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--- wiki2:go_useful [2019/08/20 10:45]
alfred [Program]
+++ wiki2:go_useful [2020/05/09 09:25] (actual)
@@ Línea 19: / Línea 19: @@
-==== dep tool for managing dependences ====
+==== go mod for managing dependences ====
+After Go 1.11.
+<code>
+go mod init <project name>
+# Do not do it in the GOPATH
+</code>
+When you do ''go build'' it downloads dependencies automatically.
+There will appear ''go.mod'' y ''go.sum'' files. The first one to list dependences, the second one the checksums.
+<code>
+go mod tidy      # To remove non-used libraries
+go mod vendor    # To vendor dependencies in vendor directory.
+</code>
+Then, if you added a new package to your project, to use them:
+<code>
+import "project/package"
+</code>
+==== dep tool for managing dependences (DEPRECATED) ====
 To install: ''apt install go-dep''. To initialize a project:
@@ Línea 101: / Línea 121: @@
 ====== Gotchas ======
+===== Basic =====
+<code>
+// Define a string array variable
+var (
+   viewNames       = []string{"projects", "generations", "info", "menu"}
+)
+// Loop over an slice
+for _, v := range viewNames {
+  fmt.Println(v)
+}
+// Get a variable without using it
+_, err := g.SetCurrentView(name)
+</code>
+===== Conversions =====
+Previous code:
+<code>
+import "strconv"
+</code>
+Code
+<code>
+// String to byte[]
+buff := []byte("Here is a string....")
+// Byte to String
+str := string(buff)
+// Int to string
+str := strconv.Itoa(currentNumber)
+</code>
 ===== Program =====
 Previous code used:
@@ Línea 109: / Línea 161: @@
 <code>
 argumentsWithoutProgramName = os.Args[1:]
+settings_path = os.Getenv("GLOUDVIEWER_CONFIG")
 </code>
+===== Arrays (or, in Go: Slices) =====
+<code>
+len(arr)
+</code>
+===== Maps =====
+<code>
+var m map[string]Vertex
+m = make(map[string]Vertex)
+m["Bell Labs"] = Vertex{40.68433, -74.39967}
+</code>
+<code>
+keys := make([]keyType, 0, len(myMap))
+values := make([]valueType, 0, len(myMap))
+for k, v := range myMap {
+	keys = append(keys, k)
+	values = append(values, v)
+}
+</code>
 ===== Go Routines =====
 Previous code used:
@@ Línea 130: / Línea 205: @@
 }("going")
 </code>
-===== Arrays (or, in Go: Slices) =====
+===== Not so common types =====
+Previous code:
 <code>
-len(arr)
+import "bytes"
+</code>
+Code:
+<code>
+// String buffer
+buf := bytes.NewBufferString("")
+fmt.Fprintln(buf, "Hello!")
+str := buf.String()
+</code>
+===== JSON =====
+Previous code used:
+<code>
+import "io/ioutil"
+import "encoding/json"
+type Generation struct {
+	Project         string
+	Author          string `json:"author"`
+	Version         string `json:"version"`
+}
+</code>
+Code:
+<code>
+// JSON file to struct object
+b, err := ioutil.ReadFile(path)
+if err != nil {
+   panic(err)
+}
+generation := Generation{}
+json.Unmarshal(b, &generation)
+</code>
+===== Filesystem =====
+Previous code:
+<code>
+import "strings"
+import "path"
+import "path/filepath"
+</code>
+Code:
+<code>
+// info is info os.FileInfo type
+// Is a directory:
+info.IsDir()
+// Get parent path from a path (pth)
+filepath.Dir(pth)
+// File name without extension:
+strings.TrimSuffix(info.Name(), pth.Ext(info.Name())
+// Join path
+path.Join(arguments[0], selectedProject)
+</code>
+====== Snippets ======
+===== Map, reduce, filter in Go =====
+<code>
+func mapXtoY(collection []X, fn func(elem X) Y) []Y {
+	var result []Y
+	for _, item := range collection {
+		result = append(result, fn(item))
+	}
+	return result
+}
+func reduceXtoY(collection []X, init Y, fn func(memo Y, elem X) Y) Y {
+	result := init
+	for _, item := range collection {
+		result = fn(result, item)
+	}
+	return result
+}
+func filterXs(collection []X, fn func(elem X) bool) []X {
+	var result []X
+	for _, item := range collection {
+		if fn(item) {
+			result = append(result, item)
+		}
+	}
+	return result
+}
+</code>
+===== Nested functions =====
+<code>
+func f() {
+    foo := func(s string) {
+        fmt.Println(s)
+    }
+    foo("Hello World!")
+}
 </code>

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