convert strings to f-strings; clean up btree code; wrap network stuff in try-except

tf_extend.py

@@ -46,19 +46,22 @@ def cmd(args):
     try:
       tf.transfer(args[1],w)
       if cmd=='wc':
-        print("lines: {}\twords: {}\tbytes: {}".format(w.lines, w.words, w.bytes_))
+        print(f"lines: {w.lines}\twords: {w.words}\tbytes: {w.bytes_}")
     except:
       print("file not found: "+args[1])
 
   elif cmd in ('ifconfig','ip'):
     ifc=network.WLAN().ifconfig()
-    print("IP: {}\tmask: {}\tgateway: {}\tDNS: {}".format(*ifc))
+    print(f"IP: {ifc[0]}\tmask: {ifc[1]}\tgateway: {ifc[2]}\tDNS: {ifc[3]}")
 
   elif cmd in ('host','nslookup','dig'):
     if len(args)<2:
       print("syntax: host <domain.name>")
     else:
-      print("host <{}> is at {}".format(args[1],socket.getaddrinfo(args[1],80)[0][-1][0]))
+      try:
+        print(f"host <{args[1]}> is at {socket.getaddrinfo(args[1],80)[0][-1][0]}")
+      except:
+        print("network/DNS not available")
 
   elif cmd=='connect':
     if len(args)<3:
@@ -78,7 +81,7 @@ def cmd(args):
       print("no AP found")
       return True
     for i in s:
-      print("ch: {}\tRSSI: {}\t{}\tSSID: {}".format(i[2],i[3],"open" if i[4]==0 else "",i[0]))
+      print(f"ch: {i[2]}\tRSSI: {i[3]}\t{"open" if i[4]==0 else ""}\tSSID: {i[0]}")
 
   elif cmd=='freq':
     # identify esp32 or esp8266
@@ -90,7 +93,7 @@ def cmd(args):
     if len(args)==1 or args[1] in freqs:
       if len(args)>1:
         machine.freq(int(args[1])*1000000)
-      print("master cpu frequency {}MHz".format(machine.freq()//1000000))
+      print(f"master cpu frequency {machine.freq()//1000000}MHz")
     else:
       print("syntax: freq [ 160 | 80 | 240 ] ")
 
@@ -100,8 +103,8 @@ def cmd(args):
       b=btree.open(f)
       print("Key\t\tValue")
       i=0
-      for w in b:
-        print("{}\t{}".format(w,b[w]))
+      for k,v in b.items():
+        print(f"{k:10}\t{v}")
         i+=1
         if i%30==0:
           r=input("continue? ")
@@ -115,15 +118,15 @@ def cmd(args):
     except OSError:
       print("file not found")
   elif cmd=='free':
-    print("memory used: {}\tmemory free:{}".format(gc.mem_alloc(),gc.mem_free()))
+    print(f"memory used: {gc.mem_alloc()}\tmemory free:{gc.mem_free()}")
   elif cmd=='help':
     print("==Extended commands")
     print("  connect <essid> <password> \tscan")
     print("  ifconfig/ip        \t\thost/dig/nslookup <domain.name>")
-    print("  freq [160 | 80 | 240]\texec <python-filename>")
+    print("  freq [160 | 80 | 240]\t\texec <python-filename>")
     print("  free        \t\t\twc <filename>")
     print("  less/more [-n] <filename>")
-    print("  bt-list <filename>")
+    print("  btree <filename>")
   else: # command not found
     return False
   return True