Are Python commands suitable in Vim's visual mode?

Question

I have found the following command in AWK useful in Vim

:'<,'>!awk '{ print $2 }'

Python may also be useful in Vim. However, I have not found an useful command in Python for Vim's visual mode.

Which Python commands do you use in Vim?

Answer 1

It's hard to make useful one-liner filters in Python. You need to import sys to get stdin, and already you're starting to push it. This isn't to say anything bad about Python. My feeling is that Python is optimized for multi-line scripts, while the languages that do well at one-liners (awk, sed, bash, I could name others but would probably be flamed...) tend work less well (IMHO) when writing scripts of any significant complexity.

I do really like Python for writing multi-line scripts that I can invoke from Vim. For example, I've got one Python script that will, when given a signature for a Java constructor, like this:

Foo(String name, int size) {

will emit a lot of the boilerplate that goes into creating a value class:

private final String name;
private final int size;

public String getName() {
  return name;
}

public int getSize() {
  return size;
}

@Override
public boolean equals(Object that) {
  return this == that
      || (that instanceof Foo && equals((Foo) that));
}

public boolean equals(Foo that) {
  return Objects.equal(getName(), that.getName())
      && this.getSize() == that.getSize();
}

@Override
public int hashCode() {
  return Objects.hashCode(
      getName(),
      getSize());
}

Foo(String name, int size) {
  this.name = Preconditions.checkNotNull(name);
  this.size = size;

I use this from Vim by highlighting the signature and then typing !jhelper.py.

I also used to use Python scripts I'd written to reverse characters in lines and to reverse the lines of a file before I found out about rev and tac.

Answer 2

Python is most useful with vim when used to code vim "macros" (you need a vim compiled with +python, but many pre-built ones come that way). Here is a nice presentation about some of the things you can do with (plenty of examples and snippets!), and here are vim's own reference docs about this feature.