Re: Why does IDLE use a subprocess?
On Tuesday, May 30th, 2023 at 10:18 PM, Chris Angelico wrote:
> Yep, what you're seeing there is the namespace and nothing else. But
> if you mess with an actual builtin object, it'll be changed for the
> other interpreter too.
>
> > > > import ctypes
> > > > ctypes.cast(id(42), ctypes.POINTER(ctypes.c_int))[6] = 43
> > > > 41+1
>
> 43
>
> > > > from code import InteractiveInterpreter
> > > > interp = InteractiveInterpreter()
> > > > interp.runcode("print(41+1)")
>
> 43
>
> (Note that this only works in CPython and only with integers small
> enough to be in the cache, meaning that there is only one such object
> representing that integer.)
>
> The same is true of C extensions, which often have their own internal
> state, and that state isn't isolated to a single interpreter.
>
> Better isolation is coming with PEP 554
> https://peps.python.org/pep-0554/ which also has some great
> information about what currently is NOT isolated. (Also, even then,
> some things won't be fully isolated; I think that the ctypes trick
> above might still affect a subinterpreter even in a post-PEP554
> world.)
Amazing example! Thank you everyone for the detailed responses - will be sure
to check out the PEP as well.
Jim
--
https://mail.python.org/mailman/listinfo/python-list
Re: Best practice for database connection
On 01/06/2023 06.45, Thomas Passin wrote:
On 5/31/2023 2:10 PM, Jason Friedman wrote:
I'm trying to reconcile two best practices which seem to conflict.
1) Use a _with_ clause when connecting to a database so the connection is
closed in case of premature exit.
class_name = 'oracle.jdbc.OracleDriver'
url = f"jdbc:oracle:thin:@//{host_name}:{port_number}/{database_name}"
with jdbc.connect(class_name, url, [user_name, password],
jdbc_jar_file.as_posix()) as connection:
logger.info(f"Connected.")
2) Use self-made functions to streamline code. For example, there are
several places I need to know if the database object is a particular
type,
so I create a function like this:
foobar_set = set()
...
def is_foobar(connection: jdbc.Connection, name: str) -> bool:
"""
:param connection: connection object
:param name: owner.object
:return: True if this object is of type foobar
"""
global foobar_set
if not foobar_set:
query = f"""select stuff from stuff"""
cursor = connection.cursor()
cursor.execute(query)
for owner, object_name in cursor.fetchall():
foobar_set.add(f"{owner}.{object_name}")
cursor.close()
return name.upper() in foobar_set
But that requires that I call is_foobar() with a connection object.
Essentially I'd like a function that leverages the one connection I
create
at the beginning using a with clause.
If you need to have a connection object that persists outside of the
with block, then
1. you can just not use a "with" block:
connection = jdbc.connect(class_name, url, [user_name, password],
jdbc_jar_file.as_posix())
You will want to close the connection yourself when you are done with it.
2. do all the subsequent work within the "with" block.
As with many such questions, the answer is "it depends". Sadly that's no
help!
Please consider: is the database critical to this application? In other
words, if the script is unable to proceed without access, eg RDBMS is
down or credentials are not accepted, then must the logic simply stop?
Most of mine fit into that category. Accordingly, script-execution
starts with setting the environment, eg gathering credentials; followed
by establishing a connection to the RDBMS. An operational RDBMS is part
of the environment! Now (wait for many of our colleagues to hurriedly
suck in their breath) we can see that the connection is a global-value -
something which resides in a base "frame" of the Python stack, and is
accordingly available (R-O) 'everywhere'.
NB when I say "connection", it is part of a wider RDBMS-interface object.
If you wish to use a Context Manager, then its only content may be a
call to main() - or preferably a function which better describes what
the application will do. (per @Thomas' contribution)
PS I don't like using the global keyword/command, but prefer to pass the
connection as a parameter. A matter of style? A "contract":
no-connection, no-query? YMMV...
Another approach might be to enact the Dependency Inversion Principle
(one of 'Uncle Bob' Martin's SOLID Principles. In this case, proceed
with the application, and when it comes time to issue a query against
the database, ask the question: "does a connection exist?". In the
negative case, then call a routine which establishes the connector,
passes that to the query-routine, and proceeds.
Assuming multiple query-routines, the problem with this is that it takes
some sleight-of-hand to create a shared connection. Alternately, maybe
the application is prepared to assume the 'cost' of creating multiple
connections (over time) because the RDBMS-interactions are few-and-far
between, or only a small part of the total.
I don't use one, but others enthuse about ORMs, eg SQLAlchemy. This
suits those who combine RDBMS and OOP, and has its own persistence
methodology.
