Targets¶
As a build system, Rabs works on targets. A target is anything that can be built or changed, both by the build and externally. Each time Rabs is run, it takes the necessary actions to ensure a particular target is up to date. This may involve checking other targets, and rebuilding them as necessary.
Every target has the following attributes:
- A unique identifier
Every target has a unique identifer. Likewise, every identifier corresponds to a unique target. This allows targets to be referenced across multiple scripts within a build.
Some examples of identifiers:
file("test.c")has identifier"file:test.c".meta("NAME")has identifier"meta:context path:NAME"where context path is the path of the enclosing context.
- An optional build function
A target can have a build function which is called whenever the target needs to be rebuilt, or if the target is missing. To set the build function for a target, use the
=>operator:- Optional dependencies
A target can depend on other targets. If any dependency of a target is changed during a build then the target itself will be rebuilt (assuming it has a build function) and rechecked. To add dependencies to a target, use the
[]operator. Both individual dependencies and lists of dependencies are accepted.- A SHA-256 checksum
Every target has a checksum created once the target is built. If the target is rebuilt, or possibly changed externally, a new checksum is calculated and compared to the previous one. If the checksum has changed, then the target is considered updated.
Methods¶
Every target supports the following methods:
Target => BuildFunction
Sets the build function for Target to BuildFunction.
Target[Dependency, Dependency, ...]
Adds dependencies to Target. Each dependency can itself be a list of further dependencies, in case the list of dependencies is generated by code.
Target:scan(Name)
Creates a scan target called Name associated with Target. See Scan Targets for more details.
Some target types provide other methods, these are documented in the respective sections.