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The JUCE Module Format
A JUCE module is a collection of header and source files which can be added to a project
to provide a set of classes and libraries or related functionality.
Their structure is designed to make it as simple as possible for modules to be added to
user projects on many platforms, either via automated tools, or by manual inclusion.
Each module may have dependencies on other modules, but should be otherwise self-contained.
File structure
Each module lives inside a folder whose name is the same as the name of the module. The
JUCE convention for naming modules is lower-case with underscores, e.g.
But any name that is a valid C++ identifer is OK.
Inside the root of this folder, there must be a set of public header and source files which
the user's' project will include. The module may have as many other internal source files as
it needs, but these must all be inside sub-folders!
Master header file
In this root folder there must be ONE master header file, which includes all the necessary
header files for the module. This header must have the same name as the module, with
a .h/.hpp/.hxx suffix. E.g.
IMPORTANT! All code within a module that includes other files from within its own subfolders
must do so using RELATIVE paths!
A module must be entirely relocatable on disk, and it must not rely on the user's project
having any kind of include path set up correctly for it to work. Even if the user has no
include paths whatsoever and includes the module's master header via an absolute path,
it must still correctly find all of its internally included sub-files.
This master header file must also contain a comment with a BEGIN_JUCE_MODULE_DECLARATION
block which defines the module's requirements - the syntax for this is described later on..
Module CPP files
A module consists of a single header file and zero or more .cpp files. Fewer is better!
Ideally, a module could be header-only module, so that a project can use it by simply
including the master header file.
For various reasons it's usually necessary or preferable to have a simpler header and
some .cpp files that the user's project should compile as stand-alone compile units.
In this case you should ideally provide just a single cpp file in the module's root
folder, and this should internally include all your other cpps from their sub-folders,
so that only a single cpp needs to be added to the user's project in order to completely
compile the module.
In some cases (e.g. if your module internally relies on 3rd-party code which can't be
easily combined into a single compile-unit) then you may have more than one source file
here, but avoid this if possible, as it will add a burden for users who are manually
adding these files to their projects.
The names of these source files must begin with the name of the module, but they can have
a number or other suffix if there is more than one.
In order to specify that a source file should only be compiled on a specific platform,
then the filename can be suffixed with one of the following strings:
juce_mymodule/juce_mymodule_1.cpp <- compiled on all platforms
juce_mymodule/juce_mymodule_2.cpp <- compiled on all platforms
juce_mymodule/juce_mymodule_OSX.cpp <- compiled only on OSX
juce_mymodule/juce_mymodule_Windows.cpp <- compiled only on Windows
Often this isn't necessary, as in most cases you can easily add checks inside the files
to do different things depending on the platform, but this may be handy just to avoid
clutter in user projects where files aren't needed.
To simplify the use of obj-C++ there's also a special-case rule: If the folder contains
both a .mm and a .cpp file whose names are otherwise identical, then on OSX/iOS the .mm
will be used and the cpp ignored. (And vice-versa for other platforms, of course).
Precompiled libraries
Precompiled libraries can be included in a module by placing them in a libs/ subdirectory.
The following directories are automatically added to the library search paths, and libraries
placed in these directories can be linked with projects via the OSXLibs, iOSLibs,
windowsLibs, linuxLibs and mingwLibs keywords in the module declaration (see the following
libs/MacOSX/{arch}, where {arch} is the architecture you are targeting in Xcode ("x86_64" or
"i386", for example).
Visual Studio:
VisualStudio{year}/{arch}/{run-time}, where {year} is the four digit year of the Visual Studio
release, arch is the target architecture in Visual Studio ("x64" or "Win32", for example), and
{runtime} is the type of the run-time library indicated by the corresponding compiler flag
("MD", "MDd", "MT", "MTd").
libs/Linux/{arch}, where {arch} is the architecture you are targeting with the compiler. Some
common examples of {arch} are "x86_64", "i386" and "armv6".
libs/MinGW/{arch}, where {arch} can take the same values as Linux.
libs/iOS/{arch}, where {arch} is the architecture you are targeting in Xcode ("arm64" or
"x86_64", for example).
libs/Android/{arch}, where {arch} is the architecture provided by the Android Studio variable
"${ANDROID_ABI}" ("x86", "armeabi-v7a", "mips", for example).
This block of text needs to go inside the module's main header file. It should be commented-out
and perhaps inside an #if 0 block too, but the Introjucer will just scan the whole file for the
string BEGIN_JUCE_MODULE_DECLARATION, and doesn't care about its context in terms of C++ syntax.
The block needs a corresponding END_JUCE_MODULE_DECLARATION to finish the block.
These should both be on a line of their own.
Inside the block, the parser will expect to find a list of value definitions, one-per-line, with
the very simple syntax
value_name: value
The value_name must be one of the items listed below, and is case-sensitive. Whitespace on the
line is ignored. Some values are compulsory and must be supplied, but others are optional.
The order in which they're declared doesn't matter.
Possible values:
ID: (Compulsory) This ID must match the name of the file and folder, e.g. juce_core.
The main reason for also including it here is as a sanity-check
vendor: (Compulsory) A unique ID for the vendor, e.g. "juce". This should be short
and shouldn't contain any spaces
version: (Compulsory) A version number for the module
name: (Compulsory) A short description of the module
description: (Compulsory) A longer description (but still only one line of text, please!)
dependencies: (Optional) A list (space or comma-separated) of other modules that are required by
this one. The Introjucer can use this to auto-resolve dependencies.
website: (Optional) A URL linking to useful info about the module]
license: (Optional) A description of the type of software license that applies
minimumCppStandard: (Optional) A number indicating the minimum C++ language standard that is required for this module.
This must be just the standard number with no prefix e.g. 14 for C++14
searchpaths: (Optional) A space-separated list of internal include paths, relative to the module's
parent folder, which need to be added to a project's header search path
OSXFrameworks: (Optional) A list (space or comma-separated) of OSX frameworks that are needed
by this module
iOSFrameworks: (Optional) Like OSXFrameworks, but for iOS targets
linuxPackages: (Optional) A list (space or comma-separated) pkg-config packages that should be used to pass
compiler (CFLAGS) and linker (LDFLAGS) flags
linuxLibs: (Optional) A list (space or comma-separated) of static or dynamic libs that should be linked in a
linux build (these are passed to the linker via the -l flag)
mingwLibs: (Optional) A list (space or comma-separated) of static libs that should be linked in a
win32 mingw build (these are passed to the linker via the -l flag)
OSXLibs: (Optional) A list (space or comma-separated) of static or dynamic libs that should be linked in an
OS X build (these are passed to the linker via the -l flag)
iOSLibs: (Optional) A list (space or comma-separated) of static or dynamic libs that should be linked in an
iOS build (these are passed to the linker via the -l flag)
windowsLibs: (Optional) A list (space or comma-separated) of static or dynamic libs that should be linked in a
Visual Studio build (without the .lib suffixes)
Here's an example block:
ID: juce_audio_devices
vendor: juce
version: 4.1.0
name: JUCE audio and MIDI I/O device classes
description: Classes to play and record from audio and MIDI I/O devices
license: GPL/Commercial
dependencies: juce_audio_basics, juce_audio_formats, juce_events
OSXFrameworks: CoreAudio CoreMIDI DiscRecording
iOSFrameworks: CoreAudio CoreMIDI AudioToolbox AVFoundation
linuxLibs: asound
mingwLibs: winmm