Task

Tasks represent atomic operations such as processes.

waflib.Task.NOT_RUN = 0

The task was not executed yet

waflib.Task.MISSING = 1

The task has been executed but the files have not been created

waflib.Task.CRASHED = 2

The task execution returned a non-zero exit status

waflib.Task.EXCEPTION = 3

An exception occurred in the task execution

waflib.Task.SKIPPED = 8

The task did not have to be executed

waflib.Task.SUCCESS = 9

The task was successfully executed

waflib.Task.ASK_LATER = -1

The task is not ready to be executed

waflib.Task.SKIP_ME = -2

The task does not need to be executed

waflib.Task.RUN_ME = -3

The task must be executed

waflib.Task.classes = {'pdflatex': <class 'waflib.Tools.tex.pdflatex'>, 'glib_validate_schema': <class 'waflib.Tools.glib2.glib_validate_schema'>, 'JTask': <class 'waflib.Tools.javaw.JTask'>, 'javac': <class 'waflib.Tools.javaw.javac'>, 'cxx': <class 'waflib.Tools.cxx.cxx'>, 'glib_gresource_base': <class 'waflib.Tools.glib2.glib_gresource_base'>, 'cxxshlib': <class 'waflib.Tools.cxx.cxxshlib'>, 'valac': <class 'waflib.Tools.vala.valac'>, 'javadoc': <class 'waflib.Tools.javaw.javadoc'>, 'fcstlib': <class 'waflib.Tools.fc.fcstlib'>, 'd_with_header': <class 'waflib.Tools.d.d_with_header'>, 'fake_csshlib': <class 'waflib.Tools.cs.fake_csshlib'>, 'glib_gresource_source': <class 'waflib.Tools.glib2.glib_gresource_source'>, 'xelatex': <class 'waflib.Tools.tex.xelatex'>, 'dbus_binding_tool': <class 'waflib.Tools.dbus.dbus_binding_tool'>, 'fake_o': <class 'waflib.Tools.ccroot.fake_o'>, 'd_header': <class 'waflib.Tools.d.d_header'>, 'fcshlib': <class 'waflib.Tools.fc.fcshlib'>, 'macplist': <class 'waflib.Tools.c_osx.macplist'>, 'grep_for_endianness': <class 'waflib.Tools.c_tests.grep_for_endianness'>, 'dvipdf': <class 'waflib.Tools.tex.dvipdf'>, 'winrc': <class 'waflib.Tools.winres.winrc'>, 'intltool': <class 'waflib.Tools.intltool.intltool'>, 'asmstlib': <class 'waflib.Tools.asm.asmstlib'>, 'trans_update': <class 'waflib.Tools.qt5.trans_update'>, 'asmshlib': <class 'waflib.Tools.asm.asmshlib'>, 'c': <class 'waflib.Tools.c.c'>, 'glib_genmarshal': <class 'waflib.Tools.glib2.glib_genmarshal'>, 'utest': <class 'waflib.Tools.waf_unit_test.utest'>, 'fcprogram': <class 'waflib.Tools.fc.fcprogram'>, 'subst': <class 'waflib.TaskGen.subst'>, 'glib_mkenums': <class 'waflib.Tools.glib2.glib_mkenums'>, 'cxxprogram': <class 'waflib.Tools.cxx.cxxprogram'>, 'stlink_task': <class 'waflib.Tools.ccroot.stlink_task'>, 'bison': <class 'waflib.Tools.bison.bison'>, 'glib_gresource_bundle': <class 'waflib.Tools.glib2.glib_gresource_bundle'>, 'cshlib': <class 'waflib.Tools.c.cshlib'>, 'rcc': <class 'waflib.Tools.qt5.rcc'>, 'flex': <class 'waflib.Task.flex'>, 'Task': <class 'waflib.Task.Task'>, 'latex': <class 'waflib.Tools.tex.latex'>, 'ts2qm': <class 'waflib.Tools.qt5.ts2qm'>, 'run_ruby': <class 'waflib.Tools.ruby.run_ruby'>, 'cprogram': <class 'waflib.Tools.c.cprogram'>, 'xsubpp': <class 'waflib.Tools.perl.xsubpp'>, 'fc': <class 'waflib.Tools.fc.fc'>, 'inst': <class 'waflib.Build.inst'>, 'po': <class 'waflib.Tools.intltool.po'>, 'pyo': <class 'waflib.Tools.python.pyo'>, 'moc': <class 'waflib.Tools.qt5.moc'>, 'pdf2ps': <class 'waflib.Tools.tex.pdf2ps'>, 'vnum': <class 'waflib.Tools.ccroot.vnum'>, 'pyc': <class 'waflib.Tools.python.pyc'>, 'mcs': <class 'waflib.Tools.cs.mcs'>, 'asm': <class 'waflib.Tools.asm.asm'>, 'd': <class 'waflib.Tools.d.d'>, 'dstlib': <class 'waflib.Tools.d.dstlib'>, 'test_exec': <class 'waflib.Tools.c_config.test_exec'>, 'fake_shlib': <class 'waflib.Tools.ccroot.fake_shlib'>, 'macapp': <class 'waflib.Tools.c_osx.macapp'>, 'link_task': <class 'waflib.Tools.ccroot.link_task'>, 'cfgtask': <class 'waflib.Tools.c_config.cfgtask'>, 'asmprogram': <class 'waflib.Tools.asm.asmprogram'>, 'tex': <class 'waflib.Tools.tex.tex'>, 'jar_create': <class 'waflib.Tools.javaw.jar_create'>, 'cxxstlib': <class 'waflib.Tools.cxx.cxxstlib'>, 'dprogram': <class 'waflib.Tools.d.dprogram'>, 'subst_pc': <class 'waflib.TaskGen.subst_pc'>, 'qm2rcc': <class 'waflib.Tools.qt5.qm2rcc'>, 'dshlib': <class 'waflib.Tools.d.dshlib'>, 'dvips': <class 'waflib.Tools.tex.dvips'>, 'cstlib': <class 'waflib.Tools.c.cstlib'>, 'ui5': <class 'waflib.Tools.qt5.ui5'>, 'qxx': <class 'waflib.Tools.qt5.qxx'>, 'luac': <class 'waflib.Tools.lua.luac'>, 'fcprogram_test': <class 'waflib.Tools.fc.fcprogram_test'>, 'fake_stlib': <class 'waflib.Tools.ccroot.fake_stlib'>}

