Package SCons :: Package Node :: Module Python :: Class Value

Class Value

Node --+
       |
      Value

A class for Python variables, typically passed on the command line or generated by a script, but not from a file or some other source.

Nested Classes

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NodeInfo
The generic base class for signature information for a Node.

BuildInfo
The generic base class for build information for a Node.

Inherited from Node: Attrs

Instance Methods

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__init__(self, value, built_value=False)

source code

str_for_display(self)

source code

__str__(self)

source code

make_ready(self)
Get a Node ready for evaluation.

source code

build(self, **kw)
Actually build the node.

source code

is_up_to_date(self)
Alternate check for whether the Node is current: If all of our children were up-to-date, then this Node was up-to-date, too.

source code

is_under(self, dir)

source code

write(self, built_value)
Set the value of the node.

source code

read(self)
Return the value.

source code

get_contents(self)
By the assumption that the node.built_value is a deterministic product of the sources, the contents of a Value are the concatenation of all the contents of its sources.

source code

changed_since_last_build(self, target, prev_ni)
Must be overridden in a specific subclass to return True if this Node (a dependency) has changed since the last time it was used to build the specified target.

source code

get_csig(self, calc=False)
Because we're a Python value node and don't have a real timestamp, we get to ignore the calculator and just use the value contents.

source code

Inherited from Node: Decider, add_dependency, add_ignore, add_prerequisite, add_source, add_to_implicit, add_to_waiting_parents, add_to_waiting_s_e, add_wkid, all_children, alter_targets, builder_set, built, changed, children, children_are_up_to_date, clear, clear_memoized_values, del_binfo, disambiguate, do_not_store_info, env_set, executor_cleanup, exists, explain, for_signature, get_abspath, get_binfo, get_build_env, get_build_scanner_path, get_builder, get_cachedir_csig, get_env, get_env_scanner, get_executor, get_found_includes, get_implicit_deps, get_ninfo, get_source_scanner, get_state, get_stored_implicit, get_stored_info, get_string, get_subst_proxy, get_suffix, get_target_scanner, has_builder, has_explicit_builder, is_derived, is_literal, missing, multiple_side_effect_has_builder, new_binfo, new_ninfo, postprocess, prepare, remove, render_include_tree, reset_executor, retrieve_from_cache, rexists, scan, scanner_key, select_scanner, set_always_build, set_executor, set_explicit, set_nocache, set_noclean, set_precious, set_specific_source, set_state, state_has_changed, store_info, visited

Inherited from Node (private): _add_child, _children_get, _children_reset

Class Variables

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Inherited from Node: __metaclass__, memoizer_counters

Method Details

[hide private]

init(self, value, built_value=False)
(Constructor)

source code

Overrides: Node.__init__

make_ready(self)

source code

Get a Node ready for evaluation.

This is called before the Taskmaster decides if the Node is up-to-date or not. Overriding this method allows for a Node subclass to be disambiguated if necessary, or for an implicit source builder to be attached.

Overrides: Node.make_ready: (inherited documentation)

build(self, **kw)

source code

Actually build the node.

This is called by the Taskmaster after it's decided that the Node is out-of-date and must be rebuilt, and after the prepare() method has gotten everything, uh, prepared.

This method is called from multiple threads in a parallel build, so only do thread safe stuff here. Do thread unsafe stuff in built().

Overrides: Node.build: (inherited documentation)

is_up_to_date(self)

source code

Alternate check for whether the Node is current: If all of our children were up-to-date, then this Node was up-to-date, too.

The SCons.Node.Alias and SCons.Node.Python.Value subclasses rebind their current() method to this method.

Overrides: Node.is_up_to_date

read(self)

source code

Return the value. If necessary, the value is built.

get_contents(self)

source code

By the assumption that the node.built_value is a deterministic product of the sources, the contents of a Value are the concatenation of all the contents of its sources. As the value need not be built when get_contents() is called, we cannot use the actual node.built_value.

changed_since_last_build(self, target, prev_ni)

source code

Must be overridden in a specific subclass to return True if this Node (a dependency) has changed since the last time it was used to build the specified target. prev_ni is this Node's state (for example, its file timestamp, length, maybe content signature) as of the last time the target was built.

Note that this method is called through the dependency, not the target, because a dependency Node must be able to use its own logic to decide if it changed. For example, File Nodes need to obey if we're configured to use timestamps, but Python Value Nodes never use timestamps and always use the content. If this method were called through the target, then each Node's implementation of this method would have to have more complicated logic to handle all the different Node types on which it might depend.

Overrides: Node.changed_since_last_build: (inherited documentation)

get_csig(self, calc=False)

source code

Because we're a Python value node and don't have a real timestamp, we get to ignore the calculator and just use the value contents.

Overrides: Node.get_csig

Class Value

__init__(self, value, built_value=False) (Constructor)

make_ready(self)

build(self, **kw)

is_up_to_date(self)

read(self)

get_contents(self)

changed_since_last_build(self, target, prev_ni)

get_csig(self, calc=False)

init(self, value, built_value=False)
(Constructor)