@mgedmin better syntax errors #105
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This produces tracebacks like the following:
Traceback (most recent call last):
...
File "/home/mg/src/zopefoundation/zc.catalog/.tox/py37/lib/python3.7/site-packages/zope/testbrowser/browser.py", line 1370, in getControlLabels
forlbls = html.select('label[for=%s]' % controlid)
File "/home/mg/src/zopefoundation/zc.catalog/.tox/py37/lib/python3.7/site-packages/bs4/element.py", line 1376, in select
return soupsieve.select(selector, self, namespaces, limit, **kwargs)
File "/home/mg/src/soupsieve/soupsieve/__init__.py", line 108, in select
return compile(select, namespaces, flags).select(tag, limit)
File "/home/mg/src/soupsieve/soupsieve/__init__.py", line 59, in compile
return cp._cached_css_compile(pattern, namespaces, flags)
File "/home/mg/src/soupsieve/soupsieve/css_parser.py", line 192, in _cached_css_compile
CSSParser(pattern, flags).process_selectors(),
File "/home/mg/src/soupsieve/soupsieve/css_parser.py", line 930, in process_selectors
return self.parse_selectors(self.selector_iter(self.pattern), index, flags)
File "/home/mg/src/soupsieve/soupsieve/css_parser.py", line 772, in parse_selectors
key, m = next(iselector)
File "/home/mg/src/soupsieve/soupsieve/css_parser.py", line 917, in selector_iter
raise SelectorSyntaxError(msg, self.pattern)
File "<string>", line 1
label[for=BrowserAdd__zope.catalog.catalog.Catalog]
^
soupsieve.css_parser.SelectorSyntaxError: Malformed attribute selector at position 5
whereas before the traceback ended in
File "/home/mg/src/zopefoundation/zc.catalog/.tox/py37/lib/python3.7/site-packages/soupsieve/css_parser.py", line 881, in selector_iter
raise SyntaxError(msg)
File "<string>", line None
SyntaxError: Malformed attribute selector at position 5
making it difficult to see what exactly was malformed about the selector.
I've also chosen to introduce an exception subclass
(SelectorSyntaxError), so that CSS parse errors could be distinguished
from genuine Python syntax errors.
Compute the line and column positions for multiline selectors. Add unit tests.
Now tracebacks that show a syntax error in a multiline selector will
look right:
File "<string>", line 2
input
[type=3]
^
soupsieve.css_parser.SelectorSyntaxError: Malformed attribute selector at position 9
There's perhaps a slight confusion when the error is not on the last
line, because the caret will be shown after the last line, like this:
File "<string>", line 2
input
[type=3]
[name=foo]
^
soupsieve.css_parser.SelectorSyntaxError: Malformed attribute selector at position 9
I think it's acceptable: if the user pays attention to "line 2", they
can figure it out.
It might be better to change the indentation for the line with the error
to be a little arrow, like this:
File "<string>", line 2
input
--> [type=3]
[name=foo]
^
soupsieve.css_parser.SelectorSyntaxError: Malformed attribute selector at position 9
but I thought that might confuse Python traceback parsers, so I didn't
do it.
…psieve into mgedmin-better-syntax-errors
mgedmin
approved these changes
Feb 6, 2019
soupsieve/util.py
Outdated
| offset = 3 | ||
| text = [] | ||
| for n, line in enumerate(pattern.split('\n'), start=1): | ||
| text.append(('--> {}' if n == self.line else ' {}').format(line)) |
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Suggestion: skip the --> for the (I expect most common) case where pattern is a single-line string
There was a problem hiding this comment.
That's a good idea 👍 .
facelessuser
added
S: approved
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Refactored syntax error work done in pull #103
The big difference here is we take control of the output opposed to relying on
SyntaxError, which was designed for Python syntax errors, to format it for us. In the future (version 2.0) we will most likely derive fromExceptioninstead ofSyntaxError, as it is probably more appropriate for us to not confuse people by deriving fromSyntaxError. This will allow us backwards compatibility for exception detection through the 1.0 series.