Design notes

This is not really readable at the moment, mostly some personal notes about current internal design.

Bento is currently split into two parts: a core API to parse the package description into a simple object API, and a commands library which gives a command line interface to bento.

The main design philosophy of bento is to clearly separate the different stages of packaging deployment, as we believe it is the only way to make a build tool extensible.

Commands “protocol”

The command line interface of bento currently supports 3 stages:

  • configuration: is concerned with configuring user options (build/install customization).
  • build: compile C extensions
  • install: deploy the software into the system as configured at the first stage. Installers are considered installation as well for reasons explained later.

Although those stages are very similar to distutils/setuptools mechanism, the implementation is fundamentally different, because each stage is mostly independent from each other. No python object is directly shared between commands - the current bentomaker implementation implements each stage as a separate run. Once configured, every command has access to all options.

Build manifest and building installers

Bento uses a slightly unusal process to install the bits of your package. Instead of copying directly the files to the desired location, the install process is driven by a build manifest. This build manifest is produced by the build command. It contains a description of files per category as well as a few metadata. The syntax is based of JSON so that it can easily be parsed from any language and in most environments (local machine, browser, etc...).

Format internals

(This is likely to change in the future)

The json file contains 4 elements:

  • meta: this contains the metadata (as defined in the relevant packaging PEP)
  • install_paths: a dict of the configured paths
  • file_sections: a list of so-called file sections
  • executables: a list of executable sections

File sections

A list of dictionaries. Each dictionary contains:

  • category: the category name
  • name: name of this section
  • files: a list of tuple source -> target
  • source_dir: os.path.join(source_dir, source) gives an absolute path for each source file
  • target_dir: os.path.join(target_dir, target) gives an absolute path for each target file

Note that both source_dir and target_dir can refer to path variables as defined in the install_paths section. This allows to “retarget” a build tree to different tree configurations, as required by different packages formats.


"category": "executables",
     "files": [
     "name": "bentomaker",
     "source_dir": "$_srcrootdir/scripts-2.7",
     "target_dir": "$bindir"

This is interpreted as installing the file $_srcrootdir/scripts-2.7/bentomaker-2.7 into $bindir/bentomaker.


The built bits and the build manifest are enough to install the software to arbitrary location, so that the install process does not need to know anything about the build process. Conversely, as long as you can produce a build manifest, you can use the installation commands as is.

Besides installation, the manifest is also used to produce installers. Currently, windows installers (both .exe and .msi), eggs and mpkg are supported, and adding new types of installers should be easier than with distutils. If you look at the build_wininst and build_egg commands source code, they are simple, and most of the “magic” happens in the build manifest. In particular, the build manifest still refers to installed bits relatively to abstract paths, and those paths are resolved when building the installers.

Installers conversion

The build manifest is intended to be included in each produced installer, for convertion between various formats. The goal is to have idempotent conversions (e.g. converting an egg to wininst and then converting it back to an egg produces the exact same egg).

We also intend to use build manifest for the upcoming ‘’nest’’ service, which will contain a database of installed software.