--
Regards,
=dn
--
https://mail.python.org/mailman/listinfo/python-list
Re: Log File
On 2023-05-31 00:22:11 -0700, ahsan iqbal wrote: > Why we need a log file ? A log file contains information about what your program was doing. You use it to check that your program was performing as intended after the fact. This is especially useful for tracking down problems with programs which are either long-running or are running unattended. For example, if a user tells me that they were having a problem yesterday evening I can read the log file to see what my program was doing at the time which will help me to pin down the problem. The important part to remember is that a log file will only contain information the program writes. If you didn't think to log some information then it won't be in the log file and you can't look it up afterwards. On the other hand you don't want to log too much information because that might cause performance problems, it might fill up your disks and it will be a chore to find the relevant information in a sea of irrelevant details. So deciding what to log is a bit of an art. > If i read a large text file than how log file help me in this regard? It won't help you with reading the file. However, you might want to log some information about operation, e.g. when you started (log files usually contain time stamps), when you ended, how large the file was, etc. That way you can compare different runs (has the file increased in size over the last month? Was reading especially slow yesterday?). You could also log a status message every once in a while (e.g. every 100 MB or every 10 lines). That will give you reassurance that the program is working and a rough estimate when it will be finished. Or you can log any other information you think might be useful. hp -- _ | Peter J. Holzer| Story must make more sense than reality. |_|_) || | | | h...@hjp.at |-- Charles Stross, "Creative writing __/ | http://www.hjp.at/ | challenge!" signature.asc Description: PGP signature -- https://mail.python.org/mailman/listinfo/python-list
Re: Fwd: Problems Installing and getting started.
On 5/31/2023 3:52 PM, Dennis Lee Bieber wrote: Python does not provide, normally, a "click me" icon to run Python. Python is a command line language INTERPRETER/COMPILER. If file associations are set up, clicking on a script (.py) file/will/ run it -- but the window it opens goes away as soon as the script completes. Instead one opens a command shell window and runs Python/scripts from that window... Microsoft Windows [Version 10.0.19045.2965] (c) Microsoft Corporation. All rights reserved. C:\Users\Owner>python Python 3.10.11 (tags/v3.10.11:7d4cc5a, Apr 5 2023, 00:38:17) [MSC v.1929 64 bit (AMD64)] on win32 Type "help", "copyright", "credits" or "license" for more information. On Windows, typing "python" may or may not give the expected version depending in what has been installed before. With the python.org installation, it's better to type "py" instead (this is Windows only). For example, on my Windows 10 computer" python Python 3.9.9 (tags/v3.9.9:ccb0e6a, Nov 15 2021, 18:08:50) [MSC v.1929 64 bit (AMD64)] on win32 Type "help", "copyright", "credits" or "license" for more information. >>> but - py Python 3.11.3 (tags/v3.11.3:f3909b8, Apr 4 2023, 23:49:59) [MSC v.1934 64 bit (AMD64)] on win32 Type "help", "copyright", "credits" or "license" for more information. >>> -- https://mail.python.org/mailman/listinfo/python-list
Re: Fwd: Problems Installing and getting started.
On Wed, 31 May 2023 08:34:48 +0100, Mark Bass declaimed the following: >-- Forwarded message - >From: Mark Bass >Date: Wed, 31 May 2023 at 08:09 >Subject: Problems Installing and getting started. >To: > > >Good morning, > >I installed python several hours ago (from python.org), I then installed >the IDE PyCharm. I'm using AI to help with a project that requires >statistical analysis. >I cannot open python, when I double clicked a "Modify Setup" window >appeared with the three options Modify, Repair and Uninstall to click. I >assumed this was part of the final installation process and clicked Modify >- it seemed to be successful. I still could not open python. I asked the AI >and it suggested to click Repair, this still made no difference. I finally >Uninstalled it, shut down my laptop, had a coffee then re-installed it but >the same problem occurred. >Can you help ? Any suggestions? >I'm really pleased with the AI so far and looking forward to using Python >to get my project started. >Best Regards.Mark You are RERUNNING the Python installer package. Once you installed Python -- move that installer package to some safe/obscure location on your computer (you should only need it if you really need to fix an error with the installation). Python does not provide, normally, a "click me" icon to run Python. Python is a command line language INTERPRETER/COMPILER. If file associations are set up, clicking on a script (.py) file /will/ run it -- but the window it opens goes away as soon as the script completes. Instead one opens a command shell window and runs Python/scripts from that window... Microsoft Windows [Version 10.0.19045.2965] (c) Microsoft Corporation. All rights reserved. C:\Users\Owner>python Python 3.10.11 (tags/v3.10.11:7d4cc5a, Apr 5 2023, 00:38:17) [MSC v.1929 64 bit (AMD64)] on win32 Type "help", "copyright", "credits" or "license" for more information. >>> C:\Users\Owner>dir *.py Volume in drive C is Sys_OS Volume Serial Number is B650-6F92 Directory of C:\Users\Owner 04/15/2023 04:57 PM50 junk.py 1 File(s) 50 bytes 0 Dir(s) 1,884,894,617,600 bytes free C:\Users\Owner>python junk.py 2 4 6 8 10 12 C:\Users\Owner>junk.py 2 4 6 8 10 12 C:\Users\Owner> Note: depending upon your environment, neither file associates nor Python may be set up on the path. You may have a "py" command that is set up to find and run Python (and allow specifying which version if you have multiple versions (in different directories). Also, you may be affected by whether Python was installed for "all users" or just the account that did the install. -- https://mail.python.org/mailman/listinfo/python-list
Re: Best practice for database connection
On 5/31/2023 2:10 PM, Jason Friedman wrote:
I'm trying to reconcile two best practices which seem to conflict.
