Is VIM omni-completion really so limited? Or am I missing something?

Ruby:

file = File.new("some.txt", "r")
lines = file.readlines

Omni-completion tests

file.readl
   ---------
   readline     <- PASSED
   readlines
   ---------

"hola".capital
   ---------
   capitalize   <- PASSED
   capitalize!
   ---------

lines.
                <-- FAILED (no suggestions)

lines[0].capital
                <-- FAILED (no suggestions)

I tried Python as well, and it worked in similar way. So it looks like omni-completion can't be used for real development, as it fails on pretty simple cases?

Am I missing some thing? May be the intellisense can be improved some how for Ruby/Python?

Solution

The issue is that Vim does not know if line is a String, an Array or some other Class. There is no deep syntactical analysis in Vim. Vim has no idea of scope, if a variable or method has been defined, etc.

It is only suggesting similar words. So yes, Vim is more limited than an IDE in this aspect. This is also why Eclipse can suggest errors as you typed them, and Vim can't.

Vim is much more basic: in a way, everything is text, and not necessarily seen as "code".

So you are right this is one of Vim limitation.

There are some plugins to work around those limitations (omnicpp is using ctags to determine the scope of some methods) but they are often developed on a per-language basis and there is no silver bullet.