On 2019-02-26, Stephan Witt wrote:
> Am 26.02.2019 um 09:06 schrieb Guenter Milde <mi...@users.sf.net>:
>> On 2019-02-26, Stephan Witt wrote:
>>> I’m having a problem with lib/scripts/convertDefault.py and Python 3,
>>> see below:
>>> Traceback (most recent call last):
>>> File "/Users/stephan/git/lyx/lib/scripts/convertDefault.py", line 38, in
>>> <module>
>>> output = output.decode()
>>> AttributeError: 'str' object has no attribute 'decode'
>> ...
>>> Is this to be expected?
...
>> Does the following patch help?
> Yes, of course. But IMO the AttributeError should happen in any case.
I may have misunderstood the backlog. It seems to have not happened for
others, yet.
> Not only on error. Probably it’s a copy-n-paste error… the same
> construct to detect Python 3 is used in unicode_symbols.py and
> lyxpreview2bitmap.py. Probably the code in these files is ok. But it
> would be good if you’d review it.
Yes, there are some other cases where special action for Py2 vs. Py3 is
required. I had a look, the other files seem OK.
However, my "fix" may work (by coincidence) but is not correct:
The next action is to match the `output` string to a regular expression
(given as string-literal, i.e. a unicode-string in Py3 and a
bytes-string in Py2).
With my patch, the `output` is decoded to a unicode-string under Py2.
For the match, it is implicitely re-converted to a bytes-string.
This works (as long as it only contains ASCII chars) but is unnecessary.
I suppose that the unpatched code is correct with older Py3 versions, where
`os.popen()` may have returned a bytes-string but the regexp-match a
unicode-string and no implicit conversion is done.
In this case, a better patch would be:
diff --git a/lib/scripts/convertDefault.py b/lib/scripts/convertDefault.py
index 8678965013..a247ce640a 100644
--- a/lib/scripts/convertDefault.py
+++ b/lib/scripts/convertDefault.py
@@ -35,7 +35,10 @@ if fout.close() != None:
output = fout.readline()
fout.close()
if not PY2:
- output = output.decode()
+ try:
+ output = output.decode()
+ except AttributeError:
+ pass
version = re_version.match(output)
Otherwise the if clause can go alltogether:
--- a/lib/scripts/convertDefault.py
+++ b/lib/scripts/convertDefault.py
@@ -19,8 +19,6 @@
from __future__ import print_function
import os, re, sys
-PY2 = sys.version_info[0] == 2
-
# We may need some extra options only supported by recent convert versions
re_version = re.compile(r'^Version:.*ImageMagick\s*(\d*)\.(\d*)\.(\d*).*$')
# imagemagick 7
@@ -34,8 +32,6 @@ if fout.close() != None:
fout = os.popen('convert -version 2>&1')
output = fout.readline()
fout.close()
-if not PY2:
- output = output.decode()
version = re_version.match(output)
In any case, os.popen is deprecated since Python 2.6 and should be replaced
by calls to subprocess. https://docs.python.org/3/library/subprocess.html
Hope this helps,
Günter