1) Use a _with_ clause when connecting to a database so the connection is
closed in case of premature exit.
class_name = 'oracle.jdbc.OracleDriver'
url = f"jdbc:oracle:thin:@//{host_name}:{port_number}/{database_name}"
with jdbc.connect(class_name, url, [user_name, password],
jdbc_jar_file.as_posix()) as connection:
logger.info(f"Connected.")
2) Use self-made functions to streamline code. For example, there are
several places I need to know if the database object is a particular type,
so I create a function like this:
foobar_set = set()
...
def is_foobar(connection: jdbc.Connection, name: str) -> bool:
"""
:param connection: connection object
:param name: owner.object
:return: True if this object is of type foobar
"""
global foobar_set
if not foobar_set:
query = f"""select stuff from stuff"""
cursor = connection.cursor()
cursor.execute(query)
for owner, object_name in cursor.fetchall():
foobar_set.add(f"{owner}.{object_name}")
cursor.close()
return name.upper() in foobar_set
But that requires that I call is_foobar() with a connection object.
Essentially I'd like a function that leverages the one connection I create
at the beginning using a with clause.
If you need to have a connection object that persists outside of the
with block, then
1. you can just not use a "with" block:
connection = jdbc.connect(class_name, url, [user_name, password],
jdbc_jar_file.as_posix())
You will want to close the connection yourself when you are done with it.
2. do all the subsequent work within the "with" block.
--
https://mail.python.org/mailman/listinfo/python-list
Best practice for database connection
I'm trying to reconcile two best practices which seem to conflict.
1) Use a _with_ clause when connecting to a database so the connection is
closed in case of premature exit.
class_name = 'oracle.jdbc.OracleDriver'
url = f"jdbc:oracle:thin:@//{host_name}:{port_number}/{database_name}"
with jdbc.connect(class_name, url, [user_name, password],
jdbc_jar_file.as_posix()) as connection:
logger.info(f"Connected.")
2) Use self-made functions to streamline code. For example, there are
several places I need to know if the database object is a particular type,
so I create a function like this:
foobar_set = set()
...
def is_foobar(connection: jdbc.Connection, name: str) -> bool:
"""
:param connection: connection object
:param name: owner.object
:return: True if this object is of type foobar
"""
global foobar_set
if not foobar_set:
query = f"""select stuff from stuff"""
cursor = connection.cursor()
cursor.execute(query)
for owner, object_name in cursor.fetchall():
foobar_set.add(f"{owner}.{object_name}")
cursor.close()
return name.upper() in foobar_set
But that requires that I call is_foobar() with a connection object.
Essentially I'd like a function that leverages the one connection I create
at the beginning using a with clause.
--
https://mail.python.org/mailman/listinfo/python-list
Re: Fwd: Problems Installing and getting started.
