nimble/developers.markdown

Babel for developers

This file contains information mostly meant for developers willing to produce Nimrod modules and submit them to the nimrod-code/packages repository. End user documentation is provided in the readme.markdown file.

Libraries

When babel installs a library it will copy all the files that it downloaded into $babelDir/pkgs/pkgname-ver. It's up to the package creator to make sure that the package directory layout is correct, this is so that users of the package can correctly import the package.

By convention, it is suggested that the layout be as follows. The directory layout is determined by the nature of your package, that is, whether your package exposes only one module or multiple modules.

If your package exposes only a single module, then that module should be present in the root directory (the directory with the babel file) of your git repository, it is recommended that in this case you name that module whatever your package's name is. A good example of this is the jester package which exposes the jester module. In this case the jester package is imported with import jester.

If your package exposes multiple modules then the modules should be in a PackageName directory. This will allow for a certain measure of isolation from other packages which expose modules with the same names. In this case the package's modules will be imported with import PackageName/module.

You are free to combine the two approaches described.

In regards to modules which you do not wish to be exposed. You should place them in a PackageName/private directory. Your modules may then import these private modules with import PackageName/private/module. This directory structure may be enforced in the future.

All files and folders in the directory of where the .babel file resides will be copied as-is, you can however skip some directories or files by setting the SkipDirs, SkipFiles or SkipExt options in your .babel file. Directories and files can also be specified on a whitelist basis, if you specify either of InstallDirs, InstallFiles or InstallExt then babel will only install the files specified.

Example library .babel file

[Package]
name          = "ProjectName"
version       = "0.1.0"
author        = "Your Name"
description   = "Example .babel file."
license       = "MIT"

SkipDirs = "SomeDir" ; ./SomeDir will not be installed
SkipFiles = "file.txt,file2.txt" ; ./{file.txt, file2.txt} will not be installed
SkipFiles = """
  foo.txt
  foo2.rst
  foo3.md
""" ; Listing the files on multiple lines also works.

[Deps]
Requires: "nimrod >= 0.9.2"

All the fields (except SkipDirs and SkipFiles) under [Package] are required. [Deps] may be omitted.

Binary packages

These are application packages which require building prior to installation. A package is automatically a binary package as soon as it sets at least one bin value, like so:

bin = "main"

In this case when babel install is invoked, babel will build the main.nim file, copy it into $babelDir/pkgs/pkgname-ver/ and subsequently create a symlink to the binary in $babelDir/bin/. On Windows a stub .bat file is created instead.

Other files will be copied in the same way as they are for library packages.

Binary packages should not install .nim files so you should include SkipExt = "nim" in your .babel file, unless you intend for your package to be a binary/library combo which is fine.

Dependencies are automatically installed before building.

Dependencies

Dependencies are specified under the [Deps] section in a babel file. The requires key is used to specify them. For example:

[Deps]
Requires: "nimrod >= 0.9.2, jester > 0.1 & <= 0.5"

Dependency lists support version ranges. These versions may either be a concrete version like 0.1, or they may contain any of the less-than (<), greater-than (>), less-than-or-equal-to (<=) and greater-than-or-equal-to (>=). Two version ranges may be combined using the & operator for example: > 0.2 & < 1.0 which will install a package with the version greater than 0.2 and less than 1.0.

Versions

Versions of cloned packages via git or mercurial are determined through the repository's tags.

When installing a package which needs to be downloaded, after the download is complete and if the package is distributed through a VCS, babel will check the cloned repository's tags list. If no tags exist, babel will simply install the HEAD (or tip in mercurial) of the repository. If tags exist, babel will attempt to look for tags which resemble versions (e.g. v0.1) and will then find the latest version out of the available tags, once it does so it will install the package after checking out the latest version.

.babel reference

[Package]

Required

• name - The name of the package.
• version - The current version of this package. This should be incremented after tagging the current version using git tag or hg tag.
• author - The name of the author of this package.
• description - A string describing the package.
• license - The name of the license in which this package is licensed under.

Optional

• SkipDirs - A list of directory names which should be skipped during installation, separated by commas.
• SkipFiles - A list of file names which should be skipped during installation, separated by commas.
• SkipExt - A list of file extensions which should be skipped during installation, the extensions should be specified without a leading . and should be separated by commas.
• InstallDirs - A list of directories which should exclusively be installed, if this option is specified nothing else will be installed except the dirs listed here, the files listed in InstallFiles, the files which share the extensions listed in InstallExt, the .babel file and the binary (if bin is specified). Separated by commas.
• InstallFiles - A list of files which should be exclusively installed, this complements InstallDirs and InstallExt. Only the files listed here, directories listed in InstallDirs, files which share the extension listed in InstallExt, the .babel file and the binary (if bin is specified) will be installed. Separated by commas.
• InstallExt - A list of file extensions which should be exclusively installed, this complements InstallDirs and InstallFiles. Separated by commas.
• srcDir - Specifies the directory which contains the .nim source files. Default: The directory in which the .babel file resides; i.e. root dir of package.
• bin - A list of files which should be built separated by commas with no file extension required. This option turns your package into a binary package, babel will build the files specified and install them appropriately.
• backend - Specifies the backend which will be used to build the files listed in bin. Possible values include: c, cc, cpp, objc, js. Default: c

[Deps]/[Dependencies]

Optional

• requires - Specified a list of package names with an optional version range separated by commas. Example: nimrod >= 0.9.2, jester; with this value your package will depend on nimrod version 0.9.2 or greater and on any version of jester.

Submitting your package to the package list.

Babel's packages list is stored on github and everyone is encouraged to add their own packages to it! Take a look at nimrod-code/packages to learn more.