add chapter 15.7 (#683)

eBook/examples/chapter_15/pipeline1.go

@@ -0,0 +1,18 @@
+// pipeline1.go
+package main
+
+import (
+	"os"
+	"text/template"
+)
+
+func main() {
+	t := template.New("template test")
+	t = template.Must(t.Parse("This is just static text. \n{{\"This is pipeline data - because it is evaluated within the double braces.\"}} {{`So is this, but within reverse quotes.`}}\n"))
+	t.Execute(os.Stdout, nil)
+}
+
+/*
+This is just static text.
+This is pipeline data - because it is evaluated within the double braces. So is this, but within reverse quotes.
+*/

eBook/examples/chapter_15/predefined_functions.go

@@ -0,0 +1,15 @@
+// predefined_functions.go
+package main
+
+import (
+	"os"
+	"text/template"
+)
+
+func main() {
+	t := template.New("test")
+	t = template.Must(t.Parse("{{with $x := `hello`}}{{printf `%s %s` $x `Mary`}}{{end}}!\n"))
+	t.Execute(os.Stdout, nil)
+}
+
+// hello Mary!

eBook/examples/chapter_15/template_field.go

@@ -0,0 +1,24 @@
+// template_field.go
+package main
+
+import (
+	"fmt"
+	"os"
+	"text/template"
+)
+
+type Person struct {
+	Name string
+	nonExportedAgeField string
+}
+
+func main() {
+	t := template.New("hello")
+	t, _ = t.Parse("hello {{.Name}}!")
+	p := Person{Name: "Mary", nonExportedAgeField: "31"}
+	if err := t.Execute(os.Stdout, p); err != nil {
+		fmt.Println("There was an error:", err.Error())
+	}
+}
+
+// Output:   hello Mary!

eBook/examples/chapter_15/template_ifelse.go

@@ -0,0 +1,27 @@
+// template_ifelse.go
+package main
+
+import (
+	"os"
+	"text/template"
+)
+
+func main() {
+	tEmpty := template.New("template test")
+	tEmpty = template.Must(tEmpty.Parse("Empty pipeline if demo: {{if ``}} Will not print. {{end}}\n")) //empty pipeline following if
+	tEmpty.Execute(os.Stdout, nil)
+
+	tWithValue := template.New("template test")
+	tWithValue = template.Must(tWithValue.Parse("Non empty pipeline if demo: {{if `anything`}} Will print. {{end}}\n")) //non empty pipeline following if condition
+	tWithValue.Execute(os.Stdout, nil)
+
+	tIfElse := template.New("template test")
+	tIfElse = template.Must(tIfElse.Parse("if-else demo: {{if `anything`}} Print IF part. {{else}} Print ELSE part.{{end}}\n")) //non empty pipeline following if condition
+	tIfElse.Execute(os.Stdout, nil)
+}
+
+/* Output:
+Empty pipeline if demo:
+Non empty pipeline if demo:  Will print.
+if-else demo:  Print IF part.
+*/

eBook/examples/chapter_15/template_validation.go

@@ -0,0 +1,23 @@
+// template_validation.go
+package main
+
+import (
+	"text/template"
+	"fmt"
+)
+
+func main() {
+	tOk := template.New("ok")
+	//a valid template, so no panic with Must:
+	template.Must(tOk.Parse("/* and a comment */ some static text: {{ .Name }}"))
+	fmt.Println("The first one parsed OK.")
+	fmt.Println("The next one ought to fail.")
+	tErr := template.New("error_template")
+	template.Must(tErr.Parse(" some static text {{ .Name }"))
+}
+
+/* Output:
+The first one parsed OK.
+The next one ought to fail.
+panic: template: error_template:1: unexpected "}" in command
+*/

eBook/examples/chapter_15/template_variables.go

@@ -0,0 +1,25 @@
+// template_variables.go
+package main
+
+import (
+	"os"
+	"text/template"
+)
+
+func main() {
+	t := template.New("test")
+	t = template.Must(t.Parse("{{with $3 := `hello`}}{{$3}}{{end}}!\n"))
+	t.Execute(os.Stdout, nil)
+
+	t = template.Must(t.Parse("{{with $x3 := `hola`}}{{$x3}}{{end}}!\n"))
+	t.Execute(os.Stdout, nil)
+
+	t = template.Must(t.Parse("{{with $x_1 := `hey`}}{{$x_1}} {{.}} {{$x_1}}{{end}}!\n"))
+	t.Execute(os.Stdout, nil)
+}
+
+/* Output:
+hello!
+hola!
+hey hey hey!
+*/

eBook/examples/chapter_15/template_with_end.go

@@ -0,0 +1,21 @@
+// template_with_end.go
+package main
+
+import (
+	"os"
+	"text/template"
+)
+
+func main() {
+	t := template.New("test")
+	t, _ = t.Parse("{{with `hello`}}{{.}}{{end}}!\n")
+	t.Execute(os.Stdout, nil)
+
+	t, _ = t.Parse("{{with `hello`}}{{.}} {{with `Mary`}}{{.}}{{end}}{{end}}!\n")
+	t.Execute(os.Stdout, nil)
+}
+
+/* Output:
+hello!
+hello Mary!
+*/