build: Allow codegen-only to produce the templated main.go (#133)

Fixes #131.

Author: paulsmith

main.go

@@ -349,7 +349,7 @@ func (b *buildCmd) do() error {
 		}
 	}
 
-	if b.parseOnly || b.codeGenOnly {
+	if b.parseOnly {
 		return nil
 	}
 
@@ -360,6 +360,7 @@ func (b *buildCmd) do() error {
 			buildDir:          b.outDir,
 			outFile:           b.outFile,
 			verbose:           b.verbose,
+			codeGenOnly:       b.codeGenOnly,
 		}
 		if err := buildProject(context.Background(), params); err != nil {
 			return fmt.Errorf("building project: %w", err)
@@ -760,6 +761,7 @@ type buildParams struct {
 	buildDir          string
 	outFile           string
 	verbose           bool
+	codeGenOnly       bool
 }
 
 // buildProject builds the Go program made up of the user's compiled .up
@@ -798,6 +800,13 @@ func buildProject(_ context.Context, b buildParams) error {
 		b.outFile = filepath.Join(b.buildDir, "bin", b.projectName)
 	}
 
+	if b.codeGenOnly {
+		if b.verbose {
+			fmt.Printf("codegen only, not building executable\n")
+		}
+		return nil
+	}
+
 	args := []string{"build", "-o", b.outFile, filepath.Join(pkgName, "cmd", b.projectName)}
 	if b.verbose {
 		fmt.Printf("build command: go %s\n", strings.Join(args, " "))