add Stringify function

This provides somewhat reasonable string representations of GitHub
structs.  This is specifically designed for this library and takes a
number of shortcuts where it can, so is not suitable as a general
purpose solution.  That said, I am exporting this function because it is
useful for things like printing out slices of GitHub structs, as can be
seen in examples/example.go.

I am certainly open to suggestions for what exactly the stringified
output should look like.  Currently, I think I've found a reasonable
compromise between fmt's "%v" and "%s" output.

Author: willnorris

examples/example.go

@@ -21,7 +21,7 @@ func main() {
 	if err != nil {
 		fmt.Printf("error: %v\n\n", err)
 	} else {
-		fmt.Printf("%#v\n\n", repos)
+		fmt.Printf("%v\n\n", github.Stringify(repos))
 	}
 
 	rate, _, err := client.RateLimit()

github/activity_events.go

@@ -25,6 +25,10 @@ type Event struct {
 	ID         *string          `json:"id,omitempty"`
 }
 
+func (e *Event) String() string {
+	return Stringify(e)
+}
+
 // Payload returns the parsed event payload. For recognized event types
 // (PushEvent), a value of the corresponding struct type will be returned.
 func (e *Event) Payload() (payload interface{}) {
@@ -49,6 +53,10 @@ type PushEvent struct {
 	Commits []PushEventCommit `json:"commits,omitempty"`
 }
 
+func (p *PushEvent) String() string {
+	return Stringify(p)
+}
+
 // PushEventCommit represents a git commit in a GitHub PushEvent.
 type PushEventCommit struct {
 	SHA      *string       `json:"sha,omitempty"`
@@ -58,6 +66,10 @@ type PushEventCommit struct {
 	Distinct *bool         `json:"distinct"`
 }
 
+func (p *PushEventCommit) String() string {
+	return Stringify(p)
+}
+
 // List public events.
 //
 // GitHub API docs: http://developer.github.com/v3/activity/events/#list-public-events

github/gists.go

@@ -33,6 +33,10 @@ type Gist struct {
 	CreatedAt   *time.Time                `json:"created_at,omitempty"`
 }
 
+func (g *Gist) String() string {
+	return Stringify(g)
+}
+
 // GistFilename represents filename on a gist.
 type GistFilename string
 
@@ -44,6 +48,10 @@ type GistFile struct {
 	Content  *string `json:"content,omitempty"`
 }
 
+func (g *GistFile) String() string {
+	return Stringify(g)
+}
+
 // GistListOptions specifies the optional parameters to the
 // GistsService.List, GistsService.ListAll, and GistsService.ListStarred methods.
 type GistListOptions struct {

github/gists_comments.go

@@ -19,6 +19,10 @@ type GistComment struct {
 	CreatedAt *time.Time `json:"created_at,omitempty"`
 }
 
+func (g *GistComment) String() string {
+	return Stringify(g)
+}
+
 // ListComments lists all comments for a gist.
 //
 // GitHub API docs: http://developer.github.com/v3/gists/comments/#list-comments-on-a-gist

github/git_commits.go

@@ -20,6 +20,10 @@ type Commit struct {
 	Parents   []Commit      `json:"parents,omitempty"`
 }
 
+func (c *Commit) String() string {
+	return Stringify(c)
+}
+
 // CommitAuthor represents the author or committer of a commit.  The commit
 // author may not correspond to a GitHub User.
 type CommitAuthor struct {
@@ -28,6 +32,10 @@ type CommitAuthor struct {
 	Email *string    `json:"email,omitempty"`
 }
 
+func (c *CommitAuthor) String() string {
+	return Stringify(c)
+}
+
 // GetCommit fetchs the Commit object for a given SHA.
 //
 // GitHub API docs: http://developer.github.com/v3/git/commits/#get-a-commit

github/git_trees.go

@@ -13,6 +13,10 @@ type Tree struct {
 	Entries []TreeEntry `json:"tree,omitempty"`
 }
 
+func (t *Tree) String() string {
+	return Stringify(t)
+}
+
 // TreeEntry represents the contents of a tree structure.  TreeEntry can
 // represent either a blob, a commit (in the case of a submodule), or another
 // tree.
@@ -24,6 +28,10 @@ type TreeEntry struct {
 	Size *int    `json:"size,omitempty"`
 }
 
