29

This piece of code, file test.py,

if 1:
   print "foo"
print "bar"

can be successfully executed with execfile("test.py") or python test.py, but when one tries to copy-paste it into a Python interpreter:

File "<stdin>", line 3
print "bar"
        ^
SyntaxError: invalid syntax

Why is it so? Can the interpreter by configured in such a way that it would read copy-pasted text successfully?

I guess that may affect typing in the interpreter, but that's OK for me.

4
  • 3
    +1: I've been caught out by missing the line break after a block many times and never found a satisfactory explanation as to why it's different to a non-interactive session. Commented Oct 10, 2011 at 12:07
  • 1
    that's the thing, actually this is my style of working with python right now, and because of this i need to put empty lines in the source files which i'm working on (and testing via copy-paste)... that's irritating Commented Oct 10, 2011 at 12:43
  • The buried question is "Can the interpreter by configured in such a way that it would read copy-pasted text successfully (and not falsely error out on missing newlines breaking indentation, on code which works fine when executed from file)?" I suggest you hoist the actual question to the top. Commented Dec 19, 2023 at 21:43
  • Cannot reopen this, but I believe the right answer without using iPython or weird artifacts is using the F3 command in the standard Python console: github.com/python/cpython/issues/129076#issuecomment-2850549727 Commented Sep 16 at 7:44

9 Answers 9

29

Indentation is probably lost or broken.

Have a look at IPython -- it's an enhanced Python interpreter with many convenient features. One of them is a magic function %paste that allows you to paste multiple lines of code.

It also has tab-completion, auto-indentation... and many more. Have a look at their site.


Using %paste in IPython:

Enter image description here

And copy-and-paste stuff is one of the things fixed in the Qt console. Here's using a plain old copy-and-paste of your code block that "just works" in the new IPython qtconsole:

Enter image description here

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8 Comments

ipython, good as it is, barfs on this sample too: SyntaxError: invalid syntax. Try it!
@Johnsyweb I'm at windows ATM and %paste doesn't seem to work at all (something with tkinter_clipboard). So I can't really try it. But the %cpaste mentioned in @naufraghi's answer works fine even with this example.
@Johnsyweb Works for me, see examples added in my edit. However, I have a pretty recent build of ipython and I'm aware this is something that was definitely b0rked in the past.
Please note that this does not "allow you to paste", this is apparently supposed to grab code from the selection (or maybe the clipboard) and run it automagically, while %cpaste, suggested in another answer, effectively allows you to paste manually.
For multi-line paste, there is also DreamPie for Linux and Windows.
|
20

I don't know any trick for the standard command prompt, but I can suggest you a more advanced interpreter like IPython that has a special syntax for multi-line paste:

In [1]: %cpaste
Pasting code; enter '--' alone on the line to stop.
:for c in range(3):
:    print c
:
:--
0
1
2

Another option is the bpython interpreter that has an automatic paste mode (if you are typing too fast to be an human):

>>> for c in range(3):
...     print c
...
0
1
2
>>>
 <C-r> Rewind  <C-s> Save  <F8> Pastebin  <F9> Pager  <F2> Show Source

1 Comment

Does not work for the example above, perhaps for the reason pointed by @Johnsyweb
11

Do %autoindent to make automatic indentation off. After that, you can paste your code in IPython.

1 Comment

With ipython --no-autoindent it will be off initially.
8

Continuation lines are needed when entering a multi-line construct. --Interactive mode, The Python Tutorial (v2) (v3)

So you need to enter:

if 1:
   print "foo"

print "bar"

I've yet to find a suitable explanation as to why it's different to a non-interactive session, alas.

5 Comments

yes, i've noticed this, but copy-paste testing of my sources is my python work-style right now and this thing imposes on me to put redundant empty lines everywhere...
It's curious, as — IMHO — one would expect text run using shebang lines to run sligthlty in the same way as if it were sent to the stdin of the interpreter.
@Johnsyweb - unit tests are a way to go, but sometimes you work with legacy systems that are hard to unit test, or with infrastructure that runs on older Python versions without unit test support (like wlst scripts that run on jython 2.2.)
This is the solution without using any tool like IPython (although I think that's a very good tool)
This and vic's are the correct answer.
5

All of the current answers suggest you change to IPython. For a Python-only solution, you can use textwrap to remove leading whitespace from lines.

For example,

>>> code="""    x='your pasted code'
                y='with common indentation'"""
>>> formatted=textwrap.dedent(code)
>>> exec(formatted)

2 Comments

You can skip the dedent call if you just add a new line after code='''
But the problem highlighted in the question is not about unexpected leading whitespace. It's about the need for a blank line after completing an indented block.
4

If the pasted content has any empty lines, the interpreter triggers evaluation when encountering them. If any line after an empty line has indentation, it will cause an IndentationError since any previous context has been closed.

Solutions:

  • Delete any empty lines before copying to clipboard.
  • Add any amount of indentation to empty lines (doesn't need to match code) before copying to clipboard.

Note that spaces vs. tabs does not seem to matter.

1 Comment

This solved it for me. I wonder if we can fix this issue (feature) so that we need not remove empty lines from a paste. Perhaps by making it an option in the interpreter github.com/python/cpython
1

If you are like me and use Notepad++ (to copy and paste from), try to replace tabs by spaces by going to menu SettingsPreferencesLanguage and check the replace by spaces.

I had this problem myself for so long and I found out that python.exe recognizes spaces.

2 Comments

But that will only be for content added after that time, not existing content?
Key is "replace tabs by spaces". This works for any editor.
-1
exec(pyperclip.paste())

provided you don't mind using exec. Any other third party clipboard package than pyperclip will do I guess.

1 Comment

The problem is not about how to paste the code. The problem is caused by what was pasted.
-2

One other solution I recently found for a similar problem:

$ python << EOF
if 1:
   print "foo"
print "bar"

EOF

1 Comment

This is NOT pasting into python

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