reconstruct outputs everytime

fix browserify#68, browserify#59

- To avoid writing to ended writeStream, outputs will be constructed everytime
- In the scenario that user wanna use outpipe, the `outopt` will be
kept as string, so we can determine the user's attempt in later codes
and do the relavant opperations

index.js

@@ -28,20 +28,6 @@ module.exports = function f (b, opts) {
     var needRecords = !files.length;
 
     var outopt = defined(opts.outputs, opts.output, opts.o);
-    if (outopt && !isarray(outopt)) outopt = [outopt];
-    var outputs = defined(outopt, []).map(function (o) {
-        if (isStream(o)) return o;
-        else return fs.createWriteStream(o);
-    });
-    if (!isarray(outputs) && isStream(outputs)) outputs = [ outputs ];
-    else if (!isarray(outputs)) outputs = [];
-
-    function moreOutputs (file) {
-        if (isarray(outopt)) return [];
-        if (!outopt) return [];
-        var xopts = { env: xtend(process.env, { FILE: file }) };
-        return [ outpipe(outopt, xopts) ];
-    }
 
     opts.objectMode = true;
     opts.raw = true;
@@ -57,6 +43,23 @@ module.exports = function f (b, opts) {
     addHooks();
 
     function addHooks () {
+        var outputs;
+        if (isarray(outopt)) {
+            outputs = outopt.map(function (o) {
+                if (isStream(o)) return o;
+                return fs.createWriteStream(o);
+            });
+        } else {
+            outputs = [];
+        }
+
+        function moreOutputs (file) {
+            if (isarray(outopt)) return [];
+            if (!outopt) return [];
+            var xopts = { env: xtend(process.env, { FILE: file }) };
+            return [ outpipe(outopt, xopts) ];
+        }
+
         b.pipeline.get('record').push(through.obj(function(row, enc, next) {
             if (row.file && needRecords) {
                 files.push(row.file);