https://github.com/muir/reflectutils

Golang utility functions for working with reflection
https://github.com/muir/reflectutils

go golang reflection-library

Last synced: about 1 month ago
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Golang utility functions for working with reflection

• Host: GitHub
• URL: https://github.com/muir/reflectutils
• Owner: muir
• License: mit
• Created: 2021-10-24T05:44:39.000Z (about 3 years ago)
• Default Branch: main
• Last Pushed: 2024-08-23T00:40:06.000Z (4 months ago)
• Last Synced: 2024-08-23T01:53:58.679Z (4 months ago)
• Topics: go, golang, reflection-library
• Language: Go
• Homepage:
• Size: 50.8 KB
• Stars: 7
• Watchers: 1
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

• awesome-go-extra - reflectutils - 10-24T05:44:39Z|2022-04-16T03:56:56Z| (Utilities / Fail injection)

README

        
# reflectutils - utility functions for working with Golang's reflect package

[![GoDoc](https://godoc.org/github.com/muir/reflectutils?status.png)](https://pkg.go.dev/github.com/muir/reflectutils)

![unit tests](https://github.com/muir/reflectutils/actions/workflows/go.yml/badge.svg)

[![report card](https://goreportcard.com/badge/github.com/muir/reflectutils)](https://goreportcard.com/report/github.com/muir/reflectutils)

[![codecov](https://codecov.io/gh/muir/reflectutils/branch/main/graph/badge.svg)](https://codecov.io/gh/muir/reflectutils)

Install:

	go get github.com/muir/reflectutils

---

Reflectutils is simply a repository for functions useful for working with Golang's reflect package.

Here's the highlights:

## Walking structures

```go

func WalkStructElements(t reflect.Type, f func(reflect.StructField) bool)

```

Recursively walking a struct with reflect has a pitfalls: 

1. It isn't recurse with respect to embeded structs

1. The `Index` field of `reflect.Structfield` of embedded structs is not relative to your starting point.

[WalkStructElements()](https://pkg.go.dev/github.com/muir/reflectutils#WalkStructElements) walks 

embedded elements and it updates `StructField.Index` so that it is

relative to the root struct that was passed in.

## Setting elements

```go

func MakeStringSetter(t reflect.Type, optArgs ...StringSetterArg) (func(target reflect.Value, value string) error, error)

```

[MakeStringSetter()](https://pkg.go.dev/github.com/muir/reflectutils#MakeStringSetter) 

returns a function that can be used to assing to `reflect.Value` given a

string value.  It can handle arrays and slices (splits strings on commas).

## Parsing struct tags

Use [SplitTag()](https://pkg.go.dev/github.com/muir/reflectutils#SplitTag) to break a struct

tag into it's elements and then use [Tag.Fill()](https://pkg.go.dev/github.com/muir/reflectutils#Tag.Fill)

to parse it into a struct.

For example:

```go

type TagInfo struct {

	Name	string	`pt:"0"`     // positional, first argument

	Train	bool	`pt:"train"` // boolean: true: "train", "train=true"; false: "!train", "train=false"

	Count	int	`pt:"count"` // integer value will be parsed

}

st := reflect.StructTag(`foo:"bar,!train,count=9"`)

var tagInfo TagInfo

err := GetTag(st, "foo").Fill(&tagInfo)

// tagInfo.Name will be "bar"

// tagInfo.Train will be false

// tagInfo.Count will be 9

```

## Type names

The `TypeName()` function exists to disambiguate between type names that are

versioned.  `reflect.Type.String()` will hides package versions.  This doesn't

matter unless you've, unfortunately, imported multiple versions of the same

package.  

## Default filler

The `FillInDefaultValues()` function will look at for a struct tag named "default"

and use that value to fill in values where no value has been set.

## Development status

Reflectutils is used by several packages.  Backwards compatability is expected.