ADDED example comment to toml file on init #343

fs.go

@@ -75,6 +75,14 @@ func writeFile(path string, in toml.Marshaler) error {
 	return err
 }
 
+// modifyWithString - Modifies a given file with a new string input.
+// This is used to write arbitrary string data to a file, such as
+// updating the `Gopkg.toml` file with example data if no deps found
+// on init.
+func modifyWithString(path, data string) error {
+	return ioutil.WriteFile(path, []byte(data), 0644)
+}
+
 // renameWithFallback attempts to rename a file or directory, but falls back to
 // copying in the event of a cross-link device error. If the fallback copy
 // succeeds, src is still removed, emulating normal rename behavior.

manifest.go

@@ -9,6 +9,7 @@ import (
 	"sort"
 
 	"bytes"
+
 	"github.com/pelletier/go-toml"
 	"github.com/pkg/errors"
 	"github.com/sdboyer/gps"

txn_writer.go

@@ -19,6 +19,16 @@ import (
 	"github.com/sdboyer/gps"
 )
 
+// Example string to be written to the manifest file
+// if no dependencies are found in the project
+// during `dep init`
+const exampleToml = `
+# Example:
+# [[dependencies]]
+# branch = "master"
+# name = "github.com/vendor/package"
+`
+
 // SafeWriter transactionalizes writes of manifest, lock, and vendor dir, both
 // individually and in any combination, into a pseudo-atomic action with
 // transactional rollback.
@@ -172,6 +182,7 @@ const (
 // - If oldLock is provided without newLock, error.
 // - If vendor is VendorAlways without a newLock, error.
 func (sw *SafeWriter) Prepare(manifest *Manifest, oldLock, newLock *Lock, vendor VendorBehavior) error {
+
 	sw.Payload = &SafeWriterPayload{
 		Manifest: manifest,
 		Lock:     newLock,
@@ -227,6 +238,7 @@ func (payload SafeWriterPayload) validate(root string, sm gps.SourceManager) err
 // This mostly guarantees that dep cannot exit with a partial write that would
 // leave an undefined state on disk.
 func (sw *SafeWriter) Write(root string, sm gps.SourceManager) error {
+
 	if sw.Payload == nil {
 		return errors.New("Cannot call SafeWriter.Write before SafeWriter.Prepare")
 	}
@@ -349,6 +361,13 @@ func (sw *SafeWriter) Write(root string, sm gps.SourceManager) error {
 		os.RemoveAll(vendorbak)
 	}
 
+	if len(sw.Payload.Manifest.Dependencies) == 0 {
+		err := modifyWithString(mpath, exampleToml)
+		if err != nil {
+			goto fail
+		}
+	}
+
 	return nil
 
 fail: