github.com/intel/tfortools

Templates for Tools

Package tfortools provides a set of functions that are designed to make it easier for developers to add template based scripting to their command line tools.

Command line tools written in Go often allow users to specify a template script to tailor the output of the tool to their specific needs. This can be useful both when visually inspecting the data and also when invoking command line tools in scripts. The best example of this is go list which allows users to pass a template script to extract interesting information about Go packages. For example,

go list -f '{{range .Imports}}{{println .}}{{end}}'

prints all the imports of the current package.

The aim of this package is to make it easier for developers to add template scripting support to their tools and easier for users of these tools to extract the information they need. It does this by augmenting the templating language provided by the standard library package text/template in two ways:

• It auto generates descriptions of the data structures passed as input to a template script for use in help messages. This ensures that help usage information is always up to date with the source code.

• It provides a suite of convenience functions to make it easy for script writers to extract the data they need. There are functions for sorting, selecting rows and columns and generating nicely formatted tables.

For example, if a program passed a slice of structs containing stock data to a template script, we could use the following script to extract the names of the 3 stocks with the highest trade volume.

{{table (cols (head (sort . "Volume" "dsc") 3) "Name" "Volume")}}

The output might look something like this:

Name              Volume
Happy Enterprises 6395624278
Big Company       7500000
Medium Company    300122

The functions head, sort, tables and col are provided by this package.