I have a Windows PC and am running Python 3.4 for some time with all my code using this version. C:\Python34 and C:\Python34\Scripts are on my search path.
I want to use Google App Engine now but it seems that I will have to install Python 2.7.
I have no problems managing both versions manually for my own programs. But how about applications that run behind my back or under the covers, eg GAE, pip, etc? How would they know which or where the correct version will be?
Specifically, for GAE, can I continue to have Python 3.4 as the one with the option "Make this the Python installation the default Python installation"?
For this purpose exists a "virtualenv" tool alias virtual enviroment. More HERE.
In short, you create a container (folder/enviroment) "A" with version 2.X and another container "B" with version 3.X and inside these containers will be all scripts executed by appropriate python interpreter which you have selected during creating these containers.
Official documentation of virtualenv is aimed to UNIX/Linux systems, so for you as WIN's user might be better (easier) to use "virtualenvwrapper-win". More HERE
Change the Paths in system control panel
Or set PATH value in cmd line before running 3PP programs
Related
I am currently starting a business where I will be providing support to clients directly on their business offices. I need to be able to go to different computers and be able to run custom python scripts, my question is if there's a way to make my python environment portable?
Assuming that your users are running Windows, I see two options here.
If you have already defined which scripts you will be running, compile them into exe files using py2exe, that way you can just plug a USB and run them as needed. (the caveat is that some antivirus will automatically block the unsigned executables)
The other option is to use WinPython, that is a full python environment with a lot of packages already preinstalled that ives in it's own directory. In case you need to install a new package, just use the Powershell or CMD that comes with it and use the preinstalled "pip".
I found something interesting here Portable Python. I use that method to create portable Python 3.9 and 3.10 and everything works so have a look.
just a quick question. I have Python 2.7 on my mac by default. I have also installed 3.4 and use it more than 2.7, but would like to upgrade to the new 3.5. Should I remove 3.4 and just lay down a new install of 3.5, or is there a way to just update it. All my searches just talk about upgrading from 2.7 to 3x. I am just concerned about messing one of the installs up. Any input would be greatly appreciated.
Cheers.
It is a lot safer to change your environment so that Python 3.5 is given preference over the default Python.
There are many ways to do this; if you do them all, it provides the maximum compatibility.
You can set these in your .bash_profile file, which is a hidden file in your home directory.
You can set the PATH environment variable so that Python 3.5 appears first in the search order; like this PATH='/path/to/your/python3.5/directory':$PATH
You can set a local alias in your shell, so that the python command points to Python 3.5, like this alias python="/path/to/the/file/python3.5"
Once you set the above, make sure you restart the terminal application.
If you download the installer form python.org; it will set these environment variables for you.
Also, if you use a utility like brew it will set the shell up correctly for you.
This will ensure that the shell environment will point to version of Python you want; however this does not affect applications that run on the desktop as most of them don't read the shell environment variables.
So, if you are using and IDE like PyCharm you'll still have to manually set the correct Python version for your projects.
This may seem like a lot of workaround, but on most Linux systems and even on OSX, Python is a core part of the system and it is used by some utilities, therefore it is always dangerous to rip and replace the version of Python that came with the operating system.
I'm a newbie programmer just installing Python 3.2, but I know I also have an older version of Python on my machine. in fact, I think Macbook comes with it installed. Do I have to worry about having different versions on my computer when I try to start learning Python?
For the most part, you don't have to worry about conflicts with system Python. In fact it is recommended to install a different Python version instead of working with system Python. Also consider using virtualenv and virtualenvwrapper to maintain any dependencies for each project easily without conflicts.
It really depends what OS you're talking about. I'm assuming you're talking about a Mac, since you mentioned Macbook.
Macs come with 2.5 and 2.6 installed as far as I'm aware. At least mine has both those versions, and I've only installed 2.7 manually.
