Ego is an ERb style templating language for Go. It works by transpiling templates into pure Go and including them at compile time. These templates are light wrappers around the Go language itself.
To install ego:
$ go get github.com/benbjohnson/ego/cmd/egoThen run ego on a directory. Recursively traverse the directory structure and compile all .ego files.
$ ego mypkgAll ego files found in a package are compiled and written to a single ego.go file. The name of the directory is used as the package name.
An ego template is made up of several types of blocks:
-
Code Block - These blocks execute raw Go code:
<% var foo = "bar" %> -
Print Block - These blocks print a Go expression. They use
html.EscapeStringto escape it before outputting:<%= myVar %> -
Raw Print Block - These blocks print a Go expression raw into the HTML:
<%== "<script>" %> -
Header Block - These blocks allow you to import packages:
<%% import "encoding/json" %%> -
Declaration Block - This block defines the function signature for your template.
A single declaration block should exist at the top of your template and accept an w io.Writer and return an error. Other arguments can be added as needed. A function receiver can also be used.
<%! func MyTmpl(w io.Writer) error %>
Below is an example ego template for a web page:
<%! func MyTmpl(w io.Writer, u *User) error %>
<%% import "strings" %%>
<html>
<body>
<h1>Hello <%= strings.TrimSpace(u.FirstName) %>!</h1>
<p>Here's a list of your favorite colors:</p>
<ul>
<% for _, colorName := range u.FavoriteColors { %>
<li><%= colorName %></li>
<% } %>
</ul>
</body>
</html>
Once this template is compiled you can call it using the definition you specified:
myUser := &User{
FirstName: "Bob",
FavoriteColors: []string{"blue", "green", "mauve"},
}
var buf bytes.Buffer
err := mypkg.MyTmpl(&buf, myUser)Unlike other runtime-based templating languages, ego does not support ad hoc templates. All templates must be generated before compile time.
Ego does not attempt to provide any security around the templates. Just like regular Go code, the security model is up to you.