is this really a syntax error?

[Skaperen]

if i run this from a file it works as expected. if i type the same code into interactive python, i get a syntax error. which is the mistake? is this really a syntax error?

Output:
lt1a/forums/2 /home/forums 5> cat -n this.py
     1	foo = []
     2	for x in foo:
     3	    print('hi')
     4	print('bye')
lt1a/forums/2 /home/forums 6> python3 this.py
bye
lt1a/forums/2 /home/forums 7> python3
Python 3.8.10 (default, Nov 22 2023, 10:22:35) 
[GCC 9.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> foo = []
>>> for x in foo:
...     print('hi')
... print('bye')
  File "<stdin>", line 3
    print('bye')
    ^
SyntaxError: invalid syntax
>>> print('bar')
bar
>>> 
lt1a/forums/2 /home/forums 8>

[bowlofred]

In the interactive interpreter, if you enter a command that requires continuation information (like an if or a loop), the prompt changes to the secondary prompt ....

You have to exit that mode (by entering a blank line) before entering a new command.

[Skaperen]

so what did it think was a syntax error?

[deanhystad]

I expected an indentation error, but a little experiment shows you only get that for the line immediately following for/if. Indentation errors for the second line are reported as syntax errors.

For the interactive interpreter it is a syntax error. As mentioned by bowlofred, the ... prompt tells you that you are in the body following the for statement. Enter an empty line to get the >>> prompt.

[snippsat]

If use a better interactive interpreter like eg Ipython or ptpython(my favorite) it will work.

foo = []
for x in foo:
    print('hi')
print('bye')

Same copy of code over into the 3 interactive interpreter.

C:\code
λ ipython
Python 3.12.2 (tags/v3.12.2:6abddd9, Feb  6 2024, 21:26:36) [MSC v.1937 64 bit (AMD64)]
Type 'copyright', 'credits' or 'license' for more information
IPython 8.24.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: foo = []
   ...: for x in foo:
   ...:     print('hi')
   ...: print('bye')
bye
In [2]: exit()

C:\code
λ ptpython
>>> foo = []
... for x in foo:
...     print('hi')
... print('bye')
bye
>>> exit()

# With the stander one it failes
C:\code
λ python
Python 3.12.2 (tags/v3.12.2:6abddd9, Feb  6 2024, 21:26:36) [MSC v.1937 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> foo = []
>>> for x in foo:
...     print('hi')
... print('bye')
  File "<stdin>", line 3
    print('bye')
    ^^^^^
SyntaxError: invalid syntax
>>>