The tool class
A tool provides an (object-oriented) abstraction that encapsulates actions. In the context of a tool, actions become methods, with all the associated benefits. Following idiomatic object-oriented design, abstract tools provide an interface by defining abstract action methods, while subclasses implement them. Each derived tool class registers a new feature of the same name as the tool class with two subfeatures: name and version. For example, consider this simple tool hierarchy:
![digraph T {
rankdir="LR"
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cxx [ label="{ {cxx|cxx.name : feature\lcxx.version : feature\lcompile : action\l}}"]
gxx [ label="{ {gxx|gxx.name : feature\lgxx.version : feature\lcompile : action\l}}"]
"tool" -> "cxx" -> "gxx";
}](../_images/graphviz-c0b3b1dd26d203750367b00763f377c55c9437e1.png)
The value of these these feature variables will be determined by the actual instances of these classes, i.e. an instance of gxx will have cxx.name=gxx.name='gxx'. This mechanism allows for references to abstract actions such as cxx.compile to be resolved to concrete actions.
Constructor
-
tool(name='', version='') The tool name defaults to its class name.
Attributes
-
name Return the tool's name
-
version Return the tool's version string (defaults to '' if no version is known).
-
id Return the tool's id (a string combining name and version).
-
features Any features defined for this tool.
Methods
-
classmethod
instance(cls, features=None) Find an instance of cls that meets the feature requirements. Tools can be found by their (class) name, as well as the names of their base class(es).
Examples
Given a simple fabscript such as:
from faber.tools.cxx import cxx
rule(cxx.compile, 'hello.o', source='hello.cpp')
it becomes possible to configure your build environment by instantiating different compilers:
from faber.tools.gxx import gxx
gxx = gxx()
gxx11 = gxx(name='g++11', features=cxxflags('--std=c++11'))
gxx03 = gxx(name='g++03', features=cxxflags('--std=c++03'))
mingwxx = gxx(name='mingw++', command='/usr/bin/x86_64-w64-mingw32-g++')
Now you can invoke a build by selecting either of these to compile hello.o:
$ faber cxx.name=gxx
will invoke g++ ...,
$ faber cxx.name=g++11
will invoke g++ --std=c++11 ...,
$ faber cxx.name=mingw++
will invoke /usr/bin/x86_64-w64-mingw32-g++ ...