Migrate all backends & readme to use constructorish New...

README.md

@@ -61,11 +61,11 @@ import "github.com/spf13/afero"
 
 First define a package variable and set it to a pointer to a filesystem.
 ```go
-var AppFs afero.Fs = &afero.MemMapFs{}
+var AppFs afero.Fs = afero.NewMemMapFs()
 
 or
 
-var AppFs afero.Fs = &afero.OsFs{}
+var AppFs afero.Fs = afero.NewOsFs()
 ```
 It is important to note that if you repeat the composite literal you
 will be using a completely new and isolated filesystem. In the case of
@@ -166,7 +166,7 @@ f, err := afero.TempFile(fs,"", "ioutil-test")
 ### Calling via Afero
 
 ```go
-fs := new(afero.MemMapFs)
+fs := afero.NewMemMapFs
 afs := &Afero{Fs: fs}
 f, err := afs.TempFile("", "ioutil-test")
 ```
@@ -187,39 +187,28 @@ backend is perfect for testing.
 * No test cleanup needed
 
 One way to accomplish this is to define a variable as mentioned above.
-In your application this will be set to &afero.OsFs{} during testing you
-can set it to &afero.MemMapFs{}.
+In your application this will be set to afero.NewOsFs() during testing you
+can set it to afero.NewMemMapFs().
 
 It wouldn't be uncommon to have each test initialize a blank slate memory
-backend. To do this I would define my `appFS = &afero.OsFs{}` somewhere
+backend. To do this I would define my `appFS = afero.NewOsFs()` somewhere
 appropriate in my application code. This approach ensures that Tests are order
 independent, with no test relying on the state left by an earlier test.
 
 Then in my tests I would initialize a new MemMapFs for each test:
 ```go
 func TestExist(t *testing.T) {
-	appFS = &afero.MemMapFs{}
+	appFS = afero.NewMemMapFs()
 	// create test files and directories
 	appFS.MkdirAll("src/a", 0755))
 	appFS.WriteFile("src/a/b", []byte("file b"), 0644)
 	appFS.WriteFile("src/c", []byte("file c"), 0644)
-	testExistence("src/c", true, t)
-}
-
-func testExistence(name string, e bool, t *testing.T) {
-	_, err := appFS.Stat(name)
+	_, err := appFS.Stat("src/c")
 	if os.IsNotExist(err) {
-	    if e {
         t.Errorf("file \"%s\" does not exist.\n", name)
 	}
-	} else if err != nil {
-    	panic(err)
-	} else {
-    	if !e {
-    	    t.Errorf("file \"%s\" exists.\n", name)
-    	}
-	}
 }
+
 ```
 
 # Available Backends
@@ -233,6 +222,11 @@ very easy to use as all of the calls are the same as the existing OS
 calls. It also makes it trivial to have your code use the OS during
 operation and a mock filesystem during testing or as needed.
 
+```go
+appfs := NewOsFs()
+appfs.MkdirAll("src/a", 0755))
+```
+
 ## Memory Backed Storage
 
 ### MemMapFs
@@ -242,6 +236,11 @@ mocking and to speed up unnecessary disk io when persistence isn’t
 necessary. It is fully concurrent and will work within go routines
 safely.
 
+```go
+mm := NewMemMapFs()
+mm.MkdirAll("src/a", 0755))
+```
+
 #### InMemoryFile
 
 As part of MemMapFs, Afero also provides an atomic, fully concurrent memory
@@ -265,7 +264,7 @@ The given file name to the operations on this Fs will be prepended with
 the base path before calling the source Fs.
 
 ```go
-bp := &BasePathFs{source: &OsFs{}, path: "/base/path"}
+bp := NewBasePathFs(NewOsFs(), "/base/path")
 ```
 