+func (t *TreeEntry) String() string {
+	return Stringify(t)
+}
+
 // GetTree fetches the Tree object for a given sha hash from a repository.
 //
 // GitHub API docs: http://developer.github.com/v3/git/trees/#get-a-tree

github/issues.go

@@ -38,6 +38,10 @@ type Issue struct {
 	// TODO(willnorris): milestone
 }
 
+func (i *Issue) String() string {
+	return Stringify(i)
+}
+
 // IssueListOptions specifies the optional parameters to the IssuesService.List
 // and IssuesService.ListByOrg methods.
 type IssueListOptions struct {

github/issues_comments.go

@@ -20,6 +20,10 @@ type IssueComment struct {
 	UpdatedAt *time.Time `json:"updated_at,omitempty"`
 }
 
+func (i *IssueComment) String() string {
+	return Stringify(i)
+}
+
 // IssueListCommentsOptions specifies the optional parameters to the
 // IssuesService.ListComments method.
 type IssueListCommentsOptions struct {

github/issues_labels.go

@@ -14,8 +14,8 @@ type Label struct {
 	Color *string `json:"color,omitempty"`
 }
 
-func (label Label) String() string {
-	return fmt.Sprint(label.Name)
+func (l Label) String() string {
+	return fmt.Sprint(*l.Name)
 }
 
 // ListLabels lists all labels for a repository.

github/orgs.go

@@ -30,6 +30,10 @@ type Organization struct {
 	CreatedAt *time.Time `json:"created_at,omitempty"`
 }
 
+func (o *Organization) String() string {
+	return Stringify(o)
+}
+
 // List the organizations for a user.  Passing the empty string will list
 // organizations for the authenticated user.
 //

github/orgs_teams.go

@@ -19,6 +19,10 @@ type Team struct {
 	ReposCount   *int    `json:"repos_count,omitempty"`
 }
 
+func (t *Team) String() string {
+	return Stringify(t)
+}
+
 // ListTeams lists all of the teams for an organization.
 //
 // GitHub API docs: http://developer.github.com/v3/orgs/teams/#list-teams

github/pulls.go

@@ -42,6 +42,10 @@ type PullRequest struct {
 	// TODO(willnorris): add head and base once we have a Commit struct defined somewhere
 }
 
+func (p *PullRequest) String() string {
+	return Stringify(p)
+}
+
 // PullRequestListOptions specifies the optional parameters to the
 // PullRequestsService.List method.
 type PullRequestListOptions struct {

github/pulls_comments.go

@@ -23,6 +23,10 @@ type PullRequestComment struct {
 	UpdatedAt *time.Time `json:"updated_at,omitempty"`
 }
 
+func (p *PullRequestComment) String() string {
+	return Stringify(p)
+}
+
 // PullRequestListCommentsOptions specifies the optional parameters to the
 // PullRequestsService.ListComments method.
 type PullRequestListCommentsOptions struct {

github/repos.go

@@ -34,6 +34,10 @@ type Repository struct {
 	HasWiki   *bool `json:"has_wiki"`
 }
 
+func (r *Repository) String() string {
+	return Stringify(r)
+}
+
 // RepositoryListOptions specifies the optional parameters to the
 // RepositoriesService.List method.
 type RepositoryListOptions struct {

github/repos_comments.go

@@ -26,6 +26,10 @@ type RepositoryComment struct {
 	Position *int    `json:"position,omitempty"`
 }
 
+func (r *RepositoryComment) String() string {
+	return Stringify(r)
+}
+
 // ListComments lists all the comments for the repository.
 //
 // GitHub API docs: http://developer.github.com/v3/repos/comments/#list-commit-comments-for-a-repository

github/repos_hooks.go

@@ -33,6 +33,10 @@ type WebHookPayload struct {
 	Repo       *Repository     `json:"repository,omitempty"`
 }
 
+func (w *WebHookPayload) String() string {
+	return Stringify(w)
+}
+
 // WebHookCommit represents the commit variant we receive from GitHub in a
 // WebHookPayload.
 type WebHookCommit struct {
@@ -47,6 +51,10 @@ type WebHookCommit struct {
 	Timestamp *time.Time     `json:"timestamp,omitempty"`
 }
 
