Hi Tapestry Users,
tl;dr
i print nice strings for enum values. i'm adding some logic which adds
string display beautification. is this how/why i would create a service to
inject my "enum-to-string-beautifier-helper-service" into page classes to
use the methods in tml (forms).
Disclaimer: I'm not going for a gold medal for efficiency atm. Only 3
people will use my app.
+ you guys get to see how my head plugs away in tapestry :) I just want to
know if I'm approaching this in a more or less okay way.
I proudly admit(!!) that I have minimal repeated code that I want to
reduce. 3 methods copy+pasted.
I want to make a tapestry service out of it - a plain and boring converting
string service for an enum with tiny logic involved (or added later).
I have an entity - "Subnet"
It has an enum field of type Netmask which looks like this:
public enum Netmask{
MASK24("255.255.255.0 /24"),
MASK25("255.255.255.0 /25"),
MASK26("255.255.255.0 /26"),
MASK27("255.255.255.0 /27"),
MASK28("255.255.255.0 /28"),
MASK29("255.255.255.0 /29"),
MASK30("255.255.255.0 /30"),
MASK31("255.255.255.0 /31"),
MASK32("255.255.255.0 /32");
}
This Netmask enum is used in a Select - i.e. when "creating a new subnet"
and when "splitting a subnet" I allow only lesser subnet values to be
displayed and therefore "select"-ed e.g. MASK24 > MASK25 > MASK26.....>
MASK32
In my form for creation of a subnet, I've copy+pasted my handy utility
string conversion methods to the "splitting a subnet" tapestry page class,
therefore starting a maintenance headache.
//this method is for select component text beautification
public String convertNetmask(Netmask n){
switch(n){
case MASK24:
return "255.255.255.0 /24";
case MASK25:
return "255.255.255.128 /25";
case MASK26:
return "255.255.255.192 /26";
case MASK27:
return "255.255.255.224 /27";
case MASK28:
return "255.255.255.240 /28";
case MASK29:
return "255.255.255.248 /29";
case MASK30:
return "255.255.255.252 /30";
case MASK31:
return "255.255.255.254 /31";
case MASK32:
return "255.255.255.255 /32";
default:
return "NOT SET";
}
}
//this method is used when displaying in a table
//the subnet's network address with mask e.g. "192.168.0.0 /24"
public String convertNetmaskStrokeOnly(Netmask n){
switch(n){
case MASK24:
return "/24";
case MASK25:
return "/25";
case MASK26:
return "/26";
case MASK27:
return "/27";
case MASK28:
return "/28";
case MASK29:
return "/29";
case MASK30:
return "/30";
case MASK31:
return "/31";
case MASK32:
return "/32";
default:
return "NOT SET";
}
In my tempaltes I have a template displaying Subnets (not a beandisplay) I
like total control :)
<td>${currentSubnet.networkAddress}
${convertNetmaskStrokeOnly(currentSubnet.mask)}</td>
<td>${convertNetmask(currentSubnet.mask)}</td>
This displays something like
| 192.168.0.0 /24 | 255.255.255.0 /24 |
| 192.168.100.0 /28 | 255.255.255.240 /28|
It's a 6 or 7/10 for manageability/simplicity apart from code copy+paste
for extra page classes introducing extra maintenance, but that is being
quite generous.
Now I've added the "splitting a subnet" part and I have this hideous
method, which again is readable for a junior or perl/php/sys-admin type.
public Netmask[] usableNetmasks(Netmask n) {
Netmask[] for24 = {MASK25, MASK26, MASK27, MASK28, MASK29, MASK30,
MASK31, MASK32};
Netmask[] for25 = {MASK26, MASK27, MASK28, MASK29, MASK30, MASK31,
MASK32};
Netmask[] for26 = {MASK27, MASK28, MASK29, MASK30, MASK31, MASK32};
Netmask[] for27 = {MASK28, MASK29, MASK30, MASK31, MASK32};
Netmask[] for28 = {MASK29, MASK30, MASK31, MASK32};
Netmask[] for29 = {MASK30, MASK31, MASK32};
Netmask[] for30 = {MASK31, MASK32};
Netmask[] for31 = {MASK32};
Netmask[] for32 = {};
switch (n) {
case MASK24:
return for24;
case MASK25:
return for25;
case MASK26:
return for26;
case MASK27:
return for27;
case MASK28:
return for28;
case MASK29:
return for29;
case MASK30:
return for30;
case MASK31:
return for31;
default:
return for32;
}
}
I use this method in a form's select (with a zone) like so:
<tr>
<td>Select</td>
<td><t:label for="subnetMask"/><t:select
t:id="subnetMask" t:model="usableNetmasks(addressSelected.mask)"
t:zone="previewZone"/></td>
</tr>
And it works great!
I'm now looking at reversing the splitting process = to join subnets
together. I'm starting to see a pattern here. Whenever I want to do
something with my subnets, I'm going to want to muck around with
beautifying what a subnet looks like and massaging the model for display or
something.
Is this a valid (but maybe no super elegant) service to create....string
conversion/display service for a netmask.
e.g. some pseudo code
public interface NetmaskDisplayHelper {
String convertNetmask(Netmask n);
String convertNetmaskStrokeOnly(Netmask n);
String usableNetmasks(Netmask n);
}
public class NetmaskDisplayHelperImplByChris{
//copy+paste my repeated code here
}
then in AppModule do the binding
binder.bind(NetmaskDisplayHelper.class,
NetmaskDisplayHelperImplByChris.class);
In the page classes
@Inject the NetmaskDisplayHelper
and from the templates somehow call the services, as per the tml snippets
above.
/HUGE-QUESTION-MARK!
Thanks for reading!!! Feedback welcome. Condescending, patronising AND
humourous comments accepted as well :)
Cheers
Chris
P.S. I've gone down to MASK16, so if you know your networking - imagine a
&*$%load of code I scroll past!!
Apache net utils is bloody good too btw.
