golang語言特性

這是一個建立於 的文章，其中的資訊可能已經有所發展或是發生改變。

1.包括的golang特性

1. Godeps
2. vendor
3. _ 底線

2.Godeps

• golang1.1版本之後，有了godep依賴管理工具，項目下新加了Godeps檔案夾，其中含有項目依賴的包，記錄包依賴的檔案為Godeps.json，下面是一個例子，該例子為distribution2.1項目的Godeps，在github.com/docker/distribution可以直接用github.com/spf13/cobra中的結構而不用匯入，可見ImportPath下的包可以直接調用Deps下含有的包：

{    "ImportPath": "github.com/docker/distribution",    "GoVersion": "go1.4.2",    "Packages": [        "./..."    ],    "Deps": [        {            "ImportPath": "github.com/AdRoll/goamz/aws",            "Rev": "aa6e716d710a0c7941cb2075cfbb9661f16d21f1"        },        {            "ImportPath": "github.com/AdRoll/goamz/cloudfront",            "Rev": "aa6e716d710a0c7941cb2075cfbb9661f16d21f1"        },        {            "ImportPath": "github.com/AdRoll/goamz/s3",            "Rev": "aa6e716d710a0c7941cb2075cfbb9661f16d21f1"        },        {            "ImportPath": "github.com/Azure/azure-sdk-for-go/storage",            "Rev": "97d9593768bbbbd316f9c055dfc5f780933cd7fc"        },        {            "ImportPath": "github.com/Sirupsen/logrus",            "Comment": "v0.7.3",            "Rev": "55eb11d21d2a31a3cc93838241d04800f52e823d"        },        {            "ImportPath": "github.com/bugsnag/bugsnag-go",            "Comment": "v1.0.2-5-gb1d1530",            "Rev": "b1d153021fcd90ca3f080db36bec96dc690fb274"        },        {            "ImportPath": "github.com/bugsnag/osext",            "Rev": "0dd3f918b21bec95ace9dc86c7e70266cfc5c702"        },        {            "ImportPath": "github.com/bugsnag/panicwrap",            "Rev": "e5f9854865b9778a45169fc249e99e338d4d6f27"        },        {            "ImportPath": "github.com/denverdino/aliyungo/oss",            "Rev": "0e0f322d0a54b994dea9d32541050d177edf6aa3"        },        {            "ImportPath": "github.com/denverdino/aliyungo/util",            "Rev": "0e0f322d0a54b994dea9d32541050d177edf6aa3"        },        {            "ImportPath": "github.com/docker/docker/pkg/tarsum",            "Comment": "v1.4.1-3932-gb63ec6e",            "Rev": "b63ec6e4b1f6f5c77a6a74a52fcea9564538c575"        },        {            "ImportPath": "github.com/docker/libtrust",            "Rev": "fa567046d9b14f6aa788882a950d69651d230b21"        },        {            "ImportPath": "github.com/garyburd/redigo/internal",            "Rev": "535138d7bcd717d6531c701ef5933d98b1866257"        },        {            "ImportPath": "github.com/garyburd/redigo/redis",            "Rev": "535138d7bcd717d6531c701ef5933d98b1866257"        },        {            "ImportPath": "github.com/gorilla/context",            "Rev": "14f550f51af52180c2eefed15e5fd18d63c0a64a"        },        {            "ImportPath": "github.com/gorilla/handlers",            "Rev": "60c7bfde3e33c201519a200a4507a158cc03a17b"        },        {            "ImportPath": "github.com/gorilla/mux",            "Rev": "e444e69cbd2e2e3e0749a2f3c717cec491552bbf"        },        {            "ImportPath": "github.com/inconshreveable/mousetrap",            "Rev": "76626ae9c91c4f2a10f34cad8ce83ea42c93bb75"        },        {            "ImportPath": "github.com/mitchellh/mapstructure",            "Rev": "482a9fd5fa83e8c4e7817413b80f3eb8feec03ef"        },        {            "ImportPath": "github.com/ncw/swift",            "Rev": "ca8cbbde50d4e12dd8ad70b1bd66589ae98efc5c"        },        {            "ImportPath": "github.com/noahdesu/go-ceph/rados",            "Comment": "v.0.3.0-29-gb15639c",            "Rev": "b15639c44c05368348355229070361395d9152ee"        },        {            "ImportPath": "github.com/spf13/cobra",            "Rev": "312092086bed4968099259622145a0c9ae280064"        },        {            "ImportPath": "github.com/spf13/pflag",            "Rev": "5644820622454e71517561946e3d94b9f9db6842"        },        {            "ImportPath": "github.com/stevvooe/resumable",            "Rev": "51ad44105773cafcbe91927f70ac68e1bf78f8b4"        },        {            "ImportPath": "github.com/yvasiyarov/go-metrics",            "Rev": "57bccd1ccd43f94bb17fdd8bf3007059b802f85e"        },        {            "ImportPath": "github.com/yvasiyarov/gorelic",            "Comment": "v0.0.6-8-ga9bba5b",            "Rev": "a9bba5b9ab508a086f9a12b8c51fab68478e2128"        },        {            "ImportPath": "github.com/yvasiyarov/newrelic_platform_go",            "Rev": "b21fdbd4370f3717f3bbd2bf41c223bc273068e6"        },        {            "ImportPath": "golang.org/x/crypto/bcrypt",            "Rev": "c10c31b5e94b6f7a0283272dc2bb27163dcea24b"        },        {            "ImportPath": "golang.org/x/crypto/blowfish",            "Rev": "c10c31b5e94b6f7a0283272dc2bb27163dcea24b"        },        {            "ImportPath": "golang.org/x/net/context",            "Rev": "1dfe7915deaf3f80b962c163b918868d8a6d8974"        },        {            "ImportPath": "gopkg.in/check.v1",            "Rev": "64131543e7896d5bcc6bd5a76287eb75ea96c673"        },        {            "ImportPath": "gopkg.in/yaml.v2",            "Rev": "bef53efd0c76e49e6de55ead051f886bea7e9420"        }    ]}

3.vendor

• golang1.5版本後加入vendor依賴包管理工具，還在試用階段，需要匯入環境變數export GO15VENDOREXPERIMENT=1，這樣做後就可以直接在編寫go代碼時匯入vendor目錄下的包而不用從gopath開始，比如docker1.9項目中，import “github.com/docker/distribution/digest”匯入的就是vendor目錄下的對應包

4._底線

• _底線在golang中的使用
  
  • 一種情況是佔位用的，方法返回兩個結果，而你只想要一個結果，那另一個就用 _ 佔位，而如果用變數的話，不使用，編譯器是會報錯的。
  • 還有一種情況時類似於 import _ “fmt” 這種，import 一個包進來，但是不使用，只是讓包自己初始化一下，運行一下包內部的init（）函數，否則匯入包不用也是會報錯的。但也要記住，這種情況下是不用調用包內其他的函數或者變數的。

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