From 6ba27a496a089d0971c137a1a0632a9a10a3be22 Mon Sep 17 00:00:00 2001 From: Russ Cox Date: Fri, 12 Feb 2021 14:32:52 -0500 Subject: _content: move content/static/* to _content/* The extra level of hierarchy here is unnecessary and confusing. The directory is now _content so that any Go source files in our docs are not considered by commands like "go mod tidy" and "go test all". Change-Id: Ib6d7cb12920193798ee825155a8f8b33f16e60d8 Reviewed-on: https://go-review.googlesource.com/c/website/+/291691 Trust: Russ Cox Run-TryBot: Russ Cox TryBot-Result: Go Bot Reviewed-by: Dmitri Shuralyov --- _content/doc/tutorial/call-module-code.html | 237 ++++++++++++++++++++++++++++ 1 file changed, 237 insertions(+) create mode 100644 _content/doc/tutorial/call-module-code.html (limited to '_content/doc/tutorial/call-module-code.html') diff --git a/_content/doc/tutorial/call-module-code.html b/_content/doc/tutorial/call-module-code.html new file mode 100644 index 00000000..b7f7649f --- /dev/null +++ b/_content/doc/tutorial/call-module-code.html @@ -0,0 +1,237 @@ + + +

+ In the previous section, you created a + greetings module. In this section, you'll write code to make + calls to the Hello function in the module you just wrote. You'll + write code you can execute as an application, and which calls code in the + greetings module. +

+ + + +
    +
  1. + Create a hello directory for your Go module source code. This + is where you'll write your caller. + +

    + For example, if your current directory in the command prompt is the + greetings directory, you could use the following commands: +

    + + 
    +cd ..
+mkdir hello
+cd hello
+
    +
    2. + +
  2. + In your text editor (in the hello directory), create a file in which to + write your code and call it hello.go. +
    3. + +
  3. + Write code to call the Hello function, then print the + function's return value. + +

    + To do that, paste the following code into hello.go. +

    + + 
    +package main
+
+import (
+    "fmt"
+
+    "example.com/greetings"
+)
+
+func main() {
+    // Get a greeting message and print it.
+    message := greetings.Hello("Gladys")
+    fmt.Println(message)
+}
+
    + +

    + In this code, you: +

    + +
      +
    • + Declare a main package. In Go, code executed as an + application must go in a main package. +
      • +
    • + Import two packages: example.com/greetings and + fmt. This gives your code access to functions in those + packages. Importing example.com/greetings (the package + contained in the module you created earlier) gives you access to the + Hello function. You also import fmt, with + functions for handling input and output text (such as printing text to + the console). +
      • +
    • + Get a greeting by calling the greetings package’s + Hello function. +
      • +
    +
    4. + +
  4. + Create a new module for this hello package. + +

    + From the command line at the hello directory, run the + go mod init command, giving it the name of the module your + code will be in (here, just use "hello"). +

    + + 
    +$ go mod init hello
+go: creating new go.mod: module hello
+
    +
    5. + +
  5. + Edit the hello module to use the unpublished greetings module. + +

    + For production use, you’d publish your modules on a server, either inside + your company or on the internet, and the Go command will download them + from there. For now, you need to adapt the caller's module so it can find + the greetings code on your local file system. +

    + +

    + To do that, make a small change to hello module’s go.mod + file. +

    + +
      +
    1. + In the hello directory, open the go.mod file, change it so that it looks + like the following, and save the file. + + 
      +module hello
+
+go 1.14
+
+replace example.com/greetings => ../greetings
+
      + +

      + Here, the + replace directive + tells Go to replace the module path (the URL + example.com/greetings) with a path you specify. In this + case, that's a greetings directory next to the hello directory. +

      +
      2. + +
    2. + In the hello directory, run go build to make Go locate the + module and add it as a dependency to the go.mod file. + + 
      +$ go build
+go: found example.com/greetings in example.com/greetings v0.0.0-00010101000000-000000000000
+
      +
      3. + +
    3. + Look at go.mod again to see the changes made by go build, + including the require directive Go added. + + 
      +module hello
+
+go 1.14
+
+replace example.com/greetings => ../greetings
+
+require example.com/greetings v0.0.0-00010101000000-000000000000
+
      + +

      + To build the module, Go found the local code in the ../greetings + directory, then added a + require directive + to specify that hello is dependent on (requires) + example.com/greetings. You created this dependency when + you imported the greetings package (contained in the + greetings module) in hello.go. The replace directive + tells Go where to find the greetings module, because it + isn't published yet. +

      + +

      + To reference a published module, a go.mod file would omit the + replace directive and use a + require directive with a tagged version number at the + end. +

      + + 
      require example.com/greetings v1.1.0
      +
      4. +
    +
    6. + +
  6. + In the hello directory, run the hello executable + (created by go build) to confirm that the code works. +
      +
    • + On Linux or Mac: + + 
      +$ ./hello
+Hi, Gladys. Welcome!
+
      +
      • + +
    • + On Windows: + + 
      +$ hello.exe
+Hi, Gladys. Welcome!
+
      +
      • +
    +
    7. +
+ +

+ Congrats! You've written two functioning modules. In the tutorial's + next topic, you'll add some error handling. +

+ +

+ < Create a Go module + Return and handle an error > +

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