Class ModuleVariableNode

A data flow node corresponding to a module-level (global) variable that is accessed outside of the module scope.

Global variables may appear twice in the data flow graph, as both EssaNodes and ModuleVariableNodes. The former is used to represent data flow between global variables as it occurs during module initialization, and the latter is used to represent data flow via global variable reads and writes during run-time.

It is possible for data to flow from assignments made at module initialization time to reads made at run-time, but not vice versa. For example, there will be flow from SOURCE to SINK in the following snippet:

g = SOURCE

def foo():
    SINK(g)

but not the other way round:

SINK(g)

def bar()
    global g
    g = SOURCE

Data flow through ModuleVariableNodes is represented as jumpSteps, and so any write of a global variable can flow to any read of the same variable.

Import path


                                import semmle.python.dataflow.new.internal.DataFlowPublic

Direct supertypes

Indirect supertypes

TNode

Fields

mod
var

Predicates

getADefiningWrite	Gets the possible values of the variable at the end of import time
getARead	Gets a node that reads this variable.
getAWrite	Gets an `EssaNode` that corresponds to an assignment of this global variable.
getEnclosingCallable	Gets the enclosing callable of this node.
getLocation	Gets the location of this node
getModule	Gets the module in which this variable appears.
getScope	Gets the scope of this node.
getVariable	Gets the global variable corresponding to this node.
toString	Gets a textual representation of this element.

Inherited predicates

asCfgNode	Gets the control-flow node corresponding to this node, if any.	from Node
asExpr	Gets the expression corresponding to this node, if any.	from Node
asVar	Gets the ESSA variable corresponding to this node, if any.	from Node
getALocalSource	Gets a local source node from which data may flow to this node in zero or more local data-flow steps.	from Node
hasLocationInfo	Holds if this element is at the specified location. The location spans column `startcolumn` of line `startline` to column `endcolumn` of line `endline` in file `filepath`. For more information, see Locations.	from Node

Charpred

ModuleVariableNode