file-context: for when you are lost in a file
Sometimes I will edit a huge file and got confused or distracted and lose track of where in the file I am. I wrote a tool a few days ago and integrated it into vim. It’s pretty cool.
🔗 Inspiration
One of the subtle brilliances that git provides is context other than simple
line numbers in diffs. I know that it wasn’t the first tool to implement such a
feature (diff -p does the same thing) but it was the first one that I’ve seen
use it by default. For example, the diff
here
includes the following snippet:
@@ -33,9 +44,9 @@ sub _defaults {
my ($self, $params) = @_;
$params->{namespace} ||= [ get_namespace_parts($self) ]->[0];
- $params->{left_method} ||= String::CamelCase::decamelize($params->{left_class});
- $params->{right_method} ||= String::CamelCase::decamelize($params->{right_class});
- $params->{self_method} ||= String::CamelCase::decamelize($self);
+ $params->{left_method} ||= $decamelize->($params->{left_class});
+ $params->{right_method} ||= $decamelize->($params->{right_class});
+ $params->{self_method} ||= $decamelize->($self);
$params->{left_method_plural} ||= $self->_pluralize($params->{left_method});
$params->{right_method_plural} ||= $self->_pluralize($params->{right_method});
$params->{self_method_plural} ||= $self->_pluralize($params->{self_method});
The top of the snippet is the function that the change was made in. The context is not always perfect, but it’s right so often it is astounding. This is exactly what I wanted, but generalized.
🔗 file-context
So I write
file-context.
Here’s the entirety of the code at this time of writing:
#!/bin/dash
if [ $# -ne 2 ]; then
echo "Usage: $0 path/to/file linenumber" 1>&2
exit 1
fi
file="$1"
line="$2"
newfile="/run/shm/$(basename "$file").munged"
cp "$file" "$newfile"
echo "$line\ni\ntmp\n.\nwq" | ed -s "$newfile" >/dev/null
git diff --no-index "$file" "$newfile" |
perl -pne 'if (m/^@@ .* @@ (.*)/) { $_ = "$1\n"} else { undef $_ }'
rm "$newfile"
# vim: ft=sh
Basically all it does is insert the string tmp at the passed line number, does
a git diff, and prints out the context that git prints. I am delighted by
how simple and brief the code is.
Vim integration
I wanted a way to ask vim where I was, so I defined a command called
:Lost
that would call file-context. Here it is:
function Lost()
let line = line('.')
let file = expand('%')
exe 'echom system("file-context ' . file . ' ' . line . '")'
endfunction
command Lost call Lost()
So when you call this the output of file-context gets placed in a single line
at the bottom of your vim window. The only thing that would be more natural is
if it automatically got placed there when I paused, but that might get annoying.
I enjoyed building this tool, and will be interested to find out how useful it is in the future, and what tweaks might be needed. The best part was, as sometimes happens when you have been doing something for a long time, how effortless this was. The only hard part was reading the git source to see if maybe I could get the context more directly, and deciding I couldn’t.
(The following includes affiliate links.)
As with the last post about writing tools, I want to mention The
Unix Programming Environment
For the Vim integration it might be worth looking at Learning
the vi and Vim Editors
Second, if you really want to up your editing game, check out
Practical Vim
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