python -c commands on windows.

[Terry Reedy]

On 10/21/2013 5:14 PM, random832 at fastmail.us wrote:
> On Mon, Oct 21, 2013, at 16:47, Terry Reedy wrote:
>> Manual says "-c <command>
>>       Execute the Python code in command. command can be one or more
>> statements separated by newlines, with significant leading whitespace as
>> in normal module code."
>>
>> In Windows Command Prompt I get:
>> C:\Programs\Python33>python -c "a=1\nprint(a)"
>>     File "<string>", line 1
>>       a=1\nprint(a)
>>                   ^
>> SyntaxError: unexpected character after line continuation character
>> (Same if I remove quotes.)
>>
>> How do I get this to work?
>
> Well, ignoring the "why would you want to" factor...

Because it is claimed to be possible ;-)

That particular example could be written in one line with ';'. But it is 
a minimal example that either shows the problem or obviously works. (IE, 
what we recommend people post ;-). I initially tried to test a version 
of Chris Angelico's code from another thread without writing it to a file:

def a():
   def b():
     nonlocal c

I also wanted to know if 'newline' in the doc meant a literal newline 
(it appears so, but it seemed impossible on Windows) rather than '\n' 
and if the problem was peculiar to Windows. And I need to know that to 
run "python -c ... " in a subproccess from Python.


> this actually _is_ possible.

Even on Windows .. I presume this is easier on *nix.

> C:\>python -c a=1^
> More?
> More? print(a)
> 1
>
> You can put quotes around any part of the command you need spaces in,
> but you _cannot_ have the ^ in quotes. So, with quotes, it would be as
> follows:
>
> C:\>python -c "a='1 2'"^
> More?
> More? print(a)
> 1 2

Spaces would be typical for a compound statememt header line. For a 
third line, the second should have ^ added.

> This is a very obscure feature of the command processor,

Really obscure ;-)

 > and I don't know if it works inside a batch file.

It does:
---tem.bat
python -c "def f(a):"^

"  print(a+1)"^

f(2)
---Command Prompt
C:\Programs\Python33>\Users\Terry\Documents\tem

C:\Programs\Python33>python -c "def f(a):"
"  print(a+1)"
f(2)
3
---
3 lines echoed (they could have been suppressed) plus output.

-- 
Terry Jan Reedy