Is there a way to compile the Python code ignore syntax?

Question

I am making code that works on both Python 2 and Python 3. But there was no problem in theory, but there was a Python problem.

Now I'm build and use both Python 2.7.5 and Python 3.7.4.

This is part of my code

ex)

if sys.version_info < (3,):
    print(keys),;
    print(values)
else:
    print(keys,'/ ', end='')
    print(values)

This code that checks Python version with sys.version, corresponding 'if' will be working.

But, of course there is a syntax error. Python 2 does not support [end=''].

In my opinion... Even if you actually ignore it and act on it, there's no problem code. I tried 'Try-except', but syntax errors were not ignored.

How can both Python2 and Python3 not change lines while weaving compatible codes?

Adding `from __future__ import print_function` at the top of your script should mean you get Python 3's printing in Python 2, with no need to write the `print`s two different ways — Marius, Jan 17 '20 at 04:01
To explain why Python 2 does not support `print` arguments like `end`: In Python 2 the `print` statement if written with parentheses is considered as `print` with an expression (in case of one item) or a tuple (in case of multiple items). This make it by lucky accident somewhat compatible to Python 3. But `end=''` would not be a valid syntax for a tuple and fails. — Klaus D., Jan 17 '20 at 04:15
Python 2 is dead! You should switch to 3. And, before anyone complains, it's not as if we weren't given plenty of warning. — paxdiablo, Jan 17 '20 at 04:21
@paxdiablo We have a saying in my language: People pronounced dead live the longest. — Klaus D., Jan 17 '20 at 04:34

Shibiraj · Answer 1 · 2020-01-17T07:01:02.663

4

Import the package print_function and try

from __future__ import print_function

edited Jan 17 '20 at 07:01

answered Jan 17 '20 at 04:02

Shibiraj

769
4
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ShadowRanger · Answer 2 · 2020-01-17T04:11:59.277

In this particular case, just get the Python 3 print function in both Python 2 and Python 3 by adding:

from __future__ import print_function

to the very top of your file, then only use the Python 3 syntax.

As for avoiding the SyntaxError from actually incompatible constructs that can't be fixed with a __future__ import, the only solutions are putting the incompatible code in separate modules (a public module can do version testing to import the implementations from the private module appropriate to the Python version), or evaling a string containing the code for the appropriate version (exec won't typically work, because it also changed from keyword statement to built-in function in the transition; eval+compile is the same in both though).

There is no way to just "turn off syntax checking", because invalid syntax definitionally means the parser has encountered an unrecoverable error; you don't want it to try to stumble onwards, guessing at what everything else means in the context of the garbage state it was left in.

Is there a way to compile the Python code ignore syntax?

2 Answers2