TaskGen

Task generators

The class waflib.TaskGen.task_gen encapsulates the creation of task objects (low-level code) The instances can have various parameters, but the creation of task nodes (Task.py) is deferred. To achieve this, various methods are called from the method “apply”

waflib.TaskGen.feats = {'*': {'process_rule', 'process_source'}, 'asm': {'apply_incpaths', 'apply_link', 'apply_nasm_vars', 'propagate_uselib_vars'}, 'c': {'apply_flags_msvc', 'apply_incpaths', 'apply_link', 'process_use', 'propagate_uselib_vars', 'set_macosx_deployment_target'}, 'cprogram': {'apply_manifest', 'create_task_macapp', 'create_task_macplist', 'set_full_paths_hpux'}, 'cs': {'apply_cs', 'debug_cs', 'doc_cs', 'propagate_uselib_vars', 'use_cs'}, 'cshlib': {'apply_bundle', 'apply_implib', 'apply_manifest', 'apply_vnum'}, 'cxx': {'apply_flags_msvc', 'apply_incpaths', 'apply_link', 'process_use', 'propagate_uselib_vars', 'set_macosx_deployment_target'}, 'cxxprogram': {'apply_manifest', 'create_task_macapp', 'create_task_macplist', 'set_full_paths_hpux'}, 'cxxshlib': {'apply_bundle', 'apply_implib', 'apply_manifest', 'apply_vnum'}, 'd': {'apply_incpaths', 'apply_link', 'process_header', 'process_use', 'propagate_uselib_vars'}, 'dshlib': {'apply_vnum'}, 'fake_lib': {'process_lib'}, 'fake_obj': {'process_objs'}, 'fc': {'apply_flags_ifort', 'apply_incpaths', 'apply_link', 'process_use', 'propagate_uselib_vars'}, 'fcprogram': {'apply_manifest_ifort'}, 'fcprogram_test': {'apply_manifest_ifort'}, 'fcshlib': {'apply_implib', 'apply_manifest_ifort', 'apply_vnum'}, 'glib2': {'process_settings'}, 'grep_for_endianness': {'grep_for_endianness_fun'}, 'gresource': {'process_gresource_bundle'}, 'includes': {'apply_incpaths'}, 'install_task': {'process_install_task'}, 'intltool_in': {'apply_intltool_in_f'}, 'intltool_po': {'apply_intltool_po'}, 'jar': {'jar_files', 'use_jar_files'}, 'javac': {'apply_java', 'propagate_uselib_vars', 'set_classpath', 'use_javac_files'}, 'javadoc': {'create_javadoc'}, 'link_lib_test': {'link_lib_test_fun'}, 'link_main_routines_func': {'link_main_routines_tg_method'}, 'perlext': {'init_perlext'}, 'py': {'feature_py'}, 'pyembed': {'init_pyembed'}, 'pyext': {'init_pyext', 'set_bundle', 'set_lib_pat'}, 'qt5': {'apply_qt5', 'process_mocs'}, 'qt6': {'apply_qt5', 'process_mocs'}, 'rubyext': {'apply_ruby_so_name', 'init_rubyext'}, 'seq': {'sequence_order'}, 'skip_stlib_link_deps': {'apply_skip_stlib_link_deps'}, 'subst': {'process_subst'}, 'test': {'make_test'}, 'test_exec': {'test_exec_fun'}, 'test_scripts': {'make_interpreted_test'}, 'tex': {'apply_tex'}, 'use': {'process_use'}, 'uselib': {'propagate_uselib_vars'}, 'vnum': {'apply_vnum'}}

remember the methods declaring features

class waflib.TaskGen.task_gen(*k, **kw)

Instances of this class create waflib.Task.Task when calling the method waflib.TaskGen.task_gen.post() from the main thread. A few notes:

• The methods to call (self.meths) can be specified dynamically (removing, adding, ..)

