Minor fixup for path:temp-{dir file}.

* Remove `MatchesRegexp` from eval/vals since it is not part of the
  Elvish value protocol.

* Simplify implementation of value matching in `eval/evaltest`.

* Documentation wording tweaks.

0.16.0-release-notes.md

@@ -49,8 +49,8 @@ New features in the standard library:
 
 -   A new `file:` module contains utilities for manipulating files.
 
--   Commands for creating, what are usually meant to be temporary, unique
-    directories, path:temp-dir, and regular files, path:temp-file
+-   Commands for creating temporary files and directories, `path:temp-file`
+    and `path:temp-dir`
     ([#1255](https://b.elv.sh/1255)).
 
 New features in the interactive editor:

pkg/eval/evaltest/evaltest.go

@@ -43,10 +43,6 @@ type Result struct {
 	Exception        error
 }
 
-// MatchingRegexp is used in a `Puts()` call when the value being matched should be a string
-// matching a regexp rather than a literal string.
-type MatchingRegexp struct{ Pattern string }
-
 // The following functions and methods are used to build Test structs. They are
 // supposed to read like English, so a test that "put x" should put "x" reads:
 //
@@ -212,45 +208,37 @@ func capturePort() (*eval.Port, func() ([]interface{}, []byte)) {
 }
 
 func matchOut(want, got []interface{}) bool {
-	if len(got) == 0 && len(want) == 0 {
-		return true
-	}
 	if len(got) != len(want) {
 		return false
 	}
 	for i := range got {
-		switch g := got[i].(type) {
-		case float64:
-			// Special-case float64 to correctly handle NaN and support
-			// approximate comparison.
-			switch w := want[i].(type) {
-			case float64:
-				if !matchFloat64(g, w, 0) {
-					return false
-				}
-			case Approximately:
-				if !matchFloat64(g, w.F, ApproximatelyThreshold) {
-					return false
-				}
-			default:
-				return false
-			}
-		default:
-			switch w := want[i].(type) {
-			case MatchingRegexp:
-				if !vals.MatchesRegexp(got[i], w.Pattern) {
-					return false
-				}
-			default:
-				if !vals.Equal(got[i], want[i]) {
-					return false
-				}
-			}
+		if !match(got[i], want[i]) {
+			return false
 		}
 	}
 	return true
 }
 
+func match(got, want interface{}) bool {
+	switch got := got.(type) {
+	case float64:
+		// Special-case float64 to correctly handle NaN and support
+		// approximate comparison.
+		switch want := want.(type) {
+		case float64:
+			return matchFloat64(got, want, 0)
+		case Approximately:
+			return matchFloat64(got, want.F, ApproximatelyThreshold)
+		}
+	case string:
+		switch want := want.(type) {
+		case MatchingRegexp:
+			return matchRegexp(want.Pattern, got)
+		}
+	}
+	return vals.Equal(got, want)
+}
+
 func reprs(values []interface{}) []string {
 	s := make([]string, len(values))
 	for i, v := range values {

pkg/eval/evaltest/matchers.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"math"
 	"reflect"
+	"regexp"
 
 	"src.elv.sh/pkg/eval"
 )
@@ -27,6 +28,19 @@ func matchFloat64(a, b, threshold float64) bool {
 	return math.Abs(a-b) <= threshold
 }
 
+// MatchingRegexp can be passed to TestCase.Puts to match a any string that
+// matches a regexp pattern. If the pattern is not a valid regexp, the test will
+// panic.
+type MatchingRegexp struct{ Pattern string }
+
+func matchRegexp(p, s string) bool {
+	matched, err := regexp.MatchString(p, s)
+	if err != nil {
+		panic(err)
+	}
+	return matched
+}
+
 type errorMatcher interface{ matchError(error) bool }
 
