Merge branch 'pull-10'

README.md

@@ -268,6 +268,37 @@ printos:
     - echo 'Is SH? {{IsSH}}'
 ```
 
+### Help
+
+Running `task help` lists all tasks with a description. The following taskfile:
+
+```yml
+build:
+  desc: Build the go binary.
+  cmds:
+    - go build -v -i main.go
+
+test:
+  desc: Run all the go tests.
+  cmds:
+    - go test -race ./...
+
+js:
+  cmds:
+    - npm run buildjs
+
+css:
+  cmds:
+    - npm run buildcss
+```
+
+would print the following output:
+
+```bash
+build   Build the go binary.
+test    Run all the go tests.
+```
+
 ## Alternatives
 
 Similar software:

Taskfile.yml

@@ -1,20 +1,24 @@
 # compiles current source code and make "task" executable available on
 # $GOPATH/bin/task{.exe}
 install:
+  desc: Installs Task
   cmds:
     - go install -v ./...
 
 lint:
+  desc: Runs golint
   cmds:
     - golint .
     - golint ./cmd/task
 
 test:
+  desc: Runs test suite
   deps: [install]
   cmds:
     - go test -v
 
 # https://github.com/goreleaser/goreleaser
 release:
+  desc: Release Task
   cmds:
     - goreleaser

help.go

@@ -0,0 +1,33 @@
+package task
+
+import (
+	"fmt"
+	"os"
+	"sort"
+	"text/tabwriter"
+)
+
+func printExistingTasksHelp() {
+	tasks := tasksWithDesc()
+	if len(tasks) == 0 {
+		return
+	}
+	fmt.Println("Available tasks for this project:")
+
+	// Format in tab-separated columns with a tab stop of 8.
+	w := tabwriter.NewWriter(os.Stdout, 0, 8, 0, '\t', 0)
+	for _, task := range tasks {
+		fmt.Fprintln(w, fmt.Sprintf("- %s:\t%s", task, Tasks[task].Desc))
+	}
+	w.Flush()
+}
+
+func tasksWithDesc() (tasks []string) {
+	for name, task := range Tasks {
+		if task.Desc != "" {
+			tasks = append(tasks, name)
+		}
+	}
+	sort.Strings(tasks)
+	return
+}

task.go

@@ -30,6 +30,7 @@ var (
 type Task struct {
 	Cmds      []string
 	Deps      []string
+	Desc      string
 	Sources   []string
 	Generates []string
 	Dir       string
@@ -54,6 +55,16 @@ func Run() {
 		log.Fatal(err)
 	}
 
+	// check if given tasks exist
+	for _, a := range args {
+		if _, ok := Tasks[a]; !ok {
+			var err error = &taskNotFoundError{taskName: a}
+			fmt.Println(err)
+			printExistingTasksHelp()
+			return
+		}
+	}
+
 	for _, a := range args {
 		if err = RunTask(a); err != nil {
 			log.Fatal(err)