The metaclass waflib.Task.store_task_type stores all class tasks created by user scripts or Waf tools to this dict. It maps class names to class objects.

class waflib.Task.store_task_type(name, bases, dict)

Bases: type

Metaclass: store the task classes into the dict pointed by the class attribute ‘register’ which defaults to waflib.Task.classes,

The attribute ‘run_str’ is compiled into a method ‘run’ bound to the task class.

class waflib.Task.evil

Bases: object

Base class provided to avoid writing a metaclass, so the code can run in python 2.6 and 3.x unmodified

class waflib.Task.TaskBase(*k, **kw)

Bases: waflib.Task.evil

Base class for all Waf tasks, which should be seen as an interface. For illustration purposes, instances of this class will execute the attribute ‘fun’ in waflib.Task.TaskBase.run(). When in doubt, create subclasses of waflib.Task.Task instead.

Subclasses must override these methods:

1. __str__: string to display to the user
2. runnable_status: ask the task if it should be run, skipped, or if we have to ask later
3. run: what to do to execute the task
4. post_run: what to do after the task has been executed

color = 'GREEN'

Color for the console display, see waflib.Logs.colors_lst

ext_in = []

File extensions that objects of this task class may use

ext_out = []

File extensions that objects of this task class may create

before = []

List of task class names to execute before instances of this class

after = []

List of task class names to execute after instances of this class

hcode = ''

String representing an additional hash for the class representation

keep_last_cmd = False

Whether to keep the last command executed on the instance after execution. This may be useful for certain extensions but it can a lot of memory.

__slots__ = ('hasrun', 'generator')

__init__(*k, **kw)

The base task class requires a task generator (set to self if missing)

__str__()

String to display to the user

keyword()

Display keyword used to prettify the console outputs

get_cwd()

Returns:current working directory Return type:waflib.Node.Node

quote_flag(x)

Surround a process argument by quotes so that a list of arguments can be written to a file

Parameters:x (string) – flag Returns:quoted flag Return type:string

split_argfile(cmd)

Splits a list of process commands into the executable part and its list of arguments

Returns:a tuple containing the executable first and then the rest of arguments Return type:tuple

exec_command(cmd, **kw)

Wrapper for waflib.Context.Context.exec_command(). This version set the current working directory (build.variant_dir), applies PATH settings (if self.env.PATH is provided), and can run long commands through a temporary @argfile.

