must's Introduction

"Must" Shortcuts

A trivial package to provide a collection of functions shortcuts error returns to panics.

This is handy when doing small programs, or script-like programs in Go, where any failure should just panic.

It defines:

func M(err error) {
  if err != nil {
    panic(err)
  }
}

func M1[T any](value T, err error) T {
  M(err)
  return value
}

// And similarly it defines functions M2 ... to ... M9.

Example of usage:

package main

import . "github.com/janpfeifer/must"

func main() {
  fName := "my_file.txt"
  contents := M1(os.ReadFile(fName))
  M(os.Remove(fName))
}

Or, if using a Go Jupyter Notebook with GoNB:

import . "github.com/janpfeifer/must"
%%
fName := "my_file.txt"
contents := M1(os.ReadFile(fName))
M(os.Remove(fName))

Notice you can also redefine M, and all other functions will automatically follow suit:

import . "github.com/janpfeifer/must"

func init() {
	M = func(err error) {
	    if err != nil {
		    log.Fatalf("Interrupted with error: %+v", err)	
        }       	
    }
}

%%
contents := M1(os.ReadFile("my_file"))  // This will fail with log.Fatalf if err != nil.

Note

panic is like an exception, and it can be caught (with recover), if you need it at some point in the "script".

FAQ

What if I don't want to panic but do something else ?
See example of reassigning M to however you want errors to be handled.
What if I don't like M as the name for these functions, and want something else ?
If it's something generic, just create an issue, I'll quickly create a subpackage with your favourite naming convention.

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