go-spew/README.md

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go-spew
=======
Go-spew implements a deep pretty printer for Go data structures to aid in
debugging. A comprehensive suite of tests with 100% test coverage is provided
to ensure proper functionality. See `test_coverage.txt` for the gocov coverage
report. Go-spew is licensed under the liberal ISC license, so it may be used in
open source or commercial projects.
If you're interested in reading about how this package came to life and some
of the challenges involved in providing a deep pretty printer, there is a blog
post about it
[here](https://blog.cyphertite.com/go-spew-a-journey-into-dumping-go-data-structures/).
## Documentation
Full `go doc` style documentation for the project can be viewed online without
installing this package by using the excellent GoDoc site here:
http://godoc.org/github.com/davecgh/go-spew/spew
You can also view the documentation locally once the package is installed with
the `godoc` tool by running `godoc -http=":6060"` and pointing your browser to
http://localhost:6060/pkg/github.com/davecgh/go-spew/spew
## Installation
```bash
$ go get github.com/davecgh/go-spew/spew
```
## Quick Start
To dump a variable with full newlines, indentation, type, and pointer
information use Dump or Fdump:
```Go
spew.Dump(myVar1, myVar2, ...)
spew.Fdump(someWriter, myVar1, myVar2, ...)
```
Alternatively, if you would prefer to use format strings with a compacted inline
printing style, use the convenience wrappers Printf, Fprintf, etc with %v (most
compact), %+v (adds pointer addresses), %#v (adds types), or %#+v (adds types
and pointer addresses):
```Go
spew.Printf("myVar1: %v -- myVar2: %+v", myVar1, myVar2)
spew.Printf("myVar3: %#v -- myVar4: %#+v", myVar3, myVar4)
spew.Fprintf(someWriter, "myVar1: %v -- myVar2: %+v", myVar1, myVar2)
spew.Fprintf(someWriter, "myVar3: %#v -- myVar4: %#+v", myVar3, myVar4)
```
## Sample Dump Output
```
(main.Foo) {
unexportedField: (*main.Bar)(0xf84002e210)({
flag: (main.Flag) flagTwo,
data: (uintptr) <nil>
}),
ExportedField: (map[interface {}]interface {}) {
(string) "one": (bool) true
}
}
([]uint8) {
00000000 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f 20 |............... |
00000010 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f 30 |!"#$%&'()*+,-./0|
00000020 31 32 |12|
}
```
## Sample Formatter Output
Double pointer to a uint8:
```
%v: <**>5
%+v: <**>(0xf8400420d0->0xf8400420c8)5
%#v: (**uint8)5
%#+v: (**uint8)(0xf8400420d0->0xf8400420c8)5
```
Pointer to circular struct with a uint8 field and a pointer to itself:
```
%v: <*>{1 <*><shown>}
%+v: <*>(0xf84003e260){ui8:1 c:<*>(0xf84003e260)<shown>}
%#v: (*main.circular){ui8:(uint8)1 c:(*main.circular)<shown>}
%#+v: (*main.circular)(0xf84003e260){ui8:(uint8)1 c:(*main.circular)(0xf84003e260)<shown>}
```
## Configuration Options
Configuration of spew is handled by fields in the ConfigState type. For
convenience, all of the top-level functions use a global state available via the
spew.Config global.
It is also possible to create a ConfigState instance that provides methods
equivalent to the top-level functions. This allows concurrent configuration
options. See the ConfigState documentation for more details.
```
* Indent
String to use for each indentation level for Dump functions.
It is a single space by default. A popular alternative is "\t".
* MaxDepth
Maximum number of levels to descend into nested data structures.
There is no limit by default.
* DisableMethods
Disables invocation of error and Stringer interface methods.
Method invocation is enabled by default.
* DisablePointerMethods
Disables invocation of error and Stringer interface methods on types
which only accept pointer receivers from non-pointer variables.
Pointer method invocation is enabled by default.
* ContinueOnMethod
Enables recursion into types after invoking error and Stringer interface
methods. Recursion after method invocation is disabled by default.
```
## License
Go-spew is licensed under the liberal ISC License.