On 2023-05-31 08:34, Mark Bass wrote: -- Forwarded message - From: Mark Bass Date: Wed, 31 May 2023 at 08:09 Subject: Problems Installing and getting started. To: Good morning, I installed python several hours ago (from python.org), I then installed the IDE PyCharm. I'm using AI to help with a project that requires statistical analysis. I cannot open python, when I double clicked a "Modify Setup" window appeared with the three options Modify, Repair and Uninstall to click. I assumed this was part of the final installation process and clicked Modify - it seemed to be successful. I still could not open python. I asked the AI and it suggested to click Repair, this still made no difference. I finally Uninstalled it, shut down my laptop, had a coffee then re-installed it but the same problem occurred. Can you help ? Any suggestions? I'm really pleased with the AI so far and looking forward to using Python to get my project started. What do you mean by "open python"? You said that a "Modify Setup" window appeared, which sounds like you're clicking on the *installer*. To make it clear, the file that you download from python.org is the installer. It installs Python only. It's not an IDE. Having said that, the standard distribution from python.org does come with IDLE. You should be running PyCharm that you installed; that's the IDE. You just need to ensure that it's using the version of Python that you've installed. -- https://mail.python.org/mailman/listinfo/python-list
Re: Resolution of paths in tracebacks
On 2023-05-31, Vishal Chandratreya wrote: > When an exception occurs, the full path to the file from which it > originates is displayed, but redundant elements are not removed. For > instance: > $ ./python ./foo > Traceback (most recent call last): > File "/home/User/cpython/./foo", line 4, in > a() > File "/home/User/cpython/./foo", line 3, in a > def a(): raise ValueError > ValueError > This happens because the function _Py_abspath (in Python/fileutils.c) > appends relative_path_to_file to absolute_path_to_current_working_directory. > Not sure if this should be treated as a bug, because the definition of > 'absolute path' is not clear. Does it mean a path starting from the root > directory, or a path without redundant elements? The former: https://www.linuxfoundation.org/blog/blog/classic-sysadmin-absolute-path-vs-relative-path-in-linux-unix -- https://mail.python.org/mailman/listinfo/python-list
Re: Problems Installing and getting started.
How are you trying to “Open” python? If you get that option screen, that sounds like you are trying to run the installer again. Knowing your Operating System would be very helpful. Python is normally run from the command line, or since you have the PyCharm IDE, it can run python on the program you have loaded into the project. > On May 31, 2023, at 11:55 AM, Mark Bass wrote: > > -- Forwarded message - > From: Mark Bass > Date: Wed, 31 May 2023 at 08:09 > Subject: Problems Installing and getting started. > To: > > > Good morning, > > I installed python several hours ago (from python.org), I then installed > the IDE PyCharm. I'm using AI to help with a project that requires > statistical analysis. > I cannot open python, when I double clicked a "Modify Setup" window > appeared with the three options Modify, Repair and Uninstall to click. I > assumed this was part of the final installation process and clicked Modify > - it seemed to be successful. I still could not open python. I asked the AI > and it suggested to click Repair, this still made no difference. I finally > Uninstalled it, shut down my laptop, had a coffee then re-installed it but > the same problem occurred. > Can you help ? Any suggestions? > I'm really pleased with the AI so far and looking forward to using Python > to get my project started. > Best Regards.Mark > -- > https://mail.python.org/mailman/listinfo/python-list -- https://mail.python.org/mailman/listinfo/python-list
Fwd: Problems Installing and getting started.
-- Forwarded message - From: Mark Bass Date: Wed, 31 May 2023 at 08:09 Subject: Problems Installing and getting started. To: Good morning, I installed python several hours ago (from python.org), I then installed the IDE PyCharm. I'm using AI to help with a project that requires statistical analysis. I cannot open python, when I double clicked a "Modify Setup" window appeared with the three options Modify, Repair and Uninstall to click. I assumed this was part of the final installation process and clicked Modify - it seemed to be successful. I still could not open python. I asked the AI and it suggested to click Repair, this still made no difference. I finally Uninstalled it, shut down my laptop, had a coffee then re-installed it but the same problem occurred. Can you help ? Any suggestions? I'm really pleased with the AI so far and looking forward to using Python to get my project started. Best Regards.Mark -- https://mail.python.org/mailman/listinfo/python-list
Regarding- Issue on package install
I have an issue on updating both pip and setup tools, setuptools latest
version is getting installed successfully but after giving ok still its
shows to update.
pip is not getting installed and it shows some error.
Help me please with these issue.
