Merge pull request #24652 from lujun9972/add-MjAxNzAxMTUgTWFnaWMgR09QQVRILm1kCg==

自动选题[tech]: 20170115 Magic GOPATH

sources/tech/20170115 Magic GOPATH.md

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+[#]: collector: (lujun9972)
+[#]: translator: ( )
+[#]: reviewer: ( )
+[#]: publisher: ( )
+[#]: url: ( )
+[#]: subject: (Magic GOPATH)
+[#]: via: (https://www.jtolio.com/2017/01/magic-gopath)
+[#]: author: (jtolio.com https://www.jtolio.com/)
+
+Magic GOPATH
+======
+
+_**Update:** With the advent of Go 1.11 and [Go modules][1], this whole post is now useless. Unset your GOPATH entirely and switch to Go modules today!_
+
+Maybe someday I’ll start writing about things besides Go again.
+
+Go requires that you set an environment variable for your workspace called your `GOPATH`. The `GOPATH` is one of the most confusing aspects of Go to newcomers and even relatively seasoned developers alike. It’s not immediately clear what would be better, but finding a good `GOPATH` value has implications for your source code repository layout, how many separate projects you have on your computer, how default project installation instructions work (via `go get`), and even how you interoperate with other projects and libraries.
+
+It’s taken until Go 1.8 to decide to [set a default][2] and that small change was one of [the most talked about code reviews][3] for the 1.8 release cycle.
+
+After [writing about GOPATH himself][4], [Dave Cheney][5] [asked me][6] to write a blog post about what I do.
+
+### My proposal
+
+I set my `GOPATH` to always be the current working directory, unless a parent directory is clearly the `GOPATH`.
+
+Here’s the relevant part of my `.bashrc`:
+
+```
+# bash command to output calculated GOPATH.
+calc_gopath() {
+  local dir="$PWD"
+
+  # we're going to walk up from the current directory to the root
+  while true; do
+
+    # if there's a '.gopath' file, use its contents as the GOPATH relative to
+    # the directory containing it.
+    if [ -f "$dir/.gopath" ]; then
+      ( cd "$dir";
+        # allow us to squash this behavior for cases we want to use vgo
+        if [ "$(cat .gopath)" != "" ]; then
+          cd "$(cat .gopath)";
+          echo "$PWD";
+        fi; )
+      return
+    fi
+
+    # if there's a 'src' directory, the parent of that directory is now the
+    # GOPATH
+    if [ -d "$dir/src" ]; then
+      echo "$dir"
+      return
+    fi
+
+    # we can't go further, so bail. we'll make the original PWD the GOPATH.
+    if [ "$dir" == "/" ]; then
+      echo "$PWD"
+      return
+    fi
+
+    # now we'll consider the parent directory
+    dir="$(dirname "$dir")"
+  done
+}
+
+my_prompt_command() {
+  export GOPATH="$(calc_gopath)"
+
+  # you can have other neat things in here. I also set my PS1 based on git
+  # state
+}
+
+case "$TERM" in
+xterm*|rxvt*)
+  # Bash provides an environment variable called PROMPT_COMMAND. The contents
+  # of this variable are executed as a regular Bash command just before Bash
+  # displays a prompt. Let's only set it if we're in some kind of graphical
+  # terminal I guess.
+  PROMPT_COMMAND=my_prompt_command
+  ;;
+*)
+  ;;
+esac
+```
+
+The benefits are fantastic. If you want to quickly `go get` something and not have it clutter up your workspace, you can do something like:
+
+```
+cd $(mktemp -d) && go get github.com/the/thing
+```
+
+On the other hand, if you’re jumping between multiple projects (whether or not they have the full workspace checked in or are just library packages), the `GOPATH` is set accurately.
+
+More flexibly, if you have a tree where some parent directory is outside of the `GOPATH` but you want to set the `GOPATH` anyways, you can create a `.gopath` file and it will automatically set your `GOPATH` correctly any time your shell is inside that directory.
+
+The whole thing is super nice. I kinda can’t imagine doing something else anymore.
+
+### Fin.
+
+--------------------------------------------------------------------------------
+
+via: https://www.jtolio.com/2017/01/magic-gopath
+
+作者：[jtolio.com][a]
+选题：[lujun9972][b]
+译者：[译者ID](https://github.com/译者ID)
+校对：[校对者ID](https://github.com/校对者ID)
+
+本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
+
+[a]: https://www.jtolio.com/
+[b]: https://github.com/lujun9972
+[1]: https://golang.org/cmd/go/#hdr-Modules__module_versions__and_more
+[2]: https://rakyll.org/default-gopath/
+[3]: https://go-review.googlesource.com/32019/
+[4]: https://dave.cheney.net/2016/12/20/thinking-about-gopath
+[5]: https://dave.cheney.net/
+[6]: https://twitter.com/davecheney/status/811334240247812097