From 93b1ce745f8df27e20d69c9f78edae5247b5cc79 Mon Sep 17 00:00:00 2001
From: shantuo <sturbo89@gmail.com>
Date: Tue, 11 Jun 2019 15:35:05 -0700
Subject: [PATCH] doc: add guide to use the `wire:"-"` tag (#195)

---
 docs/guide.md | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/docs/guide.md b/docs/guide.md
index a3157ee7..c1a15af8 100644
--- a/docs/guide.md
+++ b/docs/guide.md
@@ -300,6 +300,21 @@ func injectFooBar() FooBar {
 
 And similarly if the injector needed a `*FooBar`.
 
+It is sometimes useful to prevent certain fields from being filled in by the
+injector, especially when passing `*` to `wire.Struct`. You can tag a field with
+`` `wire:"-"` `` to have Wire ignore such fields. For example:
+
+```go
+type Foo struct {
+    mu sync.Mutex `wire:"-"`
+    Bar Bar
+}
+```
+
+When you provide the `Foo` type using `wire.Struct(new(Foo), "*")`, Wire will
+automatically omit the `mu` field. Additionally, it is an error to explicitly
+specify a prevented field as in `wire.Struct(new(Foo), "mu")`.
+
 ### Binding Values
 
 Occasionally, it is useful to bind a basic value (usually `nil`) to a type.