You can check which version of python is the current 'system' python by doing the following in terminal:
// check the version of system python
python --version
// tells you where the system version of python is on your PATH
which python
On *nix type Operating Systems, like your Mac, applications aren't really 'installed', like they are in Windows (eliding details). Instead, application files are placed in various different parts of the file system. Python, for example, is placed into the following directory (by default) when installing 2.7:
/Library/Frameworks/Python.framework/Versions/2.7/bin/python
Since this directory isn't on the system PATH, this version of python won't be used when simply calling python from the command line. The system will search all the folders in the PATH environment variable for an executable file called python. It will usually find it in /usr/bin/ or something similar.
To make a new version of Python the 'system' python, you have a couple of options:
Modify your .bash_profile, and prepend the path to your new python to the PATH environment variable.
symlink the new version of python to a directory already on your PATH like /usr/bin/
Be aware that Mac python installers can modify your .bash_profile (in your home directory), to force the new version to be the default system version. This is what my bash_profile shows:
# Setting PATH for Python 2.7
# The orginal version is saved in .bash_profile.pysave
PATH="/Library/Frameworks/Python.framework/Versions/2.7/bin:${PATH}"
export PATH
You can happily run multiple versions of python on the same system. A particular version is usually the default though, and that's whatever executable python file is found on the PATH first.
If you want to use a different version at any particular point in time, you can:
/path/to/python/2.4/python some_script.py
/path/to/python/2.7/python some_script.py
/path/to/python/3.2/python some_script.py
That will execute the script some_script.py under 3 different versions of python. Of course, you need to make sure that the /path/to/python is correct.
So yes, you need to be mindful about what version of python you are going to be using, hopefully this will guide you into understanding how applications are installed and which version of an application is launched by default when you don't provide a path.
Yes, 3.x Python syntax is not backward-compatible with 2.x. So if you learn Python 3.x you might not be able to port your knowledge to Python 2.x.
Moreover you should choose if you want to learn 3.x or 2.x. 2.x is far more widespread than 3.x, but 3.x is where Python is heading. No more innovation will happen in 2.x, and in mid-term most frameworks will be ported to 3.x (right now there are some notable exceptions)
Hope that helps!
In general, you should be fine. Since the Mac is BSD-based, it should maintain the "python" command as pointing to the version that your system requires, which is usually an older version like 2.5. You may have to use a command like python3 to run your Python 3 programs, but other than that it should be transparent to you.
As you learn and become more advanced, you can begin using the virtualenv system to maintain separate Python installations for multiple projects.
Python version with different major or minor version numbers can be installed in parallel. For example, you can have 2.4, 2.5, 2.6, 2.7 and 3.1 on the same machine. However, you can't have versions with the same major and minor number installed at the same time (at least, not without tricks), so you can't have 2.5.2 and 2.5.4 at the same time.
Note that you will have to install any third-party libraries once for every Python version.
It is very well possible to have multiple versions of python on your machine. Just make sure, that if you call python in your console it uses the python you want it to use. Same goes for your IDE.
Regarding the version: It is always nice to have the latest version on board (in python however there are compatibility issues to take into account) , since there might be features you want to use, that are only available with a certain version and upwards. Since this is sometimes tricky to find out, especially if you are new to the field, going with the latest version might be how you should proceed.
Be careful before installing new version of python.
Python has no backward compatibility.
Scripts written for python 2.7.* won't work on python 3
For example,
print "Hello" will work on python 2.7 but not on version3
I'm looking for a way to let multiple Python programs coexist on the same Windows machine.
Here's the problem: suppose program A needs Python 2.5, B needs 2.6, C needs 3, and each of them needs its own version of Qt, Wx or whatever other modules or whatever.
Trying to install all these dependencies on the same machine will break things, e.g. you can install different versions of Python side-by-side but only one of them can have the .py file association, so if you give that to Python 2.5 then B and C won't work, etc.
The ideal state of affairs would be if program A could live in C:\A along with its own Python interpreter, Qt/Wx/MySQL driver/whatever and never touch anything outside that directory, ditto for B and C.
