org.python.indexer.ast

Class NImportFrom

java.lang.Object

org.python.indexer.ast.NNode

org.python.indexer.ast.NImportFrom

All Implemented Interfaces:

java.io.Serializable

public class NImportFrom
extends NNode

Handles import from statements such as from moduleA import a, b as c, d and from foo.bar.moduleB import *.

The indexer's implementation of import * uses different semantics from all the other forms of import. It's basically a bug, although the jury is still out as to which implementation is better.

For the others we define name bindings anywhere an actual name is introduced into the scope containing the import statement, and references to the imported module or name everywhere else. This mimics the behavior of Python at runtime, but it may be confusing to anyone with only a casual understanding of Python's data model, who might think it works more like Java.

For import * we just enter the imported names into the symbol table, which lets other code reference them, but the references "pass through" automatically to the module from which the names were imported.

To illustate the difference, consider the following four modules:

  moduleA.py:
     a = 1
     b = 2

  moduleB.py:
     c = 3
     d = 4

  moduleC.py:
     from moduleA import a, b
     from moduleB import *
     print a  # indexer finds definition of 'a' 2 lines up
     print b  # indexer finds definition of 'b' 3 lines up
     print c  # indexer finds definition of 'c' in moduleB
     print d  # indexer finds definition of 'd' in moduleB

  moduleD.py:
     import moduleC
     print moduleC.a  # indexer finds definition of 'a' in moduleC
     print moduleC.b  # indexer finds definition of 'b' in moduleC
     print moduleC.c  # indexer finds definition of 'c' in moduleB
     print moduleC.c  # indexer finds definition of 'd' in moduleB
 

To make import * work like the others, we need only create bindings for the imported names. But where would the bindings be located? Assuming that we were to co-locate them all at the "*" name node, clicking on a reference to any of the names would jump to the "*". It's not clear that this is a better user experience.

We could make the other import statement forms work like import *, but that path is even more fraught with confusing inconsistencies.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
java.util.List<NAlias>	aliases
java.lang.String	module
NQname	qname

Constructor Summary

Constructors

Constructor and Description
NImportFrom(java.lang.String module, NQname qname, java.util.List<NAlias> aliases)
NImportFrom(java.lang.String module, NQname qname, java.util.List<NAlias> aliases, int start, int end)

Method Summary

Modifier and Type	Method and Description
boolean	bindsName() Returns true if this is a name-binding node.
boolean	isImportStar()
NType	resolve(Scope s) Node should set the resolved type in its NNode.type field and also return it.
java.lang.String	toString()
void	visit(NNodeVisitor v) Visits this node and optionally its children.

Methods inherited from class org.python.indexer.ast.NNode

addChildren, addChildren, addType, end, getAstRoot, getDeepestNodeAtOffset, getEnclosingNamespace, getFile, getParent, getTable, getType, isCall, isClassDef, isFunctionDef, isLambda, isModule, isName, length, resolveExpr, setEnd, setParent, setStart, setType, start

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

module

public java.lang.String module

qname

public NQname qname

aliases

public java.util.List<NAlias> aliases

Constructor Detail

NImportFrom

public NImportFrom(java.lang.String module,
                   NQname qname,
                   java.util.List<NAlias> aliases)

NImportFrom

public NImportFrom(java.lang.String module,
                   NQname qname,
                   java.util.List<NAlias> aliases,
                   int start,
                   int end)

Method Detail

bindsName

public boolean bindsName()

Description copied from class: NNode

Returns true if this is a name-binding node. Includes functions/lambdas, function/lambda params, classes, assignments, imports, and implicit assignment via for statements and except clauses.

Overrides:

bindsName in class NNode

See Also:

PEP 227

resolve

public NType resolve(Scope s)
              throws java.lang.Exception

Description copied from class: NNode

Node should set the resolved type in its NNode.type field and also return it.

Overrides:

resolve in class NNode

Throws:

java.lang.Exception

isImportStar

public boolean isImportStar()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

visit

public void visit(NNodeVisitor v)

Description copied from class: NNode

Visits this node and optionally its children.

Specified by:

visit in class NNode

Parameters:

v - the object to call with this node. If the visitor returns true, the node also passes its children to the visitor.