Parameters:cmd (list of string (best) or string (process will use a shell)) – process command to execute Returns:the return code Return type:int

runnable_status()

Returns the Task status

Returns:a task state in waflib.Task.RUN_ME, waflib.Task.SKIP_ME or waflib.Task.ASK_LATER. Return type:int

uid()

Computes a unique identifier for the task

Return type:string or bytes

run()

Called by threads to execute the tasks. The default is empty and meant to be overridden in subclasses.

Warning

It is a bad idea to create nodes in this method, so avoid waflib.Node.Node.ant_glob()

Return type:int

post_run()

Update build data after successful Task execution. Override in subclasses.

log_display(bld)

Writes the execution status on the context logger

display()

Returns an execution status for the console, the progress bar, or the IDE output.

Return type:string

hash_constraints()

Identifies a task type for all the constraints relevant for the scheduler: precedence, file production

Returns:a hash value Return type:string

format_error()

Returns an error message to display the build failure reasons

Return type:string

colon(var1, var2)

Enable scriptlet expressions of the form ${FOO_ST:FOO} If the first variable (FOO_ST) is empty, then an empty list is returned

The results will be slightly different if FOO_ST is a list, for example:

env.FOO_ST = ['-a', '-b']
env.FOO_ST = '-I%s'
# ${FOO_ST:FOO} returns
['-Ip1', '-Ip2']

env.FOO    = ['p1', 'p2']
# ${FOO_ST:FOO} returns
['-a', '-b', 'p1', '-a', '-b', 'p2']

class waflib.Task.Task(*k, **kw)

Bases: waflib.Task.TaskBase

This class deals with the filesystem (waflib.Node.Node). The method waflib.Task.Task.runnable_status uses a hash value (from waflib.Task.Task.signature) which is persistent from build to build. When the value changes, the task has to be executed. The method waflib.Task.Task.post_run will assign the task signature to the output nodes (if present).

vars = []

ConfigSet variables that should trigger a rebuild (class attribute used for waflib.Task.Task.sig_vars())

always_run = False

Specify whether task instances must always be executed or not (class attribute)

shell = False

Execute the command with the shell (class attribute)

env = None

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

inputs = None

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

outputs = None

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

dep_nodes = None

List of additional nodes to depend on

run_after = None

Set of tasks that must be executed before this one

__str__()

string to display to the user

keyword()

See waflib.Task.TaskBase()

__repr__()

for debugging purposes

uid()

Returns an identifier used to determine if tasks are up-to-date. Since the identifier will be stored between executions, it must be:

• unique for a task: no two tasks return the same value (for a given build context)
• the same for a given task instance

By default, the node paths, the class name, and the function are used as inputs to compute a hash.

The pointer to the object (python built-in ‘id’) will change between build executions, and must be avoided in such hashes.

Returns:hash value Return type:string

hcode = '\tdef run(self):\n\t\t"""\n\t\tCalled by threads to execute the tasks. The default is empty and meant to be overridden in subclasses.\n\n\t\t.. warning:: It is a bad idea to create nodes in this method, so avoid :py:meth:`waflib.Node.Node.ant_glob`\n\n\t\t:rtype: int\n\t\t"""\n\t\tif hasattr(self, \'fun\'):\n\t\t\treturn self.fun(self)\n\t\treturn 0\n'

set_inputs(inp)

Appends the nodes to the inputs list

Parameters:inp (node or list of nodes) – input nodes

set_outputs(out)

Appends the nodes to the outputs list

Parameters:out (node or list of nodes) – output nodes

set_run_after(task)

Run this task only after the given task.

Parameters:task (waflib.Task.Task) – task

signature()

Task signatures are stored between build executions, they are use to track the changes made to the input nodes (not to the outputs!). The signature hashes data from various sources:

• explicit dependencies: files listed in the inputs (list of node objects) waflib.Task.Task.sig_explicit_deps()
• implicit dependencies: list of nodes returned by scanner methods (when present) waflib.Task.Task.sig_implicit_deps()
• hashed data: variables/values read from task.vars/task.env waflib.Task.Task.sig_vars()

If the signature is expected to give a different result, clear the cache kept in self.cache_sig:

from waflib import Task
class cls(Task.Task):
        def signature(self):
                sig = super(Task.Task, self).signature()
                delattr(self, 'cache_sig')
                return super(Task.Task, self).signature()

