Recipe Hacking no. 2! Building on what we learnt during the first installment we will be working on more Conan 2.0 Migration! We'll start by reviewing some open pull requests and hopefully tackle a CMake example. Register here to attend.
- binary package
- Output binary usually obtained with a conan create command applying settings and options as input. Usually, there are N
binary packages inside one Conan package, one for each set of settings and options. Every
binary package is identified by a package_id.
- build helper
- A build helper is a Python script that translates Conan settings to the specific settings of a
build tool. For example, in the case of CMake, the build helper sets the CMake flag for
the generator from Conan settings like the compiler, operating system, and architecture. Conan
provides integration for several build tools such as CMake,
Autotools, MSBuild or
Meson. You can also integrate your preferred build system
in Conan if it is not available by default.
- build requirement
- Requirements that are only needed when you need to build a package (that declares the build requirement)
from sources, but if the binary package already exists, the build-require is not retrieved.
- build system
- Tools used to automate the process of building binaries from sources. Some examples are Make,
Autotools, SCons, CMake, Premake, Ninja or Meson. Conan has integrations with some of these
build systems using generators and build helpers.
- Can refer to either conanfile.txt or conanfile.py depending on what’s the context it is
- The file that defines a Conan recipe that is typically used to create packages, but can be used
also to consume packages only (see conanfile.txt). Inside of this recipe, it is defined (among
other things) how to download the package’s source code, how to build the binaries from those
sources, how to package the binaries and information for future consumers on how to consume
- It is a simplified version of the conanfile.py used only for consuming packages. It defines a
list of packages to be consumed by a project and can also define the
generators for the build system we are using, and if we want to
import files from the dependencies, as shared libraries, executables or
- cross compiler
- A cross compiler is a compiler capable of creating an executable intended to run in a platform
different from the one in which the compiler is running.
- dependency graph
- A directed graph representing dependencies of several Conan packages towards each other. The
relations between the packages are declared with the requirements in the recipes. A
dependency graph in Conan depends on the input profile applied because the requirements can be
conditioned to a specific configuration.
- editable package
- A package that resides in the user workspace, but is consumed as if
it was in the cache. This mode is useful when you are developing the packages, and the projects
that consume them at the same time.
- A generator provides the information of dependencies calculated by Conan in a suitable format
that is usually injected in a build system. They normally provide a file that can be included
or passed as input to the specific build system to help it to find the packages declared in the
recipe. There are other generators that are not intended to be used with the build system. e.g.
- Conan Hooks are Python scripts containing functions that will be executed before
and after a particular task performed by the Conan client. Those tasks could be Conan commands,
recipe interactions such as exporting or packaging, or interactions with the remotes. For
example, you could have a hook that checks that the recipe includes attributes like license,
url and description.
- A library is a collection of code and resources to be reused by other programs.
- local cache
- A folder in which Conan stores the package cache and some configuration files such as the
conan.conf or settings.yml. By default, this file will be located in the user home folder
~/.conan/ but it’s configurable with the environment variable
CONAN_USER_HOME. In some
scenarios like CI environments or when using per-project management and storage changing the
default conan cache location could be useful.
- Files that store the information with the exact versions, revisions, options, and configuration
of a dependency graph. They are intended to make the building process reproducible even if the
dependency definitions in conanfile recipes are not fully deterministic.
- Options are declared in the recipes, it is similar to
the setting concept but it is something that can be defaulted by the recipe creator, like if
a library is static or shared. Options are specific to each package (there is not a yml file
like the settings.yml file), and each package creator can define their options “header_only”
for example. The most common example is the “shared” option, with possibles values True/False
and typically defaulted to False.
- A Conan package is a collection of files that include the recipe and the N binary packages
generated for different configurations and settings. It can contain binary files such as
libraries, headers or tools to be reused by the consumer of the package.
- package ID
- The package id is a hash of the settings options and requirements used to identify the binary
packages. Applying different profiles to the conan create command, it will generate
different package IDs. e.g: Windows, x86, shared…
- package reference
- A package reference is the combination of the recipe reference and the package ID. It adopts
the form of
- package revision
- A unique ID using the checksum of the package (all files stored in a binary package). See the revisions mechanism page.
- A profile is the set of different settings, options, environment
variables and build requirements used when working with packages. The settings define the
operating system, architecture, compiler, build type, and C++ standard. Options define, among
other things, if dependencies are linked in shared or static mode or other compile options.
- Python script defined in a conanfile.py that specifies how the package is built from sources,
what the final binary artifacts are, the package dependencies, etc.
- recipe reference
- A recipe reference is the combination of the package name, version, and two optional fields
named user and channel that could be useful to identify a forked recipe from the community with
changes specific to your company. It adopts the form of
- recipe revision
- A unique ID using the latest VCS hash or a checksum of the conanfile.py with
the exported files if any. See the revisions mechanism page.
- The binary repository that hosts Conan packages inside a server.
- Packages on which another package depends on. They are represented by a conan reference:
- It is the mechanism to implicitly version the changes done in a recipe or
package without bumping the actual reference or package version.
- semantic versioning
- Versioning system with versions in the form of
changes when you make backward-compatible bug fixes,
MINOR version changes when you add
functionality in a backward-compatible manner, and
MAJOR version changes when you make
incompatible API changes. Conan uses semantic versioning by default but this behavior can be
easily configured and changed in the
of your conanfile, and any versioning scheme you desire is supported.
- A set of keys and values, like os, compiler and build_type that are declared at the
- shared library
- A library that is loaded at runtime into the target application.
- static library
- A library that is copied at compile time to the target application.
- system packages
- System packages are packages that are typically installed system-wide via system package
management tools such as apt, yum, pkg, pkgutil, brew or pacman. It is possible to install
system-wide packages methods from Conan adding a
system_requirements() method to the conanfile.
- A toolchain is the set of tools usually intended for compiling, debugging and profiling
- transitive dependency
- A dependency that is induced by the dependency that the program references directly. Imagine
that your project uses the Poco library that needs the OpenSSL library, and OpenSSL
is calling to the zlib library. In this case, OpenSSL and zlib would be transitive
- Conan workspaces allow us to have more than one package in user folders and
have them directly use other packages from user folders without needing to put them in the
local cache. Furthermore, they enable incremental builds on large projects containing multiple