Idea: add a .forEach method to each ShellString

This would be good to add, allowing users to iterate over the stdout from a command.

This can be done in Bash by running:

for k in $(cat package.json); do # wrap each word in <> brackets and print on a new line
  echo "<$k>"
done

# Or you can change IFS (internal field separator) to break on newlines
IFS='
'
for k in $(cat package.json); do # indent each line of the output
  echo "  $k"
done

A possible API would look like:

ls().forEach(function (file) { // this already works for ls()
  echo('This is a file: ' + file);
});

// something similar could work for cat(), grep(), etc.
cat('file1.txt').forEach(function (line) {
  echo('> ' + line); // put '> ' in front of each line
});

Alternatives would be to iterate over each word (delimited by whitespace) (this is similar to bash’s default behavior, which is sometimes useful).

We could also consider adding the ability to pass an option to .forEach that specifies how the output is split:

var wordCount = 0;
cat('file.txt').forEach(function (a) { wordCount++; }, {split: 'word'});
console.log(wordCount);

TODO:

• Decide if this feature is worth adding
• Decide if we should allow the {split: ...} option
• Figure out a sensible default behavior when the {split: ...} option is not specified (I think “iterate over lines” and “iterate over words” are the two most sensible choices, but I’m open to other suggestions).

[nfischer]

I like the option at the end, just because it’s more consistent with things like exec().

Also, in the interest of making things more bash-like, it might be better to have things like:

// split is every value you want to count as a separator, similar to Bash's IFS var
cat('file.txt').forEach(function (a) { wordCount++; }, { split: ' ' });
cat('file.txt').forEach(function (a) { lineCount++; }, { split: '\n' });

Bash of course treats the actual separator as IFS+ (one or more of any combination of values in the IFS set)

# mixing \n, <SP>, and \t still count as 1 separator
$ for k in $(echo -e 'foo\n \tbar'); do echo "$k"; done
foo
bar

Here’s what I’m thinking some JS-equivalent behavior would look like:

> 'foo\n \tbar'.split(/[\n \t]+/) // we probably want behavior similar to this
[ 'foo', 'bar' ]
> 'foo\n \tbar'.split(/[\n \t]/) // this isn't what we would want by default
[ 'foo', '', '', 'bar' ]

Then we can add in options to get non-bash behavior that people may find useful (like the ability to iterate over empty lines, and stuff like that)

[ariporad]

My $0.02:

1. Great Idea
2. Yes, allow a split option
3. Default to lines