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1 cast |
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2 ==== |
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3 [](https://godoc.org/github.com/spf13/cast) |
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4 [](https://travis-ci.org/spf13/cast) |
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5 [](https://goreportcard.com/report/github.com/spf13/cast) |
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6 |
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7 Easy and safe casting from one type to another in Go |
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8 |
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9 Don’t Panic! ... Cast |
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10 |
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11 ## What is Cast? |
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12 |
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13 Cast is a library to convert between different go types in a consistent and easy way. |
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14 |
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15 Cast provides simple functions to easily convert a number to a string, an |
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16 interface into a bool, etc. Cast does this intelligently when an obvious |
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17 conversion is possible. It doesn’t make any attempts to guess what you meant, |
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18 for example you can only convert a string to an int when it is a string |
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19 representation of an int such as “8”. Cast was developed for use in |
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20 [Hugo](http://hugo.spf13.com), a website engine which uses YAML, TOML or JSON |
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21 for meta data. |
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22 |
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23 ## Why use Cast? |
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24 |
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25 When working with dynamic data in Go you often need to cast or convert the data |
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26 from one type into another. Cast goes beyond just using type assertion (though |
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27 it uses that when possible) to provide a very straightforward and convenient |
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28 library. |
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29 |
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30 If you are working with interfaces to handle things like dynamic content |
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31 you’ll need an easy way to convert an interface into a given type. This |
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32 is the library for you. |
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33 |
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34 If you are taking in data from YAML, TOML or JSON or other formats which lack |
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35 full types, then Cast is the library for you. |
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36 |
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37 ## Usage |
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38 |
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39 Cast provides a handful of To_____ methods. These methods will always return |
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40 the desired type. **If input is provided that will not convert to that type, the |
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41 0 or nil value for that type will be returned**. |
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42 |
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43 Cast also provides identical methods To_____E. These return the same result as |
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44 the To_____ methods, plus an additional error which tells you if it successfully |
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45 converted. Using these methods you can tell the difference between when the |
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46 input matched the zero value or when the conversion failed and the zero value |
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47 was returned. |
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48 |
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49 The following examples are merely a sample of what is available. Please review |
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50 the code for a complete set. |
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51 |
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52 ### Example ‘ToString’: |
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53 |
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54 cast.ToString("mayonegg") // "mayonegg" |
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55 cast.ToString(8) // "8" |
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56 cast.ToString(8.31) // "8.31" |
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57 cast.ToString([]byte("one time")) // "one time" |
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58 cast.ToString(nil) // "" |
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59 |
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60 var foo interface{} = "one more time" |
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61 cast.ToString(foo) // "one more time" |
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62 |
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63 |
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64 ### Example ‘ToInt’: |
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65 |
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66 cast.ToInt(8) // 8 |
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67 cast.ToInt(8.31) // 8 |
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68 cast.ToInt("8") // 8 |
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69 cast.ToInt(true) // 1 |
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70 cast.ToInt(false) // 0 |
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71 |
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72 var eight interface{} = 8 |
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73 cast.ToInt(eight) // 8 |
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74 cast.ToInt(nil) // 0 |
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75 |