+func (w *WebHookCommit) String() string {
+	return Stringify(w)
+}
+
 // WebHookAuthor represents the author or committer of a commit, as specified
 // in a WebHookCommit.  The commit author may not correspond to a GitHub User.
 type WebHookAuthor struct {
@@ -55,6 +63,10 @@ type WebHookAuthor struct {
 	Username *string `json:"username,omitempty"`
 }
 
+func (w *WebHookAuthor) String() string {
+	return Stringify(w)
+}
+
 // Hook represents a GitHub (web and service) hook for a repository.
 type Hook struct {
 	CreatedAt *time.Time             `json:"created_at,omitempty"`
@@ -66,6 +78,10 @@ type Hook struct {
 	ID        *int                   `json:"id,omitempty"`
 }
 
+func (h *Hook) String() string {
+	return Stringify(h)
+}
+
 // CreateHook creates a Hook for the specified repository.
 // Name and Config are required fields.
 //

github/repos_statuses.go

@@ -30,6 +30,10 @@ type RepoStatus struct {
 	UpdatedAt *time.Time `json:"updated_at,omitempty"`
 }
 
+func (r *RepoStatus) String() string {
+	return Stringify(r)
+}
+
 // ListStatuses lists the statuses of a repository at the specified
 // reference.  ref can be a SHA, a branch name, or a tag name.
 //

github/search.go

@@ -102,6 +102,10 @@ type CodeResult struct {
 	Repository *Repository `json:"repository,omitempty"`
 }
 
+func (c *CodeResult) String() string {
+	return Stringify(c)
+}
+
 // Code searches code via various criteria.
 //
 // GitHub API docs: http://developer.github.com/v3/search/#search-code

github/strings.go

@@ -0,0 +1,93 @@
+// Copyright 2013 The go-github AUTHORS. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package github
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+
+	"reflect"
+)
+
+var timestampType = reflect.TypeOf(Timestamp{})
+
+// Stringify attempts to create a reasonable string representation of types in
+// the GitHub library.  It does things like resolve pointers to their values
+// and omits struct fields with nil values.
+func Stringify(message interface{}) string {
+	var buf bytes.Buffer
+	v := reflect.ValueOf(message)
+	stringifyValue(&buf, v)
+	return buf.String()
+}
+
+// stringifyValue was heavily inspired by the goprotobuf library.
+
+func stringifyValue(w io.Writer, val reflect.Value) {
+	if val.Kind() == reflect.Ptr && val.IsNil() {
+		w.Write([]byte("<nil>"))
+		return
+	}
+
+	v := reflect.Indirect(val)
+
+	switch v.Kind() {
+	case reflect.String:
+		fmt.Fprintf(w, `"%s"`, v)
+	case reflect.Slice:
+		w.Write([]byte{'['})
+		for i := 0; i < v.Len(); i++ {
+			if i > 0 {
+				w.Write([]byte{' '})
+			}
+
+			stringifyValue(w, v.Index(i))
+		}
+
+		w.Write([]byte{']'})
+		return
+	case reflect.Struct:
+		if v.Type().Name() != "" {
+			w.Write([]byte(v.Type().String()))
+		}
+
+		// special handling of Timestamp values
+		if v.Type() == timestampType {
+			fmt.Fprint(w, v.Interface())
+			return
+		}
+
+		w.Write([]byte{'{'})
+
+		var sep bool
+		for i := 0; i < v.NumField(); i++ {
+			fv := v.Field(i)
+			if fv.Kind() == reflect.Ptr && fv.IsNil() {
+				continue
+			}
+			if fv.Kind() == reflect.Slice && fv.IsNil() {
+				continue
+			}
+
+			if sep {
+				w.Write([]byte(", "))
+			} else {
+				sep = true
+			}
+
+			w.Write([]byte(v.Type().Field(i).Name))
+			w.Write([]byte{':'})
+			stringifyValue(w, fv)
+		}
+
+		w.Write([]byte{'}'})
+	default:
+		if v.CanInterface() {
+			fmt.Fprint(w, v.Interface())
+		}
+	}
+}