github.com/bingoohuang/gg@v0.0.0-20240325092523-45da7dee9335/pkg/cast/README.md (about)

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