gorram

^{_{image: © SubSuid}}

It's like go run for any go function.

Automagically understands how to produce an interface from the command line into a Go function.

Sometimes, magic is just someone spending more time on something than anyone else might reasonably expect. -Teller

Installation

go get npf.io/gorram

Note: gorram depends on having a working go environment to function, since it dynamically analyzes go code in the stdlib and in your GOPATH.

Examples

Pretty print JSON:

$ echo '{ "foo" : "bar" }' | gorram encoding/json Indent "" $'\t'
{
    "foo" : "bar"
}

Calculate a sha256 sum:

$ gorram crypto/sha256 Sum256 foo.gz
abcdef012345678

How it works

The first time you run Gorram with a specific function name, Gorram analyzes the package function and generates a file for use with go run. Gorram intelligently converts stdin and/or cli arguments into arguments for the function. Output is converted similarly to stdout. The code is cached in a local directory so that later runs don't incur the generation overhead.

Heuristics

By default, Gorram just turns CLI args into function args and prints out the return value of a function using fmt's %v. However, there are some special heuristics that it uses to be smarter about inputs and outputs, based on common go idioms.

For example:

usage:
$ cat foo.zip | gorram crypto/sha1 Sum
or
$ gorram crypto/sha1 Sum foo.zip

function:
// crypto/sha1
func Sum(data []byte) [Size]byte

Gorram understands functions that take a single slice of bytes (or an io.Reader) should read from stdin, or if an argument is specified, the argument is treated as a filename to be read.

Return values that are an array of bytes are understood to be intended to be printed with fmt's %x, so that you get 2c37424d58 instead of [44 55 66 77 88].

usage:
$ gorram encoding/json Indent foo.json "" $'\t'
or
$ cat foo.json | gorram encoding/json Indent "" $'\t'

function:
// encoding/json
func Indent(dst *bytes.Buffer, src []byte, prefix, indent string) error

Gorram understands that functions with a src argument that is an io.Reader or []bytes and a dst argument that is a []byte, *bytes.Buffer, or io.Writer will read from stdin (or use an argument as a file to open), and write what is written to dst to stdout.

Gorram understands that if the function returns a non-nil error, the error should be written to stderr, the program exits with a non-zero exit status, and nothing is written to stdout.

Gorram understands that prefix and indent are arguments that need to be specified in the command line.

usage:
$ gorram math Cos 25

function:
// math
func Cos(x float64) float64

Gorram understands how to convert CLI arguments using the stringconv.Parse* functions, and will print outputs with fmt.Printf("%v\n", val).

usage:
$ echo 12345 | gorram encoding/base64 StdEncoding.EncodeToString
MTIzNDU2Cg==

function:
// base64
func (e *Encoding) EncodeToString(b []byte]) string

Gorram understands that packages have global variables that have methods you can call.

Development

See the project page for what's being worked on now.