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Slop
====
Slop is a simple option parser with an easy to remember syntax and friendly API.
Version 4 of Slop is aimed at Ruby 2.0 or later. Please use
[Version 3](https://github.com/leejarvis/slop/tree/v3) for Ruby 1.9 support.
[](http://travis-ci.org/leejarvis/slop)
Installation
------------
gem install slop
Usage
-----
```ruby
opts = Slop.parse do |o|
o.string '-h', '--host', 'a hostname'
o.integer '--port', 'custom port', default: 80
o.bool '-v', '--verbose', 'enable verbose mode'
o.bool '-q', '--quiet', 'suppress output (quiet mode)'
o.on '--version', 'print the version' do
puts Slop::VERSION
exit
end
end
ARGV #=> -v --host 192.168.0.1
opts[:host] #=> 192.168.0.1
opts.verbose? #=> true
opts.quiet? #=> false
opts.to_hash #=> { host: "192.168.0.1", port: 80, verbose: true, quiet: false }
```
Option types
------------
Built in Option types are as follows:
```ruby
o.string #=> Slop::StringOption, expects an argument
o.bool #=> Slop::BoolOption, no argument, aliased to BooleanOption
o.integer #=> Slop::IntegerOption, expects an argument, aliased to IntOption
o.array #=> Slop::ArrayOption, expects an argument
o.null #=> Slop::NullOption, no argument and ignored from `to_hash`
o.on #=> alias for o.null
```
You can see all built in types in `slop/types.rb`. Suggestions or pull requests
for more types are welcome.
Advanced Usage
--------------
This example is really just to describe how the underlying API works.
It's not necessarily the best way to do it.
```ruby
opts = Slop::Options.new
opts.banner = "usage: connect [options] ..."
opts.separator ""
opts.separator "Connection options:"
opts.string "-H", "--hostname", "a hostname"
opts.int "-p", "--port", "a port", default: 80
opts.separator ""
opts.separator "Extra options:"
opts.array "--files", "a list of files to import"
opts.bool "-v", "--verbose", "enable verbose mode"
parser = Slop::Parser.new(opts)
result = parser.parse(["--hostname", "192.168.0.1"])
result.to_hash #=> { hostname: "192.168.0.1", port: 80,
# files: [], verbose: false }
puts opts # prints out help
```
Arrays
------
Slop has a built in `ArrayOption` for handling array values:
```ruby
opts = Slop.parse do |o|
# the delimiter defaults to ','
o.array '--files', 'a list of files', delimiter: ','
end
# both of these will return o[:files] as ["foo.txt", "bar.rb"]:
# --files foo.txt,bar.rb
# --files foo.txt --files bar.rb
```
Custom option types
-------------------
Slop uses option type classes for every new option added. They default to the
`NullOption`. When you type `o.array` Slop looks for an option called
`Slop::ArrayOption`. This class must contain at least 1 method, `call`. This
method is executed at parse time, and the return value of this method is
used for the option value. We can use this to build custom option types:
```ruby
module Slop
class PathOption < Option
def call(value)
Pathname.new(value)
end
end
end
opts = Slop.parse %w(--path ~/) do |o|
o.path '--path', 'a custom path name'
end
p opts[:path] #=> #<Pathname:~/>
```
Custom options can also implement a `finish` method. This method by default
does nothing, but it's executed once *all* options have been parsed. This
allows us to go back and mutate state without having to rely on options
being parsed in a particular order. Here's an example:
```ruby
module Slop
class FilesOption < ArrayOption
def finish(opts)
if opts.expand?
self.value = value.map { |f| File.expand_path(f) }
end
end
end
end
opts = Slop.parse %w(--files foo.txt,bar.rb -e) do |o|
o.files '--files', 'an array of files'
o.bool '-e', '--expand', 'if used, list of files will be expanded'
end
p opts[:files] #=> ["/full/path/foo.txt", "/full/path/bar.rb"]
```
Errors
------
Slop will raise errors for the following:
* An option used without an argument when it expects one: `Slop::MissingArgument`
* An option used that Slop doesn't know about: `Slop::UnknownOption`
These errors inherit from `Slop::Error`, so you can rescue them all.
Alternatively you can suppress these errors with the `suppress_errors` config
option:
```ruby
opts = Slop.parse suppress_errors: true do
o.string '-name'
end
# or per option:
opts = Slop.parse do
o.string '-host', suppress_errors: true
o.int '-port'
end
```
Printing help
-------------
The return value of `Slop.parse` is a `Slop::Result` which provides a nice
help string to display your options. Just `puts opts` or call `opts.to_s`:
```ruby
opts = Slop.parse do |o|
o.string '-h', '--host', 'hostname'
o.int '-p', '--port', 'port (default: 80)', default: 80
o.string '--username'
o.separator ''
o.separator 'other options:'
o.bool '--quiet', 'suppress output'
o.on '-v', '--version' do
puts "1.1.1"
end
end
puts opts
```
Output:
```
% ruby run.rb
usage: run.rb [options]
-h, --host hostname
-p, --port port (default: 80)
--username
other options:
--quiet suppress output
-v, --version
```
This method takes an optional `prefix` value, which defaults to `" " * 4`:
```
puts opts.to_s(prefix: " ")
```
It'll deal with aligning your descriptions according to the longest option
flag.
Here's an example of adding your own help option:
```ruby
o.on '--help' do
puts o
exit
end
```
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