Modules

A module in BL is a chunk of reusable multi-platform code bundled with a configuration file in a single module root directory. See the following example of the thread module.

thread/
  module.yaml       - module config
  _thread.win32.bl  - windows implementation
  _thread.posix.bl  - posix implementation
  thread.bl         - interface
  thread.test.bl    - unit tests

Modules can be imported into other projects using the #import directive followed by the module root directory path. The configuration file module.yaml is mandatory for each module and must be located in the module root directory. In general, the configuration file tells the compiler which source files should be loaded, which libraries are needed and what is the module version. See the module configuration example.

version: 20221021

x86_64-pc-windows-msvc:
  src: "_thread.win32.bl"

x86_64-pc-linux-gnu:
  src: "_thread.posix.bl"

x86_64-apple-darwin:
  src: "_thread.posix.bl"

arm64-apple-darwin:
  src: "_thread.posix.bl"

The first in the file is the version of the module (usually in the format YYYYMMDD) followed by the list of all compilation targets supported by the module. In this example, we use a different implementation for Windows. You can get a list of all supported platforms using the blc --target-supported command.

To import the thread module use the root directory path:

#import "path/to/module/thread"

See also Module Import Policy.

List of module config entries

The configuration file entries may be global or platform-specific, see the following sections.

Global Options

The global options are applied to the module on all target platforms.

• version: <N> - Module version number used during import to distinguish various versions of the same module, see also ModuleImportPolicy for more information.

Global or Platform-Specific Options

All the following options may be applied globally or just for a specific target platform.

• src: "<FILE1[;FILE2;...]>" - List of source file paths relative to the module root directory separated by platform-specific separator (: on Windows and ; on Unix).
• linker_opt: "<OPTIONS>" - Additional runtime linker options.
• linker_lib_path: "<DIR1;[DIR2;...]>" - Additional linker lookup directories relative to the module root directory.
• link: "<LIB1[;LIB2;...]> - Libraries to link. Note that libraries listed here are dynamically loaded during compilation (may be executed in compile-time).

# The version is required to be global.
version: 20221021

# Load this file on all platforms. 
src: "my_file_imported_everytime.bl"

# Section specific for Windows.
x86_64-pc-windows-msvc:
  src: "my_file_only_for_windows.bl"

# Section specific for Linux.
x86_64-pc-linux-gnu:
  src: "my_file_only_for_linux.bl"
  linker_opt: "-lc -lm" # link these only on linux