chapters/20.markdown @ beb0d41a8929

Variable Scoping
================

So far Vimscript's variables may seem familiar if you come from a dynamic
language like Python or Ruby.  For the most part variables act like you would
expect, but Vim adds a certain twist to variables: scoping.

Open two buffers in separate splits, then go into one of then and run the
following commands:

    :::vim
    :let b:hello = "world"
    :echo b:hello

As expected, Vim displays "world".  Now switch to the other buffer and run the
echo command again:

    :::vim
    :echo b:hello

This time Vim throws an error, saying it can't find the variable.

When we used `b:` in the variable name we told Vim that the variable `hello`
should be local to the current buffer.

Vim has many different scopes for variables, but we need to learn a little more
about Vimscript before we can take advantage of the rest.  For now, just
remember that when you see a variable that start with a character and a colon
that it's describing a scoped variable.

Exercises
---------

Skim over the list of scopes in `:help internal-variables`.  Don't worry if you
don't know what some of them mean, just take a look and keep them in the back of
your mind.