pip error:
Collecting pip==23.1.2
Using cached pip-23.1.2-py3-none-any.whl (2.1 MB)
Installing collected packages: pip
Attempting uninstall: pip
Found existing installation: pip 23.0
Uninstalling pip-23.0:
Successfully uninstalled pip-23.0
Rolling back uninstall of pip
Moving to c:\users\rajesh.k\appdata\roaming\python\python38\scripts\
from C:\Users\RAJESH.K\AppData\Roaming\Python\Python38\~cripts
Moving to
c:\users\rajesh.k\appdata\roaming\python\python38\site-packages\pip-23.0.dist-info\
from
C:\Users\RAJESH.K\AppData\Roaming\Python\Python38\site-packages\~ip-23.0.dist-info
Moving to
c:\users\rajesh.k\appdata\roaming\python\python38\site-packages\pip\
from C:\Users\RAJESH.K\AppData\Roaming\Python\Python38\site-packages\~ip
ERROR: Exception:
Traceback (most recent call last):
File
"C:\Users\RAJESH.K\AppData\Roaming\Python\Python38\site-packages\pip\_internal\cli\base_command.py",
line 160, in exc_logging_wrapper
status = run_func(*args)
File
"C:\Users\RAJESH.K\AppData\Roaming\Python\Python38\site-packages\pip\_internal\cli\req_command.py",
line 247, in wrapper
return func(self, options, args)
File
"C:\Users\RAJESH.K\AppData\Roaming\Python\Python38\site-packages\pip\_internal\commands\install.py",
line 503, in run
installed = install_given_reqs(
File
"C:\Users\RAJESH.K\AppData\Roaming\Python\Python38\site-packages\pip\_internal\req\__init__.py",
line 73, in install_given_reqs
requirement.install(
File
"C:\Users\RAJESH.K\AppData\Roaming\Python\Python38\site-packages\pip\_internal\req\req_install.py",
line 796, in install
install_wheel(
File
"C:\Users\RAJESH.K\AppData\Roaming\Python\Python38\site-packages\pip\_internal\operations\install\wheel.py",
line 729, in install_wheel
_install_wheel(
File
"C:\Users\RAJESH.K\AppData\Roaming\Python\Python38\site-packages\pip\_internal\operations\install\wheel.py",
line 646, in _install_wheel
generated_console_scripts = maker.make_multiple(scripts_to_generate)
File
"C:\Users\RAJESH.K\AppData\Roaming\Python\Python38\site-packages\pip\_vendor\distlib\scripts.py",
line 436, in make_multiple
filenames.extend(self.make(specification, options))
File
"C:\Users\RAJESH.K\AppData\Roaming\Python\Python38\site-packages\pip\_internal\operations\install\wheel.py",
line 427, in make
return super().make(specification, options)
File
"C:\Users\RAJESH.K\AppData\Roaming\Python\Python38\site-packages\pip\_vendor\distlib\scripts.py",
line 425, in make
self._make_script(entry, filenames, options=options)
File
"C:\Users\RAJESH.K\AppData\Roaming\Python\Python38\site-packages\pip\_vendor\distlib\scripts.py",
line 325, in _make_script
self._write_script(scriptnames, shebang, script, filenames, ext)
File
"C:\Users\RAJESH.K\AppData\Roaming\Python\Python38\site-packages\pip\_vendor\distlib\scripts.py",
line 249, in _write_script
launcher = self._get_launcher('t')
File
"C:\Users\RAJESH.K\AppData\Roaming\Python\Python38\site-packages\pip\_vendor\distlib\scripts.py",
line 404, in _get_launcher
raise ValueError(msg)
ValueError: Unable to find resource t32.exe in package pip._vendor.distlib
[notice] A new release of pip is available: 23.0 -> 23.1.2
[notice] To update, run: python.exe -m pip install --upgrade pip
i tried this too but it didn't work.
--
https://mail.python.org/mailman/listinfo/python-list
Resolution of paths in tracebacks
When an exception occurs, the full path to the file from which it
originates is displayed, but redundant elements are not removed. For
instance:
$ ./python ./foo
Traceback (most recent call last):
File "/home/User/cpython/./foo", line 4, in
a()
File "/home/User/cpython/./foo", line 3, in a
def a(): raise ValueError
ValueError
This happens because the function _Py_abspath (in Python/fileutils.c)
appends relative_path_to_file to absolute_path_to_current_working_directory.
Not sure if this should be treated as a bug, because the definition of
'absolute path' is not clear. Does it mean a path starting from the root
directory, or a path without redundant elements? The os module, for
instance, does the following.
$ ./python
>>> import os.path
>>> os.path.isabs('/home/..')
True
>>> os.path.abspath('/home/..')
'/'
Either way: should the traceback display the path without redundant
elements?
I am using CPython 3.13.0a0 (595ffddb33e95d8fa11999ddb873d08e3565d2eb).
--
https://mail.python.org/mailman/listinfo/python-list
Re: Log File
On 5/31/23 00:22, ahsan iqbal wrote: Why we need a log file ? If i read a large text file than how log file help me in this regard? If you were parsing each line of this text file looking for information, perhaps some of the lines would not be formatted correctly, and you would be unable to get the information from those lines. Maybe you would like to write those bad lines to a log file so that you could analyze them later. -- https://mail.python.org/mailman/listinfo/python-list
Log File
Why we need a log file ? If i read a large text file than how log file help me in this regard? -- https://mail.python.org/mailman/listinfo/python-list
