On 10/27/2015 4:15 AM, Peter Otten wrote:
Terry Reedy wrote:
When one runs a
program with 'python somepath/file.py', python prepends somepath to
sys.path.
If /foo/bar contains a string.py (for example) module and you run the
following sequence
$ cd /foo/bar
$ python3 /usr/bin/idle3
I am curious what 'import sys; sys.path' prints in interactive mode, for
both 'python3' and the above, of whichever *nix you are running.
/foo/bar/string.py will shade string.py from the standard library.
Please reread what I wrote. IDLE is imitating Python. This shading the
same behavior as if you just typed $ python3. From
https://docs.python.org/3/library/sys.html#sys.path
"sys.path
A list of strings that specifies the search path for modules.
Initialized from the environment variable PYTHONPATH, plus an
installation-dependent default.
As initialized upon program startup, the first item of this list,
path[0], is the directory containing the script that was used to invoke
the Python interpreter. If the script directory is not available (e.g.
if the interpreter is invoked interactively or if the script is read
from standard input), path[0] is the empty string, which directs Python
to search modules in the current directory first. Notice that the script
directory is inserted before the entries inserted as a result of PYTHONPATH.
"
Modules in the current directory shade stdlib modules of the same name.
This is a feature for people who want this behavior. It is a problem
for people who are caught by it. The most common example here is
beginners who write their own random.py, for instance, and then another
file with 'import random', expecting to get the stdlib module. This has
nothing to do with IDLE. If you do not like this behavior, criticize
python, not IDLE.
"A program is free to modify this list for its own purposes."
IDLE's purpose is to imitate what python does, in both interactive and
batch modes. There are bugs relative to this (and I just opened
https://bugs.python.org/issue25488), but the bug is not 'imitating
python' but the failure to do so. If you find a non-trivial divergence
in how code is executed that I am not aware of, I would like to know.
The relevant code in idle is
https://hg.python.org/cpython/file/tip/Lib/idlelib/PyShell.py#l1522
"""
else:
dir = os.getcwd()
if dir not in sys.path:
sys.path.insert(0, dir)
"""
Nope, not in IDLE's normal mode, in which user code is executed in a
separate process. The above is for sys.process in the idle process. I
suspect it is a holdover from when Idle ran user code in its own process
(which is still does when -n is given on the command line).
In the previous line, before 'else', the directory of all files given as
args to be edited is added to sys.path. I suspect that this is to
enable completions in single process mode, which is deprecated.
I think this is a misfeature.
Why do you think it a misfeature for IDLE to execute code the way Python
does?
--
Terry Jan Reedy
--
https://mail.python.org/mailman/listinfo/python-list
