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author | Guido van Rossum <guido@python.org> | 1995-03-17 16:07:09 (GMT) |
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committer | Guido van Rossum <guido@python.org> | 1995-03-17 16:07:09 (GMT) |
commit | 470be14c8aa23a35a1f4d1f1260a66a85d3f3cd9 (patch) | |
tree | 4fd0b8eda81e63366598e55362ceac85adafccb4 /Doc/libimp.tex | |
parent | 7760cdea81166b7741561043c58dae171811fb2f (diff) | |
download | cpython-470be14c8aa23a35a1f4d1f1260a66a85d3f3cd9.zip cpython-470be14c8aa23a35a1f4d1f1260a66a85d3f3cd9.tar.gz cpython-470be14c8aa23a35a1f4d1f1260a66a85d3f3cd9.tar.bz2 |
mass changes; fix titles; add examples; correct typos; clarifications;
unified style; etc.
Diffstat (limited to 'Doc/libimp.tex')
-rw-r--r-- | Doc/libimp.tex | 38 |
1 files changed, 16 insertions, 22 deletions
diff --git a/Doc/libimp.tex b/Doc/libimp.tex index 9ead176..91e250b 100644 --- a/Doc/libimp.tex +++ b/Doc/libimp.tex @@ -1,4 +1,4 @@ -\section{Built-in module \sectcode{imp}} +\section{Built-in Module \sectcode{imp}} \bimodindex{imp} \index{import} @@ -9,7 +9,7 @@ functions: \renewcommand{\indexsubitem}{(in module struct)} \begin{funcdesc}{get_magic}{} -Return the magic string used to recognize value byte-compiled code +Return the magic string value used to recognize byte-compiled code files (``\code{.pyc} files''). \end{funcdesc} @@ -22,15 +22,15 @@ string to pass to the built-in \code{open} function to open the file (this can be \code{'r'} for text files or \code{'rb'} for binary files), and \var{type} is the file type, which has one of the values \code{PY_SOURCE}, \code{PY_COMPILED} or \code{C_EXTENSION}, defined -below. +below. (System-dependent values may also be returned.) \end{funcdesc} \begin{funcdesc}{find_module}{name\, \optional{path}} Try to find the module \var{name} on the search path \var{path}. The default \var{path} is \code{sys.path}. The return value is a triple \code{(\var{file}, \var{pathname}, \var{description})} where -\var{file} is an open file object positioned at the beginning -corresponding to the file found, \var{pathname} is the pathname of the +\var{file} is an open file object positioned at the beginning, +\var{pathname} is the pathname of the file found, and \var{description} is a triple as contained in the list returned by \code{get_suffixes} describing the kind of file found. \end{funcdesc} @@ -134,33 +134,27 @@ The following function emulates the default import statement: \begin{verbatim} import imp -from sys import modules +import sys def __import__(name, globals=None, locals=None, fromlist=None): - # Fast path: let's see if it's already in sys.modules. - # Two speed optimizations are worth mentioning: - # - We use 'modules' instead of 'sys.modules'; this saves a - # dictionary look-up per call. - # - It's also faster to use a try-except statement than - # to use modules.has_key(name) to check if it's there. - try: - return modules[name] - except KeyError: - pass - - # See if it's a built-in module + # Fast path: see if the module has already been imported. + if sys.modules.has_key(name): + return sys.modules[name] + + # If any of the following calls raises an exception, + # there's a problem we con't handle -- let the caller handle it. + + # See if it's a built-in module. m = imp.init_builtin(name) if m: return m - # See if it's a frozen module + # See if it's a frozen module. m = imp.init_frozen(name) if m: return m # Search the default path (i.e. sys.path). - # If this raises an exception, the module is not found -- - # let the caller handle the exception. fp, pathname, (suffix, mode, type) = imp.find_module(name) # See what we got. @@ -170,7 +164,7 @@ def __import__(name, globals=None, locals=None, fromlist=None): if type == imp.PY_SOURCE: return imp.load_source(name, pathname, fp) if type == imp.PY_COMPILED: - return imp.load_source(name, pathname, fp) + return imp.load_compiled(name, pathname, fp) # Shouldn't get here at all. raise ImportError, '%s: unknown module type (%d)' % (name, type) |