 // AnyError is an error that can be passed to TestCase.Throws to match any

pkg/eval/mods/path/path.go

@@ -184,13 +184,19 @@ func isRegular(path string) bool {
 //elvdoc:fn temp-dir
 //
 // ```elvish
-// temp-dir &dir=$dir $pattern?
+// temp-dir &dir='' $pattern?
 // ```
 //
-// Create a unique directory and output its name. The &dir option determines where the directory
-// will be created, and its default value is appropriate for your system. The `$pattern` value is
-// optional. If omitted it defaults to `elvish-*`. The last star in the pattern is replaced by a
-// random string. It is your responsibility to remove the (presumably) temporary directory.
+// Creates a new directory and outputs its name.
+//
+// The &dir option determines where the directory will be created; if it is an
+// empty string (the default), a system-dependent directory suitable for storing
+// temporary files will be used. The `$pattern` argument determins the name of
+// the directory, where the last star will be replaced by a random string; it
+// defaults to `elvish-*`.
+//
+// It is the caller's responsibility to remove the directory if it is intended
+// to be temporary.
 //
 // ```elvish-transcript
 // ~> path:temp-dir
@@ -228,17 +234,21 @@ func tempDir(opts mktempOpt, args ...string) (string, error) {
 //elvdoc:fn temp-file
 //
 // ```elvish
-// temp-file [&dir=$dir] [$pattern]
+// temp-file &dir='' $pattern?
 // ```
 //
-// Create a unique file and output a [file](language.html#file) object opened for reading and
-// writing. The &dir option determines where the directory will be created, and its default value is
-// appropriate for your system. The `$pattern` value is optional. If omitted it defaults to
-// `elvish-*`. The last star in the pattern is replaced by a random string. It is your
-// responsibility to remove the (presumably) temporary file.
+// Creates a new file and outputs a [file](language.html#file) object opened
+// for reading and writing.
 //
-// You can use [`fclose`](builtin.html#fclose) to close the file. You can use `$f[name]` to extract
-// the name of the file so it can be used as an argument for another command; e.g., `rm`.
+// The &dir option determines where the file will be created; if it is an
+// empty string (the default), a system-dependent directory suitable for storing
+// temporary files will be used. The `$pattern` argument determins the name of
+// the file, where the last star will be replaced by a random string; it
+// defaults to `elvish-*`.
+//
+// It is the caller's responsibility to close the file with
+// [`file:close`](file.html#close). The caller should also remove the file if it
+// is intended to be temporary (with `rm $f[name]`).
 //
 // ```elvish-transcript
 // ~> f = path:temp-file

pkg/eval/vals/index.go

@@ -35,36 +35,16 @@ func (err noSuchKeyError) Error() string {
 	return "no such key: " + Repr(err.key, NoPretty)
 }
 
-// TODO: Replace this with a a generalized introspection mechanism based on PseudoStructMap for
-// *os.File objects so that commands like `keys` also work on those objects.
-var errInvalidOsFileIndex = errors.New("invalid index for a File object")
-
-func indexOsFile(f *os.File, k interface{}) (interface{}, error) {
-	switch k := k.(type) {
-	case string:
-		switch {
-		case k == "fd":
-			return int(f.Fd()), nil
-		case k == "name":
-			return f.Name(), nil
-		default:
-			return nil, errInvalidOsFileIndex
-		}
-	default:
-		return nil, errInvalidOsFileIndex
-	}
-}
-
 // Index indexes a value with the given key. It is implemented for the builtin
-// type string, the List type, StructMap types, and types satisfying the
-// ErrIndexer or Indexer interface (the Map type satisfies Indexer). For other
-// types, it returns a nil value and a non-nil error.
+// type string, *os.File, List, StructMap and PseudoStructMap types, and types
+// satisfying the ErrIndexer or Indexer interface (the Map type satisfies
+// Indexer). For other types, it returns a nil value and a non-nil error.
 func Index(a, k interface{}) (interface{}, error) {
 	switch a := a.(type) {
 	case string:
 		return indexString(a, k)
 	case *os.File:
-		return indexOsFile(a, k)
+		return indexFile(a, k)
 	case ErrIndexer:
 		return a.Index(k)
 	case Indexer:
@@ -84,6 +64,16 @@ func Index(a, k interface{}) (interface{}, error) {
 	}
 }
 
+func indexFile(f *os.File, k interface{}) (interface{}, error) {
+	switch k {
+	case "fd":
+		return int(f.Fd()), nil
+	case "name":
+		return f.Name(), nil
+	}
+	return nil, NoSuchKey(k)
+}
+
 func indexStructMap(a StructMap, k interface{}) (interface{}, error) {
 	fieldName, ok := k.(string)
 	if !ok || fieldName == "" {

pkg/eval/vals/match.go

@@ -1,24 +0,0 @@
-package vals
-
-import (
-	"regexp"
-)
-
-// MatchesRegexp returns whether The first value matches the second value interpreted as a regexp.
-// Both bytes must be a string.
-func MatchesRegexp(x, y interface{}) bool {
-	val, ok := x.(string)
-	if !ok {
-		return false
-	}
-	pat, ok := y.(string)
-	if !ok {
-		return false
-	}
-
-	matched, err := regexp.MatchString(pat, val)
-	if err != nil {
-		return false
-	}
-	return matched
-}