• The ‘features’ are used to add methods to self.meths and then execute them

• The attribute ‘path’ is a node representing the location of the task generator

• The tasks created are added to the attribute tasks

• The attribute ‘idx’ is a counter of task generators in the same path

mappings = {'.ASM': <function asm_hook>, '.C': <function cxx_hook>, '.D': <function d_hook>, '.F': <function fc_hook>, '.F03': <function fc_hook>, '.F08': <function fc_hook>, '.F90': <function fc_hook>, '.F95': <function fc_hook>, '.FOR': <function fc_hook>, '.S': <function asm_hook>, '.SPP': <function asm_hook>, '.asm': <function asm_hook>, '.c': <function c_hook>, '.c++': <function cxx_hook>, '.cc': <function cxx_hook>, '.cpp': <function cxx_hook>, '.cxx': <function cxx_hook>, '.d': <function d_hook>, '.di': <function d_hook>, '.f': <function fc_hook>, '.f03': <function fc_hook>, '.f08': <function fc_hook>, '.f90': <function fc_hook>, '.f95': <function fc_hook>, '.for': <function fc_hook>, '.gresource.xml': <function process_gresource_source>, '.gs': <function vala_file>, '.l': <function declare_chain.<locals>.x_file>, '.lua': <function add_lua>, '.o': <function add_those_o_files>, '.obj': <function add_those_o_files>, '.pc.in': <function add_pcfile>, '.py': <function process_py>, '.qrc': <function create_rcc_task>, '.rb': <function process>, '.rc': <function rc_file>, '.s': <function asm_hook>, '.spp': <function asm_hook>, '.ts': <function add_lang>, '.ui': <function create_uic_task>, '.vala': <function vala_file>, '.vapi': <function vapi_file>, '.xs': <function xsubpp_file>, '.y': <function big_bison>, '.yc': <function big_bison>, '.yy': <function big_bison>}

Mappings are global file extension mappings that are retrieved in the order of definition

prec = {'apply_bundle': {'apply_link', 'init_pyext', 'propagate_uselib_vars'}, 'apply_cs': {'debug_cs', 'process_source', 'use_cs'}, 'apply_intltool_in_f': {'process_source'}, 'apply_java': {'jar_files', 'process_source', 'set_classpath', 'use_javac_files'}, 'apply_link': {'apply_flags_ifort', 'apply_flags_msvc', 'apply_implib', 'apply_manifest', 'apply_manifest_ifort', 'apply_qt5', 'apply_vnum', 'create_task_macapp', 'create_task_macplist', 'grep_for_endianness_fun', 'make_test', 'process_use', 'set_full_paths_hpux', 'test_exec_fun'}, 'apply_ruby_so_name': {'apply_link', 'propagate_uselib_vars'}, 'apply_skip_stlib_link_deps': {'process_use'}, 'apply_tex': {'process_source'}, 'debug_cs': {'doc_cs'}, 'feature_py': {'process_source'}, 'init_perlext': {'apply_incpaths', 'apply_link', 'propagate_uselib_vars'}, 'init_pyembed': {'propagate_uselib_vars'}, 'init_pyext': {'apply_link', 'propagate_uselib_vars'}, 'init_rubyext': {'apply_bundle', 'apply_incpaths', 'apply_link', 'process_source'}, 'jar_files': {'process_source', 'use_jar_files'}, 'link_lib_test_fun': {'process_source'}, 'link_main_routines_tg_method': {'process_source'}, 'process_dbus': {'process_source'}, 'process_enums': {'process_source'}, 'process_install_task': {'process_rule', 'process_source'}, 'process_marshal': {'process_source'}, 'process_mocs': {'process_source'}, 'process_objs': {'process_source'}, 'process_rule': {'create_javadoc', 'process_source'}, 'process_source': {'apply_incpaths', 'apply_link', 'process_use'}, 'process_subst': {'process_rule', 'process_source'}, 'process_use': {'apply_incpaths', 'make_test', 'propagate_uselib_vars', 'set_full_paths_hpux'}, 'propagate_uselib_vars': {'apply_incpaths', 'apply_vnum', 'set_classpath'}, 'set_bundle': {'apply_bundle', 'apply_link'}, 'set_lib_pat': {'apply_link', 'propagate_uselib_vars'}, 'use_cs': {'debug_cs'}, 'use_javac_files': {'jar_files', 'propagate_uselib_vars', 'set_classpath'}}

Dict that holds the precedence execution rules for task generator methods

__init__(*k, **kw)

Task generator objects predefine various attributes (source, target) for possible processing by process_rule (make-like rules) or process_source (extensions, misc methods)

Tasks are stored on the attribute ‘tasks’. They are created by calling methods listed in self.meths or referenced in the attribute features A topological sort is performed to execute the methods in correct order.

