Vedr: What does """ means in python?

[Duncan Booth]

Gisle Vanem <gvanem at yahoo.no> wrote:

> Regrading handy uses of ''', you learned me one trick when using Pythonÿ
> code in a Windows .bat file:
> 
>  rem = '''
>  @echo off
>  echo This is batch
>  \python32\python %0
>  echo All done
>  exit /b
>  rem '''
>  import sys
>  print("This is Python")
>  for i,p in enumerate(sys.path):
>     print('sys.path[%2d]: %s' % (i, p))
>  print("Python done")
> You'll have a variable in Python called 'rem' which contains all 
> your
> batch code :) It exploits the fact that 'rem' makes a 
> one-line
> comment, but the triple quotes go across multiple lines.
> 
A better trick would be to use a Powershell script instead of a batch 
file:

-------------------------------------------
filter python() { $_ | c:\Python33\python.exe ($args -replace'(\\*)"','$1$1\"') }

Write-Host "This is the powershell script"

dir cert: | convertto-json | python -c @"
import json, sys
stores = json.loads(sys.stdin.read())
print("This is Python")
for store in stores:
    print("{}: {}".format(store['PSChildName'], ', '.join(store['StoreNames'])))
print("Python done")
"@

Write-Host "All done"
-------------------------------------------
C:\scripts> . .\Pythoncerts.ps1
This is the powershell script
This is Python
CurrentUser: Root, UserDS, Disallowed, Trust, My, TrustedPublisher, SmartCardRoot, TrustedPeople, ADDRESSBOOK, AuthRoot,
 McAfee Trust, CA, REQUEST, ACRS
LocalMachine: Disallowed, Trust, CA, TrustedPublisher, SmartCardRoot, My, TrustedPeople, AuthRoot, TrustedDevices, Root
Python done
All done
C:\scripts>

Notes on the above:

Powershell messes up arguments when running legacy programs. The filter 
ensures that all arguments pass through Windows command line processing 
unscathed (except they can't contain null characters). You don't actually 
have to use the filter if you are careful about how you write quotes in the 
code, but it makes life simpler.

Python scripts up to just over 32,000 characters can be written on the 
command line this way. You can also assign the script to a variable and 
keep the Python command a bit cleaner:

   $script = @"
   print("Python here!")
   "@
   python -c $script

Or without the filter it is best to avoid the double quotes:

   $script = @"
   print('Python here!')
   "@
   c:\python33\python.exe -c $script

To run from a traditional cmd.exe prompt you have to explicitly use 
Powershell. The default file associations for .ps1 files will run notepad 
instead.

If your system execution policy is Restricted (the default) use:

    powershell -executionpolicy RemoteSigned .\Pythoncerts.ps1

Otherwise set the execution policy to something more lenient (at a 
Powershell prompt running as administrator enter "Set-ExecutionPolicy 
RemoteSigned") and you can just do:

    powershell .\Pythoncerts.ps1

I also use Powershell interactively so I have the filters defined in my 
startup ($Home\Documents\WindowsPowerShell\profile.ps1):

  filter py() { $_ | py.exe ($args -replace'(\\*)"','$1$1\"') }
  filter python() { $_ | c:\Python33\python.exe ($args -replace'(\\*)"','$1$1\"') }

-- 
Duncan Booth