publish urls

examples.txt

@@ -53,7 +53,7 @@ Defer
 # Elapsed Time
 # Random Numbers
 # Number Parsing
-# URLs
+URLs
 SHA1 Hashes
 Base64 Encoding
 # Reading Files

examples/urls/urls.go

@@ -1,3 +1,6 @@
+// URLs provide a [uniform format for locating resources](...).
+// Here's how to parse URLs in Go.
+
 package main
 
 import "fmt"
@@ -5,22 +8,47 @@ import "net/url"
 import "strings"
 
 func main() {
+
+    // We'll parse this example URL, which includes a 
+    // scheme, authentication info, host, port, path,
+    // query params, and query fragment.
     s := "postgres://user:pass@host.com:5432/path?k=v#f"
+
+    // Parse the URL and ensure there are no errors.
     u, err := url.Parse(s)
     if err != nil {
         panic(err)
     }
+
+    // Access to the scheme is straightforward.
     fmt.Println(u.Scheme)
+
+    // `User` contains all authentication info; call
+    // `Username` and `Password` on this for individual
+    // values.
     fmt.Println(u.User)
     fmt.Println(u.User.Username())
     p, _ := u.User.Password()
     fmt.Println(p)
+
+    // The `Host` contains both the hostname and the port,
+    // if present. `Split` the `Host` manually to extract
+    // the port.
     fmt.Println(u.Host)
-    split := strings.Split(u.Host, ":")
-    fmt.Println(split[0])
-    fmt.Println(split[1])
+    h := strings.Split(u.Host, ":")
+    fmt.Println(h[0])
+    fmt.Println(h[1])
+
+    // Here we extract the `path` and the fragment after
+    // the `#`.
     fmt.Println(u.Path)
     fmt.Println(u.Fragment)
+
+    // To get query params in a string of `k=v` format,
+    // use `RawQuery`. You can also parse query params
+    // into a map. The parsed query param maps are from
+    // strings to slices of strings, so index into `[0]`
+    // if you only want the first value.
     fmt.Println(u.RawQuery)
     m, _ := url.ParseQuery(u.RawQuery)
     fmt.Println(m)

examples/urls/urls.sh

@@ -1,4 +1,6 @@
-$ go run urls.go
+# Running our URL parsing program shows all the different
+# pieces that we extracted.
+$ go run urls.go 
 postgres
 user:pass
 user
@@ -7,7 +9,7 @@ host.com:5432
 host.com
 5432
 /path
-frag
+f
 k=v
 map[k:[v]]
 v