The extra key/value elements passed in kw are set as attributes

meths

List of method names to execute (internal)

features

List of feature names for bringing new methods in

tasks

Tasks created are added to this list

__str__()

Debugging helper

__repr__()

Debugging helper

get_cwd()

Current working directory for the task generator, defaults to the build directory. This is still used in a few places but it should disappear at some point as the classes define their own working directory.

Return type

waflib.Node.Node

get_name()

If the attribute name is not set on the instance, the name is computed from the target name:

def build(bld):
        x = bld(name='foo')
        x.get_name() # foo
        y = bld(target='bar')
        y.get_name() # bar

Return type

string

Returns

name of this task generator

property name

If the attribute name is not set on the instance, the name is computed from the target name:

def build(bld):
        x = bld(name='foo')
        x.get_name() # foo
        y = bld(target='bar')
        y.get_name() # bar

Return type

string

Returns

name of this task generator

to_list(val)

Ensures that a parameter is a list, see waflib.Utils.to_list()

Parameters

val (string or list of string) – input to return as a list

Return type

list

post()

Creates tasks for this task generators. The following operations are performed:

1. The body of this method is called only once and sets the attribute posted

2. The attribute features is used to add more methods in self.meths

3. The methods are sorted by the precedence table self.prec or :waflib:attr:waflib.TaskGen.task_gen.prec

4. The methods are then executed in order

5. The tasks created are added to waflib.TaskGen.task_gen.tasks

get_hook(node)

Returns the @extension method to call for a Node of a particular extension.

Parameters

node (waflib.Tools.Node.Node) – Input file to process

Returns

A method able to process the input node by looking at the extension

Return type

function

create_task(name, src=None, tgt=None, **kw)

Creates task instances.

Parameters

• name (string) – task class name

• src (list of waflib.Tools.Node.Node) – input nodes

• tgt (list of waflib.Tools.Node.Node) – output nodes

Returns

A task object

Return type

waflib.Task.Task

clone(env)

Makes a copy of a task generator. Once the copy is made, it is necessary to ensure that the it does not create the same output files as the original, or the same files may be compiled several times.

Parameters

env (waflib.ConfigSet.ConfigSet) – A configuration set

Returns

A copy

Return type

waflib.TaskGen.task_gen

process_dbus()

Processes the dbus files stored in the attribute dbus_lst to create waflib.Tools.dbus.dbus_binding_tool instances.

process_enums()

Processes the enum files stored in the attribute enum_list to create waflib.Tools.glib2.glib_mkenums instances.

process_marshal()

Processes the marshal files stored in the attribute marshal_list to create waflib.Tools.glib2.glib_genmarshal instances. Adds the c file created to the list of source to process.

waflib.TaskGen.declare_chain(name='', rule=None, reentrant=None, color='BLUE', ext_in=[], ext_out=[], before=[], after=[], decider=None, scan=None, install_path=None, shell=False)

Creates a new mapping and a task class for processing files by extension. See Tools/flex.py for an example.

Parameters

• name (string) – name for the task class

• rule (string or function) – function to execute or string to be compiled in a function

• reentrant (int) – re-inject the output file in the process (done automatically, set to 0 to disable)

• color (string) – color for the task output

• ext_in (list of string) – execute the task only after the files of such extensions are created

• ext_out (list of string) – execute the task only before files of such extensions are processed

• before (list of string) – execute instances of this task before classes of the given names

• after (list of string) – execute instances of this task after classes of the given names

• decider (function) – if present, function that returns a list of output file extensions (overrides ext_out for output files, but not for the build order)

• scan (function) – scanner function for the task

• install_path (string) – installation path for the output nodes

waflib.TaskGen.taskgen_method(func)

Decorator that registers method as a task generator method. The function must accept a task generator as first parameter:

from waflib.TaskGen import taskgen_method
@taskgen_method
def mymethod(self):
        pass

Parameters

func (function) – task generator method to add

Return type

function

waflib.TaskGen.feature(*k)

