Changes per feedback

docs/usage.md

@@ -266,6 +266,8 @@ The above syntax is also supported in `deps`.
 
 ## Prevent unnecessary work
 
+### By fingerprinting locally generated files and their sources
+
 If a task generates something, you can inform Task the source and generated
 files, so Task will prevent to run them if not necessary.
 
@@ -321,6 +323,9 @@ tasks:
 
 > TIP: method `none` skips any validation and always run the task.
 
+### Using programmatic checks to indicate a task is up to date.
+
+
 Alternatively, you can inform a sequence of tests as `status`. If no error
 is returned (exit status 0), the task is considered up-to-date:
 
@@ -340,7 +345,8 @@ tasks:
       - test -f directory/file2.txt
 ```
 
-Normally, you would use either `status` or `sources` in combination with
+
+Normally, you would use `sources` in combination with
 `generates` - but for tasks that generate remote artifacts (Docker images,
 deploys, CD releases) the checksum source and timestamps require either
 access to the artifact or for an out-of-band refresh of the `.checksum`
@@ -356,9 +362,13 @@ up-to-date.
 Also, `task --status [tasks]...` will exit with a non-zero exit code if any of
 the tasks are not up-to-date.
 
-If you need a certain set of conditions to be _true_ you can use the
+### Using programmatic checks to cancel execution of an task and it's dependencies
-`preconditions` stanza.  `preconditions` are very similar to `status`
+
-lines except they support `sh` expansion and they SHOULD all return 0.
+In addition to `status` checks, there are also `preconditions` checks, which are
+the logical inverse of `status` checks.  That is, if you need a certain set of
+conditions to be _true_ you can use the `preconditions` stanza.
+`preconditions` are similar to `status` lines except they support `sh`
+expansion and they SHOULD all return 0.
 
 ```yaml
 version: '2'

go.mod

@@ -14,10 +14,8 @@ require (
 	github.com/radovskyb/watcher v1.0.5
 	github.com/spf13/pflag v1.0.3
 	github.com/stretchr/testify v1.3.0
-	golang.org/x/crypto v0.0.0-20180830192347-182538f80094 // indirect
+	golang.org/x/sync v0.0.0-20190423024810-112230192c58
-	golang.org/x/net v0.0.0-20180826012351-8a410e7b638d // indirect
+	golang.org/x/tools/gopls v0.1.3 // indirect
-	golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f
-	golang.org/x/sys v0.0.0-20180831094639-fa5fdf94c789 // indirect
 	gopkg.in/yaml.v2 v2.2.1
 	mvdan.cc/sh v2.6.4+incompatible
 )

go.sum

@@ -33,12 +33,24 @@ github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 golang.org/x/crypto v0.0.0-20180830192347-182538f80094 h1:rVTAlhYa4+lCfNxmAIEOGQRoD23UqP72M3+rSWVGDTg=
 golang.org/x/crypto v0.0.0-20180830192347-182538f80094/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2 h1:VklqNMn3ovrHsnt90PveolxSbWFaJdECFbxSq0Mqo2M=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/net v0.0.0-20180826012351-8a410e7b638d h1:g9qWBGx4puODJTMVyoPrpoxPFgVGd+z1DZwjfRu4d0I=
 golang.org/x/net v0.0.0-20180826012351-8a410e7b638d/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f h1:wMNYb4v58l5UBM7MYRLPG6ZhfOqbKu7X5eyFl8ZhKvA=
 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58 h1:8gQV6CLnAEikrhgkHFbMAEhagSSnXWGV915qUMm9mrU=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20180831094639-fa5fdf94c789 h1:T8D7l6WB3tLu+VpKvw06ieD/OhBi1XpJmG1U/FtttZg=
 golang.org/x/sys v0.0.0-20180831094639-fa5fdf94c789/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a h1:1BGLXjeY4akVXGgbC9HugT3Jv3hCI0z56oJR5vAMgBU=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/tools v0.0.0-20190710153321-831012c29e42 h1:4IOeC7p+OItq3+O5BWkcmVu2uBe3jekXau5S4QZX9DU=
+golang.org/x/tools v0.0.0-20190710153321-831012c29e42/go.mod h1:jcCCGcm9btYwXyDqrUWc6MKQKKGJCWEQ3AfLSRIbEuI=
+golang.org/x/tools/gopls v0.1.3 h1:CB5ECiPysqZrwxcyRjN+exyZpY0gODTZvNiqQi3lpeo=
+golang.org/x/tools/gopls v0.1.3/go.mod h1:vrCQzOKxvuiZLjCKSmbbov04oeBQQOb4VQqwYK2PWIY=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.1 h1:mUhvW9EsL+naU5Q3cakzfE91YhliOondGd6ZrsDBHQE=

internal/status/checksum.go

@@ -46,10 +46,6 @@ func (c *Checksum) IsUpToDate() (bool, error) {
 	return oldMd5 == newMd5, nil
 }
 
