Apply PEP 441 changes from Paul Moore

pep-0441.txt

@@ -73,6 +73,7 @@ concatenated to the end of any other file.  This feature is completely
 standard and is how self-extracting ZIP archives and the bdist_wininst
 installer format work.
 
+
 Minimal Tooling: The zipapp Module
 ==================================
 
@@ -82,47 +83,75 @@ zip application archives, and a command line interface (via ``python
 -m zipapp``) for their creation and manipulation.
 
 More complete tools for managing Python Zip Applications are
-encouraged as 3rd party applications on PyPI.  Currently, pyyzer [5]_
-and pex [6]_ are two tools known to exist.
+encouraged as 3rd party applications on PyPI.  Currently, pyzzer [5]_
+and pex [6]_ are two such tools.
 
 Module Interface
 ----------------
 
 The zipapp module will provide the following functions:
 
-``pack(directory, target=None, interpreter=None, main=None)``
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+``create_archive(source, target=None, interpreter=None, main=None)``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-Writes an application archive called *target*, containing the contents
-of *directory*.  The *target* can be a filename, or a file-like object
-(which must be open for writing in bytes mode), or None (which means
-use the name of *directory* with ``.pyz`` appended).  If *interpreter*
-is specified, it will be written to the start of the archive as a
-shebang line and the file will be made executable (if no interpreter
-is specified, the shebang line will be omitted).  If the directory
-contains no ``__main__.py`` file, the function will construct a
-``__main__.py`` which calls the function specified in the *main*
-argument (which should be in the form ``'pkg.mod:fn'``).
+Create an application archive from *source*.  The source can be any
+of the following:
 
-It is an error to specify *main* if the directory contains a
-``__main__.py``, or to omit *main* when there is no ``__main__.py``
-(as that will result in an archive which has no main function and so
-cannot be executed).
+* The name of a directory, in which case a new application archive
+  will be created from the content of that directory.
+* The name of an existing application archive file, in which case the
+  file is copied to the target.  The file name should include the
+  ``.pyz`` extension, if required.
+* A file object open for reading in bytes mode.  The content of the
+  file should be an application archive, and the file object is
+  assumed to be positioned at the start of the archive.
+
+The *target* argument determines where the resulting archive will be
+written:
+
+* If it is the name of a file, the archive will be written to that
+  file.
+* If it is an open file object, the archive will be written to that
+  file object, which must be open for writing in bytes mode.
+* If the target is omitted (or None), the source must be a directory
+  and the target will be a file with the same name as the source, with
+  a ``.pyz`` extension added.
+
+The *interpreter* argument specifies the name of the Python
+interpreter with which the archive will be executed.  It is written as
+a "shebang" line at the start of the archive.  On Unix, this will be
+interpreted by the OS, and on Windows it will be handled by the Python
+launcher.  Omitting the *interpreter* results in no shebang line being
+written.  If an interpreter is specified, and the target is a
+filename, the executable bit of the target file will be set.
+
+The *main* argument specifies the name of a callable which will be
+used as the main program for the archive.  It can only be specified if
+the source is a directory, and the source does not already contain a
+``__main__.py`` file.  The *main* argument should take the form
+"pkg.module:callable" and the archive will be run by importing
+"pkg.module" and executing the given callable with no arguments.  It
+is an error to omit *main* if the source is a directory and does not
+contain a ``__main__.py`` file, as otherwise the resulting archive
+would not be executable.
+
+If a file object is specified for *source* or *target*, it is the
+caller's responsibility to close it after calling create_archive.
+
+When copying an existing archive, file objects supplied only need
+``read`` and ``readline``, or ``write`` methods.  When creating an
+archive from a directory, if the target is a file object it will be
+passed to the ``zipfile.ZipFile`` class, and must supply the methods
+needed by that class.
 
 ``get_interpreter(archive)``
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-Returns the interpreter specified in the shebang line of the *archive*.
-If there is no shebang, the function returns ``None``.
+Returns the interpreter specified in the shebang line of the
+*archive*.  If there is no shebang, the function returns ``None``.
+The *archive* argument can be a filename or a file-like object open
+for reading in bytes mode.
 
-``set_interpreter(archive, new_archive, interpreter=None)``
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Modifies the *archive*'s shebang line to contain the specified
-interpreter, and writes the updated archive to *new_archive*.  If the
-*interpreter* is ``None``, removes the shebang line.  The
-*new_archive* argument can be a filename, or a file-like object open
-for writing in byte mode.
 
 Command Line Usage
 ------------------
@@ -130,17 +159,20 @@ Command Line Usage
 The zipapp module can be run with the python ``-m`` flag.  The command
 line interface is as follows::
 
-    python -m zipapp [options] directory
+    python -m zipapp directory [options]
 
-        Create an archive from the contents of the given directory. By
-        default, an archive will be created with the same name as the
-        source directory, with a .pyz extension.
+        Create an archive from the given directory.  An archive will
+        be created from the contents of that directory.  The archive
+        will have the same name as the source directory with a .pyz
+        extension.
 
         The following options can be specified:
 
         -o archive / --output archive
 
-            The destination archive will have the specified name.
+            The destination archive will have the specified name.  The
+            given name will be used as written, so should include the
+            ".pyz" extension.
 
         -p interpreter / --python interpreter
 
@@ -155,10 +187,36 @@ line interface is as follows::
             which calls fn from the module pkg.mod.
 
 The behaviour of the command line interface matches that of
-``zipapp.pack()``.
+``zipapp.create_archive()``.
+
+In addition, it is possible to use the command line interface to work
+with an existing archive::
+
+    python -m zipapp app.pyz --show
+
+        Displays the shebang line of an archive.  Output is of the
+        form
+
+            Interpreter: /usr/bin/env
+        or
+            Interpreter: <none>
+
+        and is intended for diagnostic use, not for scripts.
+
+    python -m zipapp app.pyz -o newapp.pyz [-p interpreter]
+
+        Copy app.pyz to newapp.pyz, modifying the shebang line based
+        on the -p option (as for creating an archive, no -p option
+        means remove the shebang line).  Specifying a destination is
+        mandatory.
+
+        In-place modification of an archive is *not* supported, as the
+        risk of damaging archives is too great for a simple tool.
 
 As noted, the archives are standard zip files, and so can be unpacked
-using any standard ZIP utility or Python's zipfile module.
+using any standard ZIP utility or Python's zipfile module.  For this
+reason, no interfaces to list the contents of an archive, or unpack
+them, are provided or needed.
 
 FAQ
 ---