Patterns for error messages

Ruby
1

Hello all.

It seems that the question relates to interpreter “internals”, but I’m
afraid of ask silly questions in ruby-core.

The question is: why error messages of interpreter has inconsistent
addressing system of file and line?

There are at many slightly different schemes (and all of them can be
present
in the same error backtrace):

path/file.rb:10: error text
path/file.rb:1:in require': other-path/other-file.rb:31: error text path/file.rb:7:inmethod’ error text
^ from path/file.rb:12

And so on. I can’t invent one regexp for my output-capturing text editor
(EditPlus on Windows) for catch all cases and automatically extract file
and
path for navigate me to this path.

Thanks for the answers.

v.

2

Alle Saturday 01 March 2008, Victor ‘Zverok’ Shepelev ha scritto:

v.

I can’t find the differences. If you want a regexp which gives the name
of the
file, I think you can simply use something like:

/^.*(?=:\d+:)/

Stefano

3

and path for navigate me to this path.

For 4 of my cases it would find, respectively:

  1. path/file.rb:10: - OK
  2. path/file.rb:1: - when I wanted “the real error” address -
    “other-path/other-file.rb:31:”
  3. path/file.rb:7: - OK
  4. nothing, because of there’s no last “:” in the string with “^ from”.
    Even
    if you delete last “:” from regexp, the result will be unsatisfactory: "
    ^
    from path/file.rb:12" (There would be even more spaces, but you
    understand
    the idea)

It’s a pain.

V.

4

Alle Monday 03 March 2008, Victor ‘Zverok’ Shepelev ha scritto:

and path for navigate me to this path.

It’s a pain.

V.

Yes, now I see what you mean. Well, for the second case, it depends on
how
your editor works exactly. If it has support for regexp groups, you can
use
the following regexp:

/^(?:.:\d+:in\s+`require’:\s+)?(.)(?=:\d+:)/

The name of the file is in the first group (this works also for the
first
case)

Regarding the last case, I think (but I may be wrong) that the third and
last
one are a single message, split in two lines for some reason. You should
try
to understand why this happens and act consequently. If you post the
full
error messages, maybe with a piece of code which generates them, I can
try to
help you more.

Stefano

5

From: Stefano C. [mailto:[email protected]]
Sent: Monday, March 03, 2008 10:42 AM

The question is: why error messages of interpreter has inconsistent
And so on. I can’t invent one regexp for my output-capturing text
of

  1. nothing, because of there’s no last “:” in the string with “^ from”.
    your editor works exactly. If it has support for regexp groups, you can use
    the following regexp:

/^(?:.:\d+:in\s+`require’:\s+)?(.)(?=:\d+:)/

The name of the file is in the first group (this works also for the first
case)

OK, but this regexp works for the second case ONLY (unfortunately, I
have
only one “output pattern” setting, so, I am trying to invent the
universal
one).

Regarding the last case, I think (but I may be wrong) that the third and
last
one are a single message, split in two lines for some reason. You should
try
to understand why this happens and act consequently. If you post the full
error messages, maybe with a piece of code which generates them, I can try
to
help you more.

Yes, it is like call stack: first line has something like case1-case3,
other
lines has something like case4.

For ex:

D:/!work/home/!stuff/ruby-tricks/test.rb:1:in `require’: ./tricks.rb:31:
syntax error, unexpected ‘]’, expecting $end (SyntaxError)
p 1,2,3].inject(0){|sum, n| sum + n}
^ from D:/!work/home/!stuff/ruby-tricks/test.rb:1

And I’d be happy to browse all call-stack by clicking on output strings
in
“Script Output” window of my editor.

Most of compilers have “parsing-friendly” output, having the same
“file:line: error” strings on each line.

Faithfully, I have a proposition to core team for thinking about it.

V.

6

From: Stefano C. [mailto:[email protected]]
Sent: Monday, March 03, 2008 11:41 AM

help you more.
^ from D:/!work/home/!stuff/ruby-tricks/test.rb:1

This should take care of all the four patterns:

/^(?:.:\d+:in\s+`require’:\s+|\s+^\s+from\s+)?(.)(?=:\d+)/

But not this one:

“./…/app/models/teachers.rb:7:in `initialize’: undefined local
variable”

(not saying about that most of regexp engines too dumb for doing ?: and
?=
groups).

Maybe somebody from core team can comment on the question phrased as:
Can
the error messages form be more consistend? (Hmmm… Even I’m ready for
trying to contribute, I think). Or this kind of questions should be
asked in
ruby-core?

V.

7

Alle Monday 03 March 2008, Victor ‘Zverok’ Shepelev ha scritto:

This should take care of all the four patterns:

/^(?:.:\d+:in\s+`require’:\s+|\s+^\s+from\s+)?(.)(?=:\d+)/

But not this one:

“./…/app/models/teachers.rb:7:in `initialize’: undefined local variable”

I think this is a different matter: here, we’re in the first case (the
simplest) and the regexp correctly gives:

“./…/app/models/teachers.rb”

This is the path of the file where the error occurs, relative to the
directory
where ruby was started. What would you like to get here?

(not saying about that most of regexp engines too dumb for doing ?: and ?=
groups).

Are they? I didn’t try many editors (in particular, kate and vim on
linux),
but they all support them. At any rate, I think you can do without them.
If
you replace the initial (?: with a simple (, you’ll get the name of the
file
in the second group instead of the first. The look-ahead at the end can
be
removed by replacing (.) with [^:]. which matche any character except
the
column. This has the side effect of not working with filenames
containing ‘:’
(this is the reason I used the look-ahead).

Stefano

8

Alle Monday 03 March 2008, Victor ‘Zverok’ Shepelev ha scritto:

OK, but this regexp works for the second case ONLY (unfortunately, I have
only one “output pattern” setting, so, I am trying to invent the universal
one).

It should work for all the first three cases (at least, it does in ruby,
which
I’m using to test it).

Yes, it is like call stack: first line has something like case1-case3, other
lines has something like case4.

For ex:

D:/!work/home/!stuff/ruby-tricks/test.rb:1:in `require’: ./tricks.rb:31:
syntax error, unexpected ‘]’, expecting $end (SyntaxError)
p 1,2,3].inject(0){|sum, n| sum + n}
^ from D:/!work/home/!stuff/ruby-tricks/test.rb:1

This should take care of all the four patterns:

/^(?:.:\d+:in\s+`require’:\s+|\s+^\s+from\s+)?(.)(?=:\d+)/

Stefano