 ### ReadOnlyFs
@@ -273,7 +272,7 @@ bp := &BasePathFs{source: &OsFs{}, path: "/base/path"}
 A thin wrapper around the source Fs providing a read only view.
 
 ```go
-fs := &ReadOnlyFs{source: &OsFs{}}
+fs := NewReadOnlyFs(NewOsFs())
 _, err := fs.Create("/file.txt")
 // err = syscall.EPERM
 ```
@@ -286,7 +285,7 @@ Files not matching the regexp provided will not be created.
 Directories are not filtered.
 
 ```go
-fs := &RegexpFs{re: regexp.MustCompile(`\.txt$`), source: &MemMapFs{}}
+fs := NewRegexpFs(NewMemMapFs(), regexp.MustCompile(`\.txt$`))
 _, err := fs.Create("/file.html")
 // err = syscall.ENOENT
 ```
@@ -303,7 +302,7 @@ Afero provides an httpFs file system which satisfies this requirement.
 Any Afero FileSystem can be used as an httpFs.
 
 ```go
-httpFs := &afero.HttpFs{source: <ExistingFS>}
+httpFs := afero.NewHttpFs(<ExistingFS>)
 fileserver := http.FileServer(httpFs.Dir(<PATH>)))
 http.Handle("/", fileserver)
 ```
@@ -335,9 +334,9 @@ from the base to the overlay when they're not present (or outdated) in the
 caching layer.
 
 ```go
-base := &OsFs{}
-layer := &MemMapFs{}
-ufs := &CacheOnReadFs{base: base, layer: layer, cacheTime: 100 * time.Second}
+base := NewOsFs()
+layer := NewMemMapFs()
+ufs := NewCacheOnReadFs(base, layer, 100 * time.Second)
 ```
 
 ### CopyOnWriteFs()
@@ -361,17 +360,17 @@ overlay will be removed/renamed.
 The writable overlay layer is currently limited to MemMapFs.
 
 ```go
-	base := &OsFs{}
-	roBase := &ReadOnlyFs{source: base}
-	ufs := &CopyOnWriteFs{base: roBase, layer: &MemMapFs{}}
+	base := NewOsFs()
+	roBase := NewReadOnlyFs(base)
+	ufs := NewCopyOnWriteFs(roBase, NewMemMapFs())
 
 	fh, _ = ufs.Create("/home/test/file2.txt")
 	fh.WriteString("This is a test")
 	fh.Close()
 ```
 
-In this example all write operations will only occur in memory (&MemMapFs{})
-leaving the base filesystem (&OsFs) untouched.
+In this example all write operations will only occur in memory (MemMapFs)
+leaving the base filesystem (OsFs) untouched.
 
 
 ## Desired/possible backends

basepath.go

@@ -20,6 +20,10 @@ type BasePathFs struct {
 	path   string
 }
 
+func NewBasePathFs(source Fs, path string) Fs {
+	return &BasePathFs{source: source, path: path}
+}
+
 // on a file outside the base path it returns the given file name and an error,
 // else the given file with the base path prepended
 func (b *BasePathFs) RealPath(name string) (path string, err error) {

basepath_test.go

@@ -7,7 +7,7 @@ import (
 func TestBasePath(t *testing.T) {
 	baseFs := &MemMapFs{}
 	baseFs.MkdirAll("/base/path/tmp", 0777)
-	bp := &BasePathFs{source: baseFs, path: "/base/path"}
+	bp := NewBasePathFs(baseFs, "/base/path")
 
 	if _, err := bp.Create("/tmp/foo"); err != nil {
 		t.Errorf("Failed to set real path")

httpFs.go

@@ -20,6 +20,7 @@ import (
 	"path"
 	"path/filepath"
 	"strings"
+	"time"
 )
 
 type httpDir struct {
@@ -48,6 +49,10 @@ type HttpFs struct {
 	source Fs
 }
 
+func NewHttpFs(source Fs) *HttpFs {
+	return &HttpFs{source: source}
+}
+
 func (h HttpFs) Dir(s string) *httpDir {
 	return &httpDir{basePath: s, fs: h}
 }
@@ -58,6 +63,14 @@ func (h HttpFs) Create(name string) (File, error) {
 	return h.source.Create(name)
 }
 
+func (h HttpFs) Chmod(name string, mode os.FileMode) error {
+	return h.source.Chmod(name, mode)
+}
+
+func (h HttpFs) Chtimes(name string, atime time.Time, mtime time.Time) error {
+	return h.source.Chtimes(name, atime, mtime)
+}
+
 func (h HttpFs) Mkdir(name string, perm os.FileMode) error {
 	return h.source.Mkdir(name, perm)
 }

memmap.go

@@ -31,6 +31,10 @@ type MemMapFs struct {
 	init sync.Once
 }
 
+func NewMemMapFs() Fs {
+	return &MemMapFs{}
+}
+
 var memfsInit sync.Once
 
 func (m *MemMapFs) getData() map[string]*mem.FileData {

memmap_test.go

@@ -34,7 +34,7 @@ func TestNormalizePath(t *testing.T) {
 func TestPathErrors(t *testing.T) {
 	path := filepath.Join(".", "some", "path")
 	path2 := filepath.Join(".", "different", "path")
-	fs := &MemMapFs{}
+	fs := NewMemMapFs()
 	perm := os.FileMode(0755)
 
