prep for first renumber

README.md

@@ -1,3 +1,11 @@
 ## gbe-book
 
 Go by Example book source.
+
+
+### Reordering
+
+```bash
+$ mate tool/index.txt
+$ go run tool/reorder.go
+```

tool/index.txt

@@ -0,0 +1,96 @@
+hello-world
+values
+variables
+mutation
+literal
+constant
+reading-input
+for
+if-else
+case
+arrays
+sum
+range
+floats
+slices
+maps
+ok-guards
+nesting
+functions
+returns
+varargs
+closures
+recursion
+defer
+panic
+recover
+values
+pointers
+new
+structs
+fields
+methods
+embedding
+interfaces
+goroutines
+concurrency
+channels
+buffering
+directions
+synchronization
+select
+timeout
+string-fns
+bytes
+args
+burstable-rate-limiting
+dns
+elapsed
+email
+enumerable
+env
+epoch
+errors
+exec
+exits
+file-open
+file-read
+file-write
+flags
+http-client-basic
+http-client
+http-server-basic
+http-server-canonical-host
+http-server-graceful-shutdown
+http-server-log
+http-server-middleware
+http-server-routing
+http-server-static-dynamic
+http-server-static-select
+http-server-static
+http-server-status-code
+http-server
+https-client
+https-server
+json
+number-parsing
+postgres
+rand
+rate-limiting
+redis
+regexs
+scatter-gather
+sha1
+signals
+sort
+sortby
+spawn
+string-formatting
+tcp-client
+tcp-server
+tickers
+time
+timers
+url
+users
+worker-pool

tool/renumber.go

@@ -0,0 +1,44 @@
+// Renumber the .go content files according to the
+// order in index.txt.
+
+package main
+
+import (
+    "fmt"
+    "io/ioutil"
+    "strings"
+    "regexp"
+)
+
+func main() {
+    // read names of source files
+    sourceNames := make([]string, 0)
+    sourceMap := make(map[string]string)
+    fileInfos, dirErr := ioutil.ReadDir("./")
+    if dirErr != nil { panic(dirErr) }
+    baseTrimmer, _ := regexp.Compile("([0-9x]+-)|(.go)")
+    for _, fi := range fileInfos {
+        baseName := baseTrimmer.ReplaceAllString(fi.Name(), "")
+        if baseName != ".git" && baseName != "tool" && baseName != "README.md" {
+            sourceNames = append(sourceNames, baseName)
+            sourceMap[baseName] = fi.Name()
+        }
+    }
+
+    // read names from index
+    indexBytes, idxErr := ioutil.ReadFile("tool/index.txt")
+    if idxErr != nil { panic (idxErr) }
+    indexNames := strings.Split(string(indexBytes), "\n")
+    
+    // sanity check two lists
+    if len(sourceNames) != len(indexNames) {
+        panic("mismatched names")
+    }
+    
+    // rename some stuff
+    for index, indexName := range indexNames {
+        oldName := sourceMap[indexName]
+        newName := fmt.Sprintf("%d-%s.go", index+1, indexName)
+        os.Rename(oldName, newName)
+    }
+}