Returns:the signature value Return type:string or bytes

runnable_status()

See waflib.Task.TaskBase.runnable_status()

post_run()

Update the cache files (executed by threads). Override in subclasses.

sig_explicit_deps()

Used by waflib.Task.Task.signature(); it hashes waflib.Task.Task.inputs and waflib.Task.Task.dep_nodes signatures.

sig_vars()

Used by waflib.Task.Task.signature(); it hashes waflib.Task.Task.env variables/values

scan = None

This method, when provided, returns a tuple containing:

• a list of nodes corresponding to real files
• a list of names for files not found in path_lst

For example:

from waflib.Task import Task
class mytask(Task):
        def scan(self, node):
                return ([], [])

The first and second lists in the tuple are stored in waflib.Build.BuildContext.node_deps and waflib.Build.BuildContext.raw_deps respectively.

sig_implicit_deps()

Used by waflib.Task.Task.signature(); it hashes node signatures obtained by scanning for dependencies (waflib.Task.Task.scan()).

The exception waflib.Errors.TaskRescan is thrown when a file has changed. In this case, the method waflib.Task.Task.signature() is called once again, and return here to call waflib.Task.Task.scan() and searching for dependencies.

compute_sig_implicit_deps()

Used by waflib.Task.Task.sig_implicit_deps() for computing the actual hash of the waflib.Node.Node returned by the scanner.

Returns:a hash value for the implicit dependencies Return type:string or bytes

are_implicit_nodes_ready()

For each node returned by the scanner, see if there is a task that creates it, and infer the build order

This has a low performance impact on null builds (1.86s->1.66s) thanks to caching (28s->1.86s)

waflib.Task.is_before(t1, t2)

Returns a non-zero value if task t1 is to be executed before task t2:

t1.ext_out = '.h'
t2.ext_in = '.h'
t2.after = ['t1']
t1.before = ['t2']
waflib.Task.is_before(t1, t2) # True

Parameters:

• t1 (waflib.Task.TaskBase) – Task object
• t2 (waflib.Task.TaskBase) – Task object

waflib.Task.set_file_constraints(tasks)

Updates the run_after attribute of all tasks based on the task inputs and outputs

Parameters:tasks (list of waflib.Task.TaskBase) – tasks

waflib.Task.set_precedence_constraints(tasks)

Updates the run_after attribute of all tasks based on the after/before/ext_out/ext_in attributes

Parameters:tasks (list of waflib.Task.TaskBase) – tasks

waflib.Task.funex(c)

Compiles a scriptlet expression into a Python function

Parameters:c (string) – function to compile Returns:the function ‘f’ declared in the input string Return type:function

waflib.Task.compile_fun_shell(line)

Creates a compiled function to execute a process through a sub-shell

waflib.Task.compile_fun_noshell(line)

Creates a compiled function to execute a process without a sub-shell

waflib.Task.compile_fun(line, shell=False)

Parses a string expression such as ‘${CC} ${SRC} -o ${TGT}’ and returns a pair containing:

• The function created (compiled) for use as waflib.Task.TaskBase.run()
• The list of variables that must cause rebuilds when env data is modified

for example:

from waflib.Task import compile_fun
compile_fun('cxx', '${CXX} -o ${TGT[0]} ${SRC} -I ${SRC[0].parent.bldpath()}')

def build(bld):
        bld(source='wscript', rule='echo "foo\${SRC[0].name}\bar"')

The env variables (CXX, ..) on the task must not hold dicts so as to preserve a consistent order. The reserved keywords TGT and SRC represent the task input and output nodes

waflib.Task.task_factory(name, func=None, vars=None, color='GREEN', ext_in=[], ext_out=[], before=[], after=[], shell=False, scan=None)

Returns a new task subclass with the function run compiled from the line given.

Parameters:

• func (string or function) – method run
• vars (list of string) – list of variables to hash
• color (string) – color to use
• shell (bool) – when func is a string, enable/disable the use of the shell
• scan (function) – method scan

Return type:

waflib.Task.Task

waflib.Task.always_run(cls)

Deprecated Task class decorator (to be removed in waf 2.0)

Set all task instances of this class to be executed whenever a build is started The task signature is calculated, but the result of the comparison between task signatures is bypassed

waflib.Task.update_outputs(cls)

Obsolete, to be removed in waf 2.0