Decorator that registers a task generator method that will be executed when the object attribute feature contains the corresponding key(s):

from waflib.TaskGen import feature
@feature('myfeature')
def myfunction(self):
        print('that is my feature!')
def build(bld):
        bld(features='myfeature')

Parameters

k (list of string) – feature names

waflib.TaskGen.before_method(*k)

Decorator that registera task generator method which will be executed before the functions of given name(s):

from waflib.TaskGen import feature, before
@feature('myfeature')
@before_method('fun2')
def fun1(self):
        print('feature 1!')
@feature('myfeature')
def fun2(self):
        print('feature 2!')
def build(bld):
        bld(features='myfeature')

Parameters

k (list of string) – method names

waflib.TaskGen.before(*k)

Decorator that registera task generator method which will be executed before the functions of given name(s):

from waflib.TaskGen import feature, before
@feature('myfeature')
@before_method('fun2')
def fun1(self):
        print('feature 1!')
@feature('myfeature')
def fun2(self):
        print('feature 2!')
def build(bld):
        bld(features='myfeature')

Parameters

k (list of string) – method names

waflib.TaskGen.after_method(*k)

Decorator that registers a task generator method which will be executed after the functions of given name(s):

from waflib.TaskGen import feature, after
@feature('myfeature')
@after_method('fun2')
def fun1(self):
        print('feature 1!')
@feature('myfeature')
def fun2(self):
        print('feature 2!')
def build(bld):
        bld(features='myfeature')

Parameters

k (list of string) – method names

waflib.TaskGen.after(*k)

Decorator that registers a task generator method which will be executed after the functions of given name(s):

from waflib.TaskGen import feature, after
@feature('myfeature')
@after_method('fun2')
def fun1(self):
        print('feature 1!')
@feature('myfeature')
def fun2(self):
        print('feature 2!')
def build(bld):
        bld(features='myfeature')

Parameters

k (list of string) – method names

waflib.TaskGen.extension(*k)

Decorator that registers a task generator method which will be invoked during the processing of source files for the extension given:

from waflib import Task
class mytask(Task):
        run_str = 'cp ${SRC} ${TGT}'
@extension('.moo')
def create_maa_file(self, node):
        self.create_task('mytask', node, node.change_ext('.maa'))
def build(bld):
        bld(source='foo.moo')

waflib.TaskGen.to_nodes(self, lst, path=None)

Task generator method

Flatten the input list of string/nodes/lists into a list of nodes.

It is used by waflib.TaskGen.process_source() and waflib.TaskGen.process_rule(). It is designed for source files, for folders, see waflib.Tools.ccroot.to_incnodes():

Parameters

• lst (list of string and nodes) – input list

• path (waflib.Tools.Node.Node) – path from which to search the nodes (by default, waflib.TaskGen.task_gen.path)

Return type

list of waflib.Tools.Node.Node

waflib.TaskGen.process_source(self)

Task generator method

Processes each element in the attribute source by extension.

1. The source list is converted through waflib.TaskGen.to_nodes() to a list of waflib.Node.Node first.

2. File extensions are mapped to methods having the signature: def meth(self, node) by waflib.TaskGen.extension()

3. The method is retrieved through waflib.TaskGen.task_gen.get_hook()

4. When called, the methods may modify self.source to append more source to process

5. The mappings can map an extension or a filename (see the code below)

Feature

all

waflib.TaskGen.process_rule(self)

Task generator method

Processes the attribute rule. When present, waflib.TaskGen.process_source() is disabled:

def build(bld):
        bld(rule='cp ${SRC} ${TGT}', source='wscript', target='bar.txt')

Main attributes processed:

• rule: command to execute, it can be a tuple of strings for multiple commands

• chmod: permissions for the resulting files (integer value such as Utils.O755)

• shell: set to False to execute the command directly (default is True to use a shell)

• scan: scanner function

• vars: list of variables to trigger rebuilds, such as CFLAGS

• cls_str: string to display when executing the task

• cls_keyword: label to display when executing the task

• cache_rule: by default, try to re-use similar classes, set to False to disable

• source: list of Node or string objects representing the source files required by this task

• target: list of Node or string objects representing the files that this task creates

• cwd: current working directory (Node or string)

• stdout: standard output, set to None to prevent waf from capturing the text

• stderr: standard error, set to None to prevent waf from capturing the text

• timeout: timeout for command execution (Python 3)

• always: whether to always run the command (False by default)

• deep_inputs: whether the task must depend on the input file tasks too (False by default)

Feature

all

Before

waflib.TaskGen.process_source()

waflib.TaskGen.sequence_order(self)

Task generator method

Adds a strict sequential constraint between the tasks generated by task generators. It works because task generators are posted in order. It will not post objects which belong to other folders.

