simple-cli

Building Ruby CLIs with easy.

Philosophy

Building a command line could be much easier than what ruby provides with its standard library. In general, between the invocation of a tool from the command line and the actual running of whatever code the user intends to run really should disappear.

Ideally a developer would only have to build the implementation of whatever logic should be provided by the tool; everything else - parsing arguments, calling the tool's implementation, printing help - should happen automatically.

This is roughly what sinmple-sql provides.

On versions

simple-cli is still on a 0.x.x version, and, generally, a 0.x.y version is not compatible with a 0.x+1.y version.

These are the follow

• The 0.2.x versions are tracked in the stable branch
• The 0.3.x versions are tracked in the master branch

Basic features

• build command line features in a number of modules;
• public methods in these modules provide a subcommand for the CLI;
• "_" in the method name are being mapped to ":" in the CLI;
• CLI provides a help subcommand. help texts are derived from the methods over a subcommand implementation:
  • The first line determines the "short help" message, to be included in the $CMD help command list;
  • The remaining lines determines the full help message, to be included in the $CMD help subcommand message.

Example

An example can be found in ./doc/examples/ex1

Use logging

Simple::CLI provides a logger instance. This is configured to write to STDERR, and to use colors for different log levels. By default the logger is configured to run on INFO log levels. With the --quiet flag the logger is running at WARN log level; the --verbose command line flag runs the logger on DEBUG log level, and also includes the source position of calling log.

Updating to version 0.3

While the 0.2 version is still perfectly functional, its last version was released on Jul 5th, 2019. Development on the 0.3 versions started with some refactoring: the logic that inspects a subcommand invocation and determines its argument names and default types has been moved to a `simple-services' gem.

To upgrade from simple-cli version 0.2 to version 0.3 all you typically have to do is to replace the

YourApp::CLI.run!(*ARGV)

invocation with

Simple::CLI.run!(YourApp::CLI)

This commit provides an example of doing that.