On 3/6/2016 7:24 AM, alien2u...@gmail.com wrote:
Hello list,
I am following "Learning Python: Mark Lutz" and came across following
in chapter 3 few days back.
What is the copyright date on the copy you have?
[quote] * You may still have to reload nested modules. Technically
speaking, IDLE's Run->Run Module menu option always runs the current
version of the top-level file only; imported files may still need to
be interactively reloaded when changed. ... [/quote]
It is slightly confusing, as to what it does imply. Could any IDLE
guru clarify if I am missing or overlooking something?
IDLE currently, in its default mode, runs a module in a fresh separate
process with a fresh sys.modules. It closely simulates running a module
from the command line with 'python -m mymodule'. (One difference is
that sys.modules is initially larger when run by IDLE.)
The quoted statement must have been written when IDLE always ran user
code in the persistent IDLE process, as it still does if one starts IDLE
with the -n option. The current IDLE doc, in section 3.3. 'Running
without a subprocess' (with -n) ends with
"Also, the environment is not restarted when Run/Run Module (F5) is
selected. If your code has been modified, you must reload() the
affected modules and re-import any specific items (e.g. from foo import
baz) if the changes are to take effect. For these reasons, it is
preferable to run IDLE with the default subprocess if at all possible."
Even if there were an attempt to restore sys.modules on F5, the comment
would still apply if one edited and saved an stdlib module imported by
IDLE. I run into this when I edit an idlelib file. I can run tests on
the file in a separate process with F5, but to verify that the edit has
the intended effect on IDLE itself, I have to restart IDLE itself.
If the quoted statement is in the most recent version of the book, it
should be changed in the next one.
If a needed-by-top-level-file module was changed after 'Run->Run
Module', it would any way need to be reloaded.
If it was changed between two "Run->Run Module" actions, won't it be
automatically loaded afresh as a part of restarting Python
interpreter and executing top-level-file [where is the question of
reloading then?]?
[Side observation: though F5 or "Run->Run Module" restarts Python
interpreter with top-level-file afresh [indicated by dir() content
before and after], the command history is not reset during this.
Commands are entered into and kept in the Shell in the IDLE process.
There are not erased unless one closes Shell. If there is an editor
window that keeps IDLE running, and one hits F5, IDLE creates a new
Shell with no history.
This
likely confirms the GUI process being separate than interpreter.]
The GUI process has its own interpreter, but you are correct that the
user interpreter is normally separate.
--
Terry Jan Reedy
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