Is there any way to accomplish this, other than going the full virtual box route?
edit: I tried the batch file solution, but it doesn't work. That is, it works on simple test scripts but e.g. OpenRPG fails at some point in its loading process if its required version of Python doesn't own the file association.
VirtualEnv.
virtualenv is a tool to create
isolated Python environments.
The basic problem being addressed is
one of dependencies and versions, and
indirectly permissions. Imagine you
have an application that needs version
1 of LibFoo, but another application
requires version 2. How can you use
both these applications? If you
install everything into
/usr/lib/python2.4/site-packages (or
whatever your platform's standard
location is), it's easy to end up in a
situation where you unintentionally
upgrade an application that shouldn't
be upgraded.
See previous answer here.
The other tool you should look at is pip which is great for installing particular versions of a library into a virtual environment. If you need to run v 1.0 of a library in python v 2.x for one application and 1.1 of the same library in python v 2.x, for example, you will need virtualenv plus a means of installing a particular version in that environment. Virtualenv + pip is your best choice.
Use batch files to run scripts, write in notepad for example:
c:\python26\python.exe C:\Script_B\B.py
and save it as runB.bat (or anything .bat). It will run with interpreter in c:\python26\python.exe file specified after a whitespace.
One solution would be to craft a batch file that invokes the correct interpreter for a given application. THis way, you can install additional interpreters in separate folders.
Probably not perfect but it works.
Have you considered compiling them to EXEs? Once you do that, all you have to do is call the EXE, for which the machine does not require python to be installed. All the required modules etc are packaged with the distribution when you compile.
write a python script that mimics the way unix shells handle scirpts -- look at the first line and see if it matches #!(name-of-shell). Then have your python script exec that interpreter and feed it the rest of its arguments.
Then, associate .py with your script.
It looks like the best solution is a batch file that sets the file association before running the appropriate version of Python, as mentioned in the comments to one of the answers here: how to run both python 2.6 and 3.0 on the same windows XP box?
I setup PyDev with this path for the python interpreter
/System/Library/Frameworks/Python.framework/Versions/2.5/Python
since the one under /usr/bin were alias and Eclipse won't select it. I can run my python script now but cannot run the shell as an external tool. The message I get is
variable references empty selection ${resource_loc}
Same if I use {container_loc}
Any thoughts ?
Sunit
I installed the Python.org version as well, this is a must.
I finally got PyDev working in Eclipse by pointing the interpreter to:
/Library/Frameworks/Python.framework/Versions/2.6/bin/python
manually. If you don't do it manually (by using the Autoconfig) it seems to not find the right version.
Common practice seems to be to install an up-to-date Python 2.5 from python.org and use that instead of the system installation. I saw that recommended here and there when I got started on Mac OS X.
It installs under /Library (as opposed to /System/Library) so the system Python is intact. Pydev has /Library/Frameworks/Python.framework/Versions/2.5/Resources/Python.app/Contents/MacOS/Python as its configured Python interpreter and all is well.
Can't state for sure that your trouble is due only to using the system's Python installation; in any case this way I have no trouble. Also, this way when you fiddle with your development environment (install things in site-packages, upgrade Python), anything that uses the system Python is sure to be unaffected.
I know this is a ancient post... but, in case of some newbee like me to get the better answer.
I just using "Eclipse Marketplace" from the "Help" menu and search for keyword "python" or "PyDev" to get PyDev, and get it successfully installed.
AND, you should add PyDev to the top-right dock.
For the instance, my eclipse on my laptop's OSX is (Version: Indigo Service Release 2 Build id: 20120216-1857).
Have fun, folks! :)
I believe ${resource_loc} or ${container_loc} (without any argument) are based on the current selection in your workbench when you are launching your script.
So are you selecting the right resource when selecting that script through the "external tool" runner ?
At least, click on the project name before you run one of the external programs.
Note: it works with a selection in the Navigator or Package Explorers views (the latest might not be available in PyDev environment though)