author | Mikael Berthe <mikael@lilotux.net> |
Sat, 29 Sep 2018 18:09:54 +0200 | |
changeset 242 | 2a9ec03fe5a1 |
child 260 | 445e01aede7e |
permissions | -rw-r--r-- |
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cast |
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==== |
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[![GoDoc](https://godoc.org/github.com/spf13/cast?status.svg)](https://godoc.org/github.com/spf13/cast) |
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[![Build Status](https://api.travis-ci.org/spf13/cast.svg?branch=master)](https://travis-ci.org/spf13/cast) |
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[![Go Report Card](https://goreportcard.com/badge/github.com/spf13/cast)](https://goreportcard.com/report/github.com/spf13/cast) |
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Easy and safe casting from one type to another in Go |
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Don’t Panic! ... Cast |
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## What is Cast? |
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Cast is a library to convert between different go types in a consistent and easy way. |
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Cast provides simple functions to easily convert a number to a string, an |
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interface into a bool, etc. Cast does this intelligently when an obvious |
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conversion is possible. It doesn’t make any attempts to guess what you meant, |
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for example you can only convert a string to an int when it is a string |
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representation of an int such as “8”. Cast was developed for use in |
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[Hugo](http://hugo.spf13.com), a website engine which uses YAML, TOML or JSON |
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for meta data. |
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## Why use Cast? |
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When working with dynamic data in Go you often need to cast or convert the data |
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from one type into another. Cast goes beyond just using type assertion (though |
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it uses that when possible) to provide a very straightforward and convenient |
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library. |
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If you are working with interfaces to handle things like dynamic content |
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you’ll need an easy way to convert an interface into a given type. This |
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is the library for you. |
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If you are taking in data from YAML, TOML or JSON or other formats which lack |
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full types, then Cast is the library for you. |
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## Usage |
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Cast provides a handful of To_____ methods. These methods will always return |
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the desired type. **If input is provided that will not convert to that type, the |
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0 or nil value for that type will be returned**. |
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Cast also provides identical methods To_____E. These return the same result as |
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the To_____ methods, plus an additional error which tells you if it successfully |
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converted. Using these methods you can tell the difference between when the |
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input matched the zero value or when the conversion failed and the zero value |
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was returned. |
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The following examples are merely a sample of what is available. Please review |
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the code for a complete set. |
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### Example ‘ToString’: |
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cast.ToString("mayonegg") // "mayonegg" |
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cast.ToString(8) // "8" |
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cast.ToString(8.31) // "8.31" |
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cast.ToString([]byte("one time")) // "one time" |
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cast.ToString(nil) // "" |
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var foo interface{} = "one more time" |
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cast.ToString(foo) // "one more time" |
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### Example ‘ToInt’: |
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cast.ToInt(8) // 8 |
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cast.ToInt(8.31) // 8 |
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cast.ToInt("8") // 8 |
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cast.ToInt(true) // 1 |
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cast.ToInt(false) // 0 |
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var eight interface{} = 8 |
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cast.ToInt(eight) // 8 |
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cast.ToInt(nil) // 0 |
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