-func (t *Checksum) Kind() string {
-	return "checksum"
-}
-
 func (c *Checksum) checksum(files ...string) (string, error) {
 	h := md5.New()
 
@@ -77,7 +73,7 @@ func (c *Checksum) checksum(files ...string) (string, error) {
 	return fmt.Sprintf("%x", h.Sum(nil)), nil
 }
 
-// Value implements the Chcker Interface
+// Value implements the Checker Interface
 func (c *Checksum) Value() (string, error) {
 	return c.checksum()
 }
@@ -87,6 +83,11 @@ func (c *Checksum) OnError() error {
 	return os.Remove(c.checksumFilePath())
 }
 
+// Kind implements the Checker Interface
+func (t *Checksum) Kind() string {
+	return "checksum"
+}
+
 func (c *Checksum) checksumFilePath() string {
 	return filepath.Join(c.Dir, ".task", "checksum", c.normalizeFilename(c.Task))
 }

internal/templater/templater.go

@@ -18,6 +18,10 @@ type Templater struct {
 	err    error
 }
 
+func (r *Templater) RefreshStringMap() {
+	r.strMap = r.Vars.ToStringMap()
+}
+
 func (r *Templater) Replace(str string) string {
 	if r.err != nil || str == "" {
 		return ""

status.go

@@ -32,7 +32,7 @@ func (e *Executor) isTaskUpToDate(ctx context.Context, t *taskfile.Task) (bool,
 		return e.isTaskUpToDateStatus(ctx, t)
 	}
 
-	checker, err := e.GetStatusChecker(t)
+	checker, err := e.getStatusChecker(t)
 	if err != nil {
 		return false, err
 	}
@@ -41,14 +41,14 @@ func (e *Executor) isTaskUpToDate(ctx context.Context, t *taskfile.Task) (bool,
 }
 
 func (e *Executor) statusOnError(t *taskfile.Task) error {
-	checker, err := e.GetStatusChecker(t)
+	checker, err := e.getStatusChecker(t)
 	if err != nil {
 		return err
 	}
 	return checker.OnError()
 }
 
-func (e *Executor) GetStatusChecker(t *taskfile.Task) (status.Checker, error) {
+func (e *Executor) getStatusChecker(t *taskfile.Task) (status.Checker, error) {
 	switch t.Method {
 	case "", "timestamp":
 		return &status.Timestamp{

variables.go

@@ -1,7 +1,6 @@
 package task
 
 import (
-	"io/ioutil"
 	"path/filepath"
 	"strings"
 
@@ -64,30 +63,6 @@ func (e *Executor) CompiledTask(call taskfile.Call) (*taskfile.Task, error) {
 		new.Env[k] = taskfile.Var{Static: static}
 	}
 
-	if len(origTask.Status) > 0 {
-		e := &Executor{
-			Dir:    new.Dir,
-			Stdout: ioutil.Discard,
-			Stderr: ioutil.Discard,
-			Dry:    true,
-		}
-
-		checker, err := e.GetStatusChecker(&new)
-		if err != nil {
-			return nil, err
-		}
-
-		value, err := checker.Value()
-		if err != nil {
-			return nil, err
-		}
-
-		vars[strings.ToUpper(checker.Kind())] = taskfile.Var{Static: value}
-
-		statusTemplater := templater.Templater{Vars: vars}
-		new.Status = statusTemplater.ReplaceSlice(origTask.Status)
-	}
-
 	if len(origTask.Cmds) > 0 {
 		new.Cmds = make([]*taskfile.Cmd, len(origTask.Cmds))
 		for i, cmd := range origTask.Cmds {
@@ -120,5 +95,24 @@ func (e *Executor) CompiledTask(call taskfile.Call) (*taskfile.Task, error) {
 		}
 	}
 
+	if len(origTask.Status) > 0 {
+		checker, err := e.getStatusChecker(&new)
+		if err != nil {
+			return nil, err
+		}
+
+		value, err := checker.Value()
+		if err != nil {
+			return nil, err
+		}
+
+		vars[strings.ToUpper(checker.Kind())] = taskfile.Var{Static: value}
+		// Adding new static variables, requires us to refresh the templaters
+		// cache of the the static values
+		r.RefreshStringMap()
+
+		new.Status = r.ReplaceSlice(origTask.Status)
+	}
+
 	return &new, r.Err()
 }