Highlight simple Python syntax errors

Tip 969 Printable Monobook Previous Next

created August 10, 2005 · complexity basic · author Jon Marshall · version 6.0

---

If you want simple syntax errors highlighted in Python (such as if statements with a missing colon at the end) then do the following:

1. Download and install script#790.

1. Search for the line beginning "syn match pythonError". Add the following lines after that:

syn match pythonError "^\s*def\s\+\w\+(.*)\s*$" display
syn match pythonError "^\s*class\s\+\w\+(.*)\s*$" display
syn match pythonError "^\s*for\s.*[^:]$" display
syn match pythonError "^\s*except\s*$" display
syn match pythonError "^\s*finally\s*$" display
syn match pythonError "^\s*try\s*$" display
syn match pythonError "^\s*else\s*$" display
syn match pythonError "^\s*else\s*[^:].*" display
syn match pythonError "^\s*if\s.*[^\:]$" display
syn match pythonError "^\s*except\s.*[^\:]$" display
syn match pythonError "^\s*while\s.*[^\:]$" display
syn match pythonError "^\s*return\s.*:$" display
syn match pythonError "&&" display
syn match pythonError "||" display
syn match pythonError "[;]$" display
syn keyword pythonError do

Comments

It is a bit too simplistic unfortunately.

Constructions like these will be labeled red on the if line:

if (field_name == 'summary'
  and oldChange['field'] == ticketChange['field']):

---

And so it should highlight that line as there is a syntax error!

Point taken about it being simplistic, hence the 'simple' in the title. I find that

• Such constructs occur relatively infrequently.
• You can avoid by placing a superfluous '\' at the end of the line:

  if (foo \
  and bar)

Not ideal, but I find that I omit the trailing colon so often that I prefer the odd false positive.

---

I also think it's really too simple.

I'm using list comprehension and generator quite often. And than constructs like the following appears regularly. (Yes it's taken from one of my current programs)

lMax = sum(sum(self.getComp(id1, id2, user) * self.getWeight(id2, user)
for id2 in items) / self.getWeight(id1, user)
for id1 in items)

But nevertheless I've simplified it a bit.

syn match pythonError "^\s*\(class\|def\|for\|while\|try\|except\|finally\|if\|elif\|else\)[^\:]*$" display
syn match pythonError "^\s*\(class\|def\|for\|while\|try\|except\|finally\|if\|elif\|else\)$" display
syn match pythonError "&&" display
syn match pythonError "||" display
syn match pythonError "[;]$" display
syn keyword pythonError do

Unfortunately it doesn't work when the line contains no leading spaces.

---

I prefer this version of 'if':

syn match pythonError "^\s*\(if\|elif\)[^:]*$" display

It works with one-line expressions like "if 1: do_something()".

Apart from that, works well for me as I keep forgetting the ":" often. Exactly what I was looking for.

---