 	// relevant functions:

os.go

@@ -25,6 +25,10 @@ import (
 // (http://golang.org/pkg/os/).
 type OsFs struct{}
 
+func NewOsFs() Fs {
+	return &OsFs{}
+}
+
 func (OsFs) Name() string { return "OsFs" }
 
 func (OsFs) Create(name string) (File, error) {

readonlyfs.go

@@ -10,6 +10,10 @@ type ReadOnlyFs struct {
 	source Fs
 }
 
+func NewReadOnlyFs(source Fs) Fs {
+	return &ReadOnlyFs{source: source}
+}
+
 func (r *ReadOnlyFs) ReadDir(name string) ([]os.FileInfo, error) {
 	return ReadDir(r.source, name)
 }

regexpfs.go

@@ -16,6 +16,10 @@ type RegexpFs struct {
 	source Fs
 }
 
+func NewRegexpFs(source Fs, re *regexp.Regexp) Fs {
+	return &RegexpFs{source: source, re: re}
+}
+
 type RegexpFile struct {
 	f  File
 	re *regexp.Regexp

ro_regexp_test.go

@@ -20,7 +20,7 @@ func TestFilterReadonlyRemoveAndRead(t *testing.T) {
 	fh.Write([]byte("content here"))
 	fh.Close()
 
-	fs := &ReadOnlyFs{source: mfs}
+	fs := NewReadOnlyFs(mfs)
 	err = fs.Remove("/file.txt")
 	if err == nil {
 		t.Errorf("Did not fail to remove file")
@@ -51,7 +51,7 @@ func TestFilterReadonlyRemoveAndRead(t *testing.T) {
 }
 
 func TestFilterRegexp(t *testing.T) {
-	fs := &RegexpFs{re: regexp.MustCompile(`\.txt$`), source: &MemMapFs{}}
+	fs := NewRegexpFs(&MemMapFs{}, regexp.MustCompile(`\.txt$`))
 	_, err := fs.Create("/file.html")
 	if err == nil {
 

union.go

@@ -21,8 +21,8 @@ import (
 // successful read in the overlay will move the cursor position in the base layer
 // by the number of bytes read.
 type UnionFile struct {
-	layer File
 	base  File
+	layer File
 	off   int
 	files []os.FileInfo
 }

union_cache.go

@@ -25,6 +25,10 @@ type CacheOnReadFs struct {
 	cacheTime time.Duration
 }
 
+func NewCacheOnReadFs(base Fs, layer Fs, cacheTime time.Duration) Fs {
+	return &CacheOnReadFs{base: base, layer: layer, cacheTime: cacheTime}
+}
+
 type cacheState int
 
 const (

union_cow.go

@@ -22,6 +22,10 @@ type CopyOnWriteFs struct {
 	layer Fs
 }
 
+func NewCopyOnWriteFs(base Fs, layer Fs) Fs {
+	return &CopyOnWriteFs{base: base, layer: layer}
+}
+
 func (u *CopyOnWriteFs) isBaseFile(name string) (bool, error) {
 	if _, err := u.layer.Stat(name); err == nil {
 		return false, nil

union_test.go

@@ -11,7 +11,7 @@ func TestUnionCreateExisting(t *testing.T) {
 	base := &MemMapFs{}
 	roBase := &ReadOnlyFs{source: base}
 
-	ufs := &CopyOnWriteFs{base: roBase, layer: &MemMapFs{}}
+	ufs := NewCopyOnWriteFs(roBase, &MemMapFs{})
 
 	base.MkdirAll("/home/test", 0777)
 	fh, _ := base.Create("/home/test/file.txt")
@@ -86,7 +86,7 @@ func TestUnionCacheWrite(t *testing.T) {
 	base := &MemMapFs{}
 	layer := &MemMapFs{}
 
-	ufs := &CacheOnReadFs{base: base, layer: layer, cacheTime: 0}
+	ufs := NewCacheOnReadFs(base, layer, 0)
 
 	base.Mkdir("/data", 0777)