Example:

bld(features='javac seq')
bld(features='jar seq')

To start a new sequence, set the attribute seq_start, for example:

obj = bld(features='seq')
obj.seq_start = True

Note that the method is executed in last position. This is more an example than a widely-used solution.

Feature

seq

class waflib.TaskGen.subst_pc(*k, **kw)

Creates .pc files from .pc.in. The task is executed whenever an input variable used in the substitution changes.

hasrun

generator

env

waflib.ConfigSet.ConfigSet object (make sure to provide one)

inputs

List of input nodes, which represent the files used by the task instance

outputs

List of output nodes, which represent the files created by the task instance

dep_nodes

List of additional nodes to depend on

run_after

Set of tasks that must be executed before this one

hcode = b'\tdef run(self):\n\t\t"Substitutes variables in a .in file"\n\n\t\tif getattr(self.generator, \'is_copy\', None):\n\t\t\tfor i, x in enumerate(self.outputs):\n\t\t\t\tx.write(self.inputs[i].read(\'rb\'), \'wb\')\n\t\t\t\tstat = os.stat(self.inputs[i].abspath()) # Preserve mtime of the copy\n\t\t\t\tos.utime(self.outputs[i].abspath(), (stat.st_atime, stat.st_mtime))\n\t\t\tself.force_permissions()\n\t\t\treturn None\n\n\t\tif getattr(self.generator, \'fun\', None):\n\t\t\tret = self.generator.fun(self)\n\t\t\tif not ret:\n\t\t\t\tself.force_permissions()\n\t\t\treturn ret\n\n\t\tcode = self.inputs[0].read(encoding=getattr(self.generator, \'encoding\', \'latin-1\'))\n\t\tif getattr(self.generator, \'subst_fun\', None):\n\t\t\tcode = self.generator.subst_fun(self, code)\n\t\t\tif code is not None:\n\t\t\t\tself.outputs[0].write(code, encoding=getattr(self.generator, \'encoding\', \'latin-1\'))\n\t\t\tself.force_permissions()\n\t\t\treturn None\n\n\t\t# replace all % by %% to prevent errors by % signs\n\t\tcode = code.replace(\'%\', \'%%\')\n\n\t\t# extract the vars foo into lst and replace @foo@ by %(foo)s\n\t\tlst = []\n\t\tdef repl(match):\n\t\t\tg = match.group\n\t\t\tif g(1):\n\t\t\t\tlst.append(g(1))\n\t\t\t\treturn "%%(%s)s" % g(1)\n\t\t\treturn \'\'\n\t\tcode = getattr(self.generator, \'re_m4\', re_m4).sub(repl, code)\n\n\t\ttry:\n\t\t\td = self.generator.dct\n\t\texcept AttributeError:\n\t\t\td = {}\n\t\t\tfor x in lst:\n\t\t\t\ttmp = getattr(self.generator, x, \'\') or self.env[x] or self.env[x.upper()]\n\t\t\t\ttry:\n\t\t\t\t\ttmp = \'\'.join(tmp)\n\t\t\t\texcept TypeError:\n\t\t\t\t\ttmp = str(tmp)\n\t\t\t\td[x] = tmp\n\n\t\tcode = code % d\n\t\tself.outputs[0].write(code, encoding=getattr(self.generator, \'encoding\', \'latin-1\'))\n\t\tself.generator.bld.raw_deps[self.uid()] = lst\n\n\t\t# make sure the signature is updated\n\t\ttry:\n\t\t\tdelattr(self, \'cache_sig\')\n\t\texcept AttributeError:\n\t\t\tpass\n\n\t\tself.force_permissions()\n'

String representing an additional hash for the class representation

force_permissions()

Private for the time being, we will probably refactor this into run_str=[run1,chmod]

run()

