PR: Fix restart mechanism for the Windows standalone installer (Installers)

[dalthviz]

Description of Changes

Be sure to use the script the standalone installer uses in the shortcut to start and don't remove installer pkgs entry from the PYTHONPATH when starting Spyder.

Issue(s) Resolved

See #20658 (comment)

Affirmation

By submitting this Pull Request or typing my (user)name below,
I affirm the Developer Certificate of Origin
with respect to all commits and content included in this PR,
and understand I am releasing the same under Spyder's MIT (Expat) license.

I certify the above statement is true and correct: dalthviz

[ccordoba12]

Left a small suggestion for you @dalthviz, otherwise looks good to me.

[ccordoba12]

@mrclary, it seems one of the patches for the Linux installer is not applying cleanly now. What can we do about that?

[mrclary]

It is probably because there is a merge conflict with the patch. This should be resolved by rebasing the patch branch and resolving any conflicts. I'll take a look to be sure and fix any issues I find.

[mrclary]

Regarding this PR, why does the Windows Spyder application require adding package paths to the user's PYTHONPATH? That seems unreliable as PYTHONPATH is intended for user customization and may be modified for any reason. Will the conda-based installer for Windows require use of PYTHONPATH as well?

[mrclary]

Okay, there is a direct merge conflict between the patch and the changes in this PR.
My recommendation is to move forward with this PR and ignore the failing conda-based installer failure. After this PR is merged, I'll rebase the patch branch and resolve the conflict, verifying that the conda-based Linux installer successfully builds.

[dalthviz]

why does the Windows Spyder application require adding package paths to the user's PYTHONPATH?

I think that's the way pynsist works. Checking the .pyw script that pynsist creates to launch an application you can see the addition of the packages dir to PYTHONPATH. I think pynsist also does some setup with .pth files which, from what I understand, require the addition of the pkgs path to the PYTHONPATH. Just in case, the Spyder-launch.pyw script is this:

#!python3.8
import sys, os
import site
scriptdir, script = os.path.split(os.path.abspath(__file__))
installdir = scriptdir  # for compatibility with commands
pkgdir = os.path.join(scriptdir, 'pkgs')
sys.path.insert(0, pkgdir)
# Ensure .pth files in pkgdir are handled properly
site.addsitedir(pkgdir)
os.environ['PYTHONPATH'] = pkgdir + os.pathsep + os.environ.get('PYTHONPATH', '')

# APPDATA should always be set, but in case it isn't, try user home
# If none of APPDATA, HOME, USERPROFILE or HOMEPATH are set, this will fail.
appdata = os.environ.get('APPDATA', None) or os.path.expanduser('~')

if 'pythonw' in sys.executable:
    # Running with no console - send all stdstream output to a file.
    kw = {'errors': 'replace'} if (sys.version_info[0] >= 3) else {}
    sys.stdout = sys.stderr = open(os.path.join(appdata, script+'.log'), 'w', **kw)
else:
    # In a console. But if the console was started just for this program, it
    # will close as soon as we exit, so write the traceback to a file as well.
    def excepthook(etype, value, tb):
        "Write unhandled exceptions to a file and to stderr."
        import traceback
        traceback.print_exception(etype, value, tb)
        with open(os.path.join(appdata, script+'.log'), 'w') as f:
            traceback.print_exception(etype, value, tb, file=f)
    sys.excepthook = excepthook



if __name__ == '__main__':
    from spyder.app.start import main
    main()

Will the conda-based installer for Windows require use of PYTHONPATH as well?

I don't think so since with the conda-based installer the installation is basically a conda env, right?

[mrclary]

So pynsist creates the Spyder-launch.pyw script you listed?
It makes sense to me that pkgdir should be added to sys.path

sys.path.insert(0, pkgdir)
# Ensure .pth files in pkgdir are handled properly
site.addsitedir(pkgdir)

But I don't know why it is added to os.environ['PYTHONPATH']

os.environ['PYTHONPATH'] = pkgdir + os.pathsep + os.environ.get('PYTHONPATH', '')

Yes, the conda-based installers are exactly a conda installation, just in a non-standard location. You asked elsewhere whether we could use an nsist template for the conda-based installer, and I believe that we can. I don't know exactly what the template will do compared to the our existing Windows installer, e.g. will it generate the same Spyder-launch.pyw? I suppose we'll just have to cross that bridge when we get to it.

[dalthviz]

@ccordoba12 @mrclary should we merge this one as it is, right?

[mrclary]

@ccordoba12 @mrclary should we merge this one as it is, right?

I think so. I'll resolve conflicts with the conda-based installer patch branch after this PR is merged.
I did not intend to hijack or delay this PR with my most recent questions/comments regarding PYTHONPATH.

[dalthviz]

I think so. I'll resolve conflicts with the conda-based installer patch branch after this PR is merged.

👍

I did not intend to hijack or delay this PR with my most recent questions/comments regarding PYTHONPATH.

Not at all! And in fact, quite interesting questions to think about in order to understand better what we need to do to migrate from the old installers 👍

[ccordoba12]

Thanks @dalthviz!