checking latest version in version control - ant

Question

i am currently writing an ANT script which will include some intelligence to check for things. I am using SnapshotCM from True Blue Software as my version control and using CruiseControl as a framework for my nightly build.
Basically, I will need to always check for the latest version found in my version control and execute commands. In this case here is an example:
<project name="nightly_build" default="main" basedir="checkout">
<target name="init">
<property file="initial.properties"/>
</target>
<target name="main" depends="init">
<!-- need some code to set variable -->
<!-- need some code to increment variable -->
<!-- need some code here to check for the latest version -->
<exec executable="C:/Program Files/True Blue Software/SnapshotCM/wco.exe">
<arg line='-f -R "C:/Work/7.10.000_Tip/7.10.000_Tip_GUI_TEST/"'/>
</exec>
</target>
</project>
In the code above, I will load the "initial.properties" file.
The algorithm should be as follow:
load the initial properties file
get the build_number
increment build_number by 1 (let this new variable be X)
if X is found, increament X by 1 (if not found jump to 6.)
if X is found, repeat 4 (until X cannot be found)
else use the build number inside the <arg line ='-f -R "C:/..../7.10.100.X..../"'/>
The initial.properties file is as follow:
Major_Version=7
Minor_Version=10
Project_Number=100
Build_Number=036
Product_Version=${Major_Version}.${Minor_Version}.${Project_Number}.${Build_Number}
can anyone guide me on that?

Answer 1

Ant is not a programming language. It's a dependency matrix language.
That means you don't specify execution order in Ant. Ant will calculate the order it needs to run the targets. It also means Ant doesn't have the ability to do loops, or even change the value of a property once it is set.
There are a few packages that build upon Ant. The old standby is the Antcontrib. Antcontrib has the concept of variables which are like mutable properties. It also has various looping structures. However, I'm not sure if the <foreach> or <for> tasks will do what you want...
Searching sequentially for the next build number is something you can do in a shell script. In fact, I highly recommend this.
I use Ant for builds only and keep my CM functions outside of my build.xml file. Instead, I rely on my build system to do everything that's not related to the build itself. This includes checking out the code, saving the artifacts, and compiling unit tests. This way, if I change the way I use my continuous build system or my version control system, I don't have to modify my build.xml files.