefix for `#include` of the main C++ header files from C++/CLI files.

Yaml Generation¶

Argument	Description
`--yaml-out <out-folder>`	The output folder for YAML files (Generator disabled if unspecified).
`--yaml-out-file <out-file>`	If specified all types are merged into a single YAML file instead of generating one file per type (relative to `--yaml-out`).
`--yaml-prefix <pre>`	The prefix to add to type names stored in YAML files (default: "").

Other¶

Argument	Description
`--list-in-files <list-in-files>`	Optional file in which to write the list of input files parsed.
`--list-out-files <list-out-files>`	Optional file in which to write the list of output files produced.
`--skip-generation <true/false>`	Way of specifying if file generation should be skipped (default: `false`)

Identifier Style¶

The Identifier Style is a text conversion hint on how to generate names from the djinni idl file.

Possible values: FooBar, fooBar, foo_bar, FOO_BAR, m_fooBar.

C++¶

Argument	Default
`--ident-cpp-enum`	`FOO_BAR`
`--ident-cpp-field`	`foo_bar`
`--ident-cpp-method`	`foo_bar`
`--ident-cpp-type`	`FooBar`
`--ident-cpp-enum-type`	`FooBar`
`--ident-cpp-type-param`	`FooBar`
`--ident-cpp-local`	`foo_bar`
`--ident-cpp-file`	`foo_bar`

Java¶

Argument	Default
`--ident-java-enum`	`FOO_BAR`
`--ident-java-field`	`fooBar`
`--ident-java-type`	`FooBar`
`--ident-jni-class`	`FooBar`
`--ident-jni-file`	`foo_bar`

Objective C¶

Argument	Default
`--ident-objc-enum`	`FooBar`
`--ident-objc-field`	`fooBar`
`--ident-objc-method`	`fooBar`
`--ident-objc-type`	`FooBar`
`--ident-objc-type-param`	`FooBar`
`--ident-objc-local`	`fooBar`
`--ident-objc-file`	`FooBar`

Python¶

Argument	Default
`--ident-py-type`	`foo_bar`
`--ident-py-class-name`	`FooBar`
`--ident-py-type-param`	`foo_bar`
`--ident-py-method`	`foo_bar`
`--ident-py-field`	`foo_bar`
`--ident-py-local`	`foo_bar`
`--ident-py-enum`	`Foo_Bar`
`--ident-py-const`	`FOO_BAR`

C++/CLI¶

Argument	Default
`--ident-cppcli-type`	`FooBar`
`--ident-cppcli-type-param`	`FooBar`
`--ident-cppcli-property`	`FooBar`
`--ident-cppcli-method`	`FooBar`
`--ident-cppcli-local`	`fooBar`
`--ident-cppcli-enum`	`FooBar`
`--ident-cppcli-const`	`FooBar`
`--ident-cppcli-file`	`FooBar`

Example:

The djinni idl for an enum

SomeEnum = enum {
    Value;
}

transforms per default to the following Java code

public enum SomeEnum {
    VALUE,
    ;
}

As you see, VALUE is now in upper case letters.

If you use --ident-java-enum foo_bar then Value will not be transformed into upper case and the following Java code will be generated.

public enum SomeEnum {
    Value,
    ;
}

This way you can adopt code generation to some extend to your existing coding style.

The best way to find out how that works is playing around with different values for different identifier options.

If you wish no text transformation to happen, use the foo_bar style.

Note

Some identifiers do have text transformation enabled by default. Nevertheless make sure to explicitly set text transformation styles if you need them! All text transformation may be disabled by default in a future release of the generator.

Last update: July 10, 2022