SPM - Go

Software Package Metrics tool for Go

Supported metrics:

• Number of files
• Dependencies
• Instability
• Abstractness
• Distance from main sequence

Description of supported metrics

Number of files

The Go source files (go extension) in each package.

Dependencies

Displays the dependencies of each package. SPM-Go classifies the dependencies in three groups:

• Standard dependencies: Dependencies contained in go standard library (e.g. math, fmt, net/http).
• External dependencies: Dependencies imported from external sources (e.g. github.com/spf13/cobra, golang.org/x/tools).
• Internal dependencies: Dependencies contained in the current module.

Instability

The ratio of efferent coupling (Ce) to total coupling (Ce + Ca) such that I = Ce / (Ce + Ca). This metric is an indicator of the package's resilience to change. The range for this metric is 0 to 1, with I=0 indicating a completely stable package and I=1 indicating a completely unstable package. (See: https://en.wikipedia.org/wiki/Software_package_metrics)

SPM-Go uses the following criteria for efferent and afferent coupling:

• Efferent Coupling: Counts only the internal dependencies (packages inside the module)
• Afferent Coupling: Packages inside the module that depends on the current package.

Abstractness

The ratio of the number of abstract classes (and interfaces) in the analyzed package to the total number of classes in the analyzed package. The range for this metric is 0 to 1, with A=0 indicating a completely concrete package and A=1 indicating a completely abstract package. (See: https://en.wikipedia.org/wiki/Software_package_metrics)

As Go doesn't have classes, SPM-Go uses the following criteria for determining the required params to calculate the abstractness:

• Abstractions: Counts structs and interfaces definitions
• Implementations: Counts functions and methods

So the metric formula is: Abstractness = Abstractions/Implementations

Distance from main sequence

The perpendicular distance of a package from the idealized line A + I = 1. D is calculated as D = | A + I - 1 |. This metric is an indicator of the package's balance between abstractness and stability. A package squarely on the main sequence is optimally balanced with respect to its abstractness and stability. Ideal packages are either completely abstract and stable (I=0, A=1) or completely concrete and unstable (I=1, A=0). The range for this metric is 0 to 1, with D=0 indicating a package that is coincident with the main sequence and D=1 indicating a package that is as far from the main sequence as possible. (See: https://en.wikipedia.org/wiki/Software_package_metrics)

Usage

To install spm-go, run

$ go get github.com/fdaines/spm-go

To execute this tool you have to be in the module path

$ cd [path-to-your-module]

Now you can execute Spm-Go tool

$ spm-go command [flags]

Supported commands

Command	Description
packages	Lists packages and number of files
dependencies	Lists dependencies of each package
instability	Analyzes instability of packages
abstractness	Analyzes abstractness of packages
distance	Analyzes distance from the main sequence
all	Displays all metrics for each package

Supported flags

Flag	Description
--format	Specifies the output format for the command. Supported values are: json, console and csv.
--verbose	Includes detailed information while the command is running
--html	Creates an HTML report
--main-package	Allows user to specify the location of the main package, for projects prior to Go 1.11

Examples

$ spm-go all --html
$ spm-go packages
$ spm-go dependencies -v
$ spm-go instability --verbose
$ spm-go abstractness -f csv
$ spm-go distance --format json
$ spm-go all -v -f json
$ spm-gp all -m k8s.io/kubernetes -v

Output Formats

console (Default)

This format uses github.com/jedib0t/go-pretty/v6/table package to print out a formatted table into the console.

+----+-----------------+-------------+
|  # | PACKAGE         | FILES COUNT |
+----+-----------------+-------------+
|  1 | module          |           1 |
|  2 | module/foo      |           9 |
|  3 | module/foo/bar  |           2 |
|  4 | module/utils    |           2 |
+----+-----------------+-------------+

json

{
  "packages": [
    {
      "name": "main",
      "path": "module",
      "files": [
        "main.go"
      ],
      "files_count": 1,
      "dependencies": {
        "standard": [
          "errors",
          "fmt"
        ],
        "internals": [
          "module/utils"
        ],
        "externals": [],
        "standard_count": 2,
        "internals_count": 1,
        "externals_count": 0,
        "count": 3
      },
      "dependants": [
        "module"
      ],
      "afferent_coupling": 0,
      "efferent_coupling": 1,
      "instability": 1,
      "abstractness_details": {
        "functions": 0,
        "methods": 0,
        "interfaces": 0,
        "structs": 0
      },
      "abstractions_count": 0,
      "implementations_count": 0,
      "abstractness": 0,
      "distance": 0
    },
    {
      "name": "utils",
      "path": "module/utils",
      "files": [
        "temporal.go",
        "numeric.go",
        "other.go"
      ],
      "files_count": 3,
      "afferent_coupling": 1,
      "efferent_coupling": 0,
      "instability": 0,
      "abstractness_details": {
        "functions": 0,
        "methods": 0,
        "interfaces": 0,
        "structs": 0
      },
      "dependencies": {
        "standard": [
          "errors",
          "fmt",
          "math"
        ],
        "internals": [],
        "externals": [
          "golang.org/x/tools/go/packages"
        ],
        "standard_count": 3,
        "internals_count": 0, 
        "externals_count": 1,
        "count": 4
      },
      "dependants": [
        "module"
      ],
      "abstractions_count": 0,
      "implementations_count": 0,
      "abstractness": 0,
      "distance": 1
    }
  ]
}

csv

This format uses a semicolon separated format

Package;Files
module;1
module/foo;2
module/foo/bar;3
module/utils;6

HTML Report

If the -html is present, then SPM-Go will create an HTML report into `spm-go/output.html. The report contains data according to the executed command.

Contributions

Feel free to contribute.