```
Python 3.4.3 (default, Jan  5 2016, 23:13:10)
[GCC 4.7.3] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import re
>>> for n in range(198, 201):
...     print(re.compile('x' * n))
...
re.compile('xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx')
re.compile('xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx)
re.compile('xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx)
```

The closing quote in the repr goes away once the regex exceeds a certain length. This smells like an off-by-one somewhere that results in the last character to be lost. In any case, it's pretty ugly since the repr clearly pretends to be executable Python code, which is not the case anymore with this quote missing.

It's simply the effect of the "%.200R" format here:
https://hg.python.org/cpython/file/default/Modules/_sre.c#l1417

I recommend not bothering to fix this: it would just be more code, and to what end?

I think it's pretty ugly to have a repr that is valid python code in most cases and suddenly stops being so.

The repr of a string is not truncated, so why truncate it in a pattern object?

With the truncation, why not use a repr style that's clearly not executable to recreate the original object, e.g. `<re pattern %.200R>`

Truncating at 200 characters is actually a common occurrence in the C code, just barely anyone notice this, as it's not common to need more than 200 characters for most expressions.

I don't think this needs to be changed at all; the rare case should not affect the common ones. If eval()'ing your repr fails, you can always access the full regex from `exp.pattern` - which doesn't truncate at 200 characters :)

Not eval'ing it, just wondered why the repr looks so weird when printing an object containing a compiled regex ;)

I'm going to have to agree with ThiefMaster. String literals don't truncate like that, nor do lists, nor tuples.

Are there any similar cases of truncation elsewhere in the standard library?

Yes, the C code pretty much always uses %.<number><format>, in order to
protect itself from buffer overflows. Pulling off an unabbreviated str()
here would be a major piece of work.

Would it be possible to preserve the quotes even in case of truncation?

That would be an interesting exercise. You'd have to patch
PyUnicode_FromFormat(). It would be nice to have this. It should probably
also insert some dots (the universal sign to indicate that something was
truncated).

FTR the repr was added in #13592.

More smart truncating with closing quote and dots was the idea that I want to propose since introducing %R, but I didn't have time to formulate this. Opened issue26090 for this.