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SF patch #1438387, PEP 328: relative and absolute imports.

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- IMPORT_NAME takes an extra argument from the stack: the relativeness of
   the import. Only passed to __import__ when it's not -1.

 - __import__() takes an optional 5th argument for the same thing; it
   __defaults to -1 (old semantics: try relative, then absolute)

 - 'from . import name' imports name (be it module or regular attribute)
   from the current module's *package*. Likewise, 'from .module import name'
   will import name from a sibling to the current module.

 - Importing from outside a package is not allowed; 'from . import sys' in a
   toplevel module will not work, nor will 'from .. import sys' in a
   (single-level) package.

 - 'from __future__ import absolute_import' will turn on the new semantics
   for import and from-import: imports will be absolute, except for
   from-import with dots.

Includes tests for regular imports and importhooks, parser changes and a
NEWS item, but no compiler-package changes or documentation changes.
This commit is contained in:
Thomas Wouters 2006-02-28 16:09:29 +00:00
parent d3188639c3
commit f7f438ba3b
20 changed files with 270 additions and 73 deletions
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45
Python/ast.c
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@ -2171,9 +2171,8 @@ ast_for_import_stmt(struct compiling *c, const node *n)
/*
import_stmt: import_name | import_from
import_name: 'import' dotted_as_names
import_from: 'from' dotted_name 'import' ('*' |
'(' import_as_names ')' |
import_as_names)
import_from: 'from' ('.'* dotted_name | '.') 'import'
('*' | '(' import_as_names ')' | import_as_names)
*/
int i;
asdl_seq *aliases;
@ -2197,24 +2196,41 @@ ast_for_import_stmt(struct compiling *c, const node *n)
else if (TYPE(n) == import_from) {
int n_children;
int lineno = LINENO(n);
alias_ty mod = alias_for_import_name(c, CHILD(n, 1));
if (!mod)
return NULL;
switch (TYPE(CHILD(n, 3))) {
int idx, ndots = 0;
alias_ty mod = NULL;
identifier modname;
/* Count the number of dots (for relative imports) and check for the
optional module name */
for (idx = 1; idx < NCH(n); idx++) {
if (TYPE(CHILD(n, idx)) == dotted_name) {
mod = alias_for_import_name(c, CHILD(n, idx));
idx++;
break;
} else if (TYPE(CHILD(n, idx)) != DOT) {
break;
}
ndots++;
}
idx++; /* skip over the 'import' keyword */
switch (TYPE(CHILD(n, idx))) {
case STAR:
/* from ... import * */
n = CHILD(n, 3);
n = CHILD(n, idx);
n_children = 1;
if (ndots) {
ast_error(n, "'import *' not allowed with 'from .'");
return NULL;
}
break;
case LPAR:
/* from ... import (x, y, z) */
n = CHILD(n, 4);
n = CHILD(n, idx + 1);
n_children = NCH(n);
break;
case import_as_names:
/* from ... import x, y, z */
n = CHILD(n, 3);
n = CHILD(n, idx);
n_children = NCH(n);
if (n_children % 2 == 0) {
ast_error(n, "trailing comma not allowed without"
@ -2245,7 +2261,12 @@ ast_for_import_stmt(struct compiling *c, const node *n)
return NULL;
asdl_seq_APPEND(aliases, import_alias);
}
return ImportFrom(mod->name, aliases, lineno, c->c_arena);
if (mod != NULL)
modname = mod->name;
else
modname = new_identifier("", c->c_arena);
return ImportFrom(modname, aliases, ndots, lineno,
c->c_arena);
}
PyErr_Format(PyExc_SystemError,
"unknown import statement: starts with command '%s'",