[Tutor] Interpreter pasting Question

[Avi Gross]

Steven,

Thanks. You are right. I am no longer going to talk IDLE worship!

When I open up a command window and run what I assumed was the same version
of python, no problems. Should have tried that but frankly that means I am
stuck with having to then do other things differently like reloading an
edited file. Oh well.

It sounds like the problem is that IDLE is (invisibly) intercepting what I
type or paste and then passing it on to a slaved interpreter. There likely
are other side effects and another editor/environment may not have this
issue. I will try some.

As one of my programming styles includes lots of hands-on incremental
analysis of bits and pieces to get them working before combining them,  I
have no time for an idyllic experience.

OK, just kidding. Nice to have choices and I particularly want to move on to
using notebooks in which I can have batches of code I can run inline and
even interleave bits of multiple languages. 

Yes, I am aware that my experiments with exec are not testing the same
thing. They do indicate ways to get around the issue even using IDLE and I
am now thinking of ways to do more dynamic things by building code and then
executing it. So, not really time wasted. The fact that python relies on
indentation means you can have problems if things are not aligned just
right.

Here is my work-around if I happen to be using IDLE and want to copy in
something huge from say a web page.

Type this:

Cmd = """

Do the paste.

Type on a line by itself:

"""

Now type

exec(Cmd)

May not work all the time, but perhaps a reasonable work around.

-----Original Message-----
From: Tutor <tutor-bounces+avigross=verizon.net at python.org> On Behalf Of
Steven D'Aprano
Sent: Friday, December 28, 2018 1:58 AM
To: tutor at python.org
Subject: Re: [Tutor] Interpreter pasting Question

On Fri, Dec 28, 2018 at 12:58:00AM -0500, Avi Gross wrote:

[...]
> Copying and pasting multiple lines into the interpreter fails in 
> mysterious ways, unless they are a logical single entity.
> 
> Is there a way to change this behavior, or perhaps an 
> editor/environment that feeds multiple lines more carefully to the
interpreter?

Which interpreter are you using?

If it is the regular Python REPL (Read Eval Print Loop), then pasting
multiple lines should work, with some limitations. For example, I can
paste:

x = 5
y = 6

as two lines, and it works fine under Linux. I see no reason why it should
be different under Windows.

If you just run "python" in the Windows shell (cmd.exe or whatever its
called), you should get an interactive interpreter. What happens when you
paste multiple lines in that?



[...]
> When copied in looks like this:
> 
> >>> X=5
> 
> Y=6
> 
> SyntaxError: multiple statements found while compiling a single 
> statement

That looks like a bug. Are you using IDLE? Perhaps it has been fixed in
newer versions of Python, and if not, you should report it as a bug on the
bugtracker

https://bugs.python.org/

but:

(1) try searching for similar bug reports first;
(2) read this first: 

    http://www.sscce.org/

(3) and do try to keep your bug report short and to the point.


It looks like others have this problem with IDLE too:

https://duckduckgo.com/?q=idle+paste+multiple+lines


IPython/Jupyter allows pasting of multiple lines; I expect that bpython will
too.

https://ipython.org/

https://bpython-interpreter.org/


But as I said, the vanilla Python REPL ought to work. How are you starting
the interpreter? My guess is that you're using IDLE.



[...]
> Python has an eval() and an exec() and I would assume the latter would be
a
> way to see what works.

No, exec() executes Python code, it doesn't try to simulate a REPL.


> Here are three lines using \n:
> 
> >>> exec("x=6\ny=7\nprint(x+y)")
> 13
>
> 
> That seems to work. Again, if I copied and pasted the same as three lines,
> it fails.

Without knowing the system you are using, and how you copy and paste, it 
is hard to comment except to say "Works for me". Here are three lines:

x = 6
y = 7
print(x + y)


If I select those three lines with the mouse, copy, then paste into a 
standard Python interactive interpreter, I get this:


py> x = 6
py> y = 7
py> print(x + y)
13


exactly as expected. But if I do it in IDLE, I get this:

>>> x = 6
y = 7
print(x + y)

SyntaxError: multiple statements found while compiling a single 
statement
>>> 

That *really* sounds like a bug to me. But perhaps I just don't 
understand IDLE.




-- 
Steve
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