Substitutes variables in a .in file

sig_vars()

Compute a hash (signature) of the variables used in the substitution

waflib.TaskGen.add_pcfile(self, node)

Processes .pc.in files to .pc. Installs the results to ${PREFIX}/lib/pkgconfig/ by default

def build(bld):

bld(source=’foo.pc.in’, install_path=’${LIBDIR}/pkgconfig/’)

class waflib.TaskGen.subst(*k, **kw)

hasrun

generator

env

waflib.ConfigSet.ConfigSet object (make sure to provide one)

inputs

List of input nodes, which represent the files used by the task instance

outputs

List of output nodes, which represent the files created by the task instance

dep_nodes

List of additional nodes to depend on

run_after

Set of tasks that must be executed before this one

hcode = b'\tdef run(self):\n\t\t"Substitutes variables in a .in file"\n\n\t\tif getattr(self.generator, \'is_copy\', None):\n\t\t\tfor i, x in enumerate(self.outputs):\n\t\t\t\tx.write(self.inputs[i].read(\'rb\'), \'wb\')\n\t\t\t\tstat = os.stat(self.inputs[i].abspath()) # Preserve mtime of the copy\n\t\t\t\tos.utime(self.outputs[i].abspath(), (stat.st_atime, stat.st_mtime))\n\t\t\tself.force_permissions()\n\t\t\treturn None\n\n\t\tif getattr(self.generator, \'fun\', None):\n\t\t\tret = self.generator.fun(self)\n\t\t\tif not ret:\n\t\t\t\tself.force_permissions()\n\t\t\treturn ret\n\n\t\tcode = self.inputs[0].read(encoding=getattr(self.generator, \'encoding\', \'latin-1\'))\n\t\tif getattr(self.generator, \'subst_fun\', None):\n\t\t\tcode = self.generator.subst_fun(self, code)\n\t\t\tif code is not None:\n\t\t\t\tself.outputs[0].write(code, encoding=getattr(self.generator, \'encoding\', \'latin-1\'))\n\t\t\tself.force_permissions()\n\t\t\treturn None\n\n\t\t# replace all % by %% to prevent errors by % signs\n\t\tcode = code.replace(\'%\', \'%%\')\n\n\t\t# extract the vars foo into lst and replace @foo@ by %(foo)s\n\t\tlst = []\n\t\tdef repl(match):\n\t\t\tg = match.group\n\t\t\tif g(1):\n\t\t\t\tlst.append(g(1))\n\t\t\t\treturn "%%(%s)s" % g(1)\n\t\t\treturn \'\'\n\t\tcode = getattr(self.generator, \'re_m4\', re_m4).sub(repl, code)\n\n\t\ttry:\n\t\t\td = self.generator.dct\n\t\texcept AttributeError:\n\t\t\td = {}\n\t\t\tfor x in lst:\n\t\t\t\ttmp = getattr(self.generator, x, \'\') or self.env[x] or self.env[x.upper()]\n\t\t\t\ttry:\n\t\t\t\t\ttmp = \'\'.join(tmp)\n\t\t\t\texcept TypeError:\n\t\t\t\t\ttmp = str(tmp)\n\t\t\t\td[x] = tmp\n\n\t\tcode = code % d\n\t\tself.outputs[0].write(code, encoding=getattr(self.generator, \'encoding\', \'latin-1\'))\n\t\tself.generator.bld.raw_deps[self.uid()] = lst\n\n\t\t# make sure the signature is updated\n\t\ttry:\n\t\t\tdelattr(self, \'cache_sig\')\n\t\texcept AttributeError:\n\t\t\tpass\n\n\t\tself.force_permissions()\n'

String representing an additional hash for the class representation

waflib.TaskGen.process_subst(self)

Task generator method

Defines a transformation that substitutes the contents of source files to target files:

def build(bld):
        bld(
                features='subst',
                source='foo.c.in',
                target='foo.c',
                install_path='${LIBDIR}/pkgconfig',
                VAR = 'val'
        )

The input files are supposed to contain macros of the form @VAR@, where VAR is an argument of the task generator object.

This method overrides the processing by waflib.TaskGen.process_source().

Feature

subst

Before

waflib.TaskGen.process_source(), waflib.TaskGen.process_rule()