How can i find/stop if the file is already included in nant while including a build file

I have 4 files say: A.build, B.build, C.build & Common.build.

B.build & C.build includes Common.build.

I am suppose to call file A.build which internally calls B.build & C.Build. When i try ru开发者_JAVA技巧nning this file its give me error Common.build file already included.

Is there any way I can stop including a build file if it's already included....

Nant should be ok with the same file being included more than once, although it can have problems if you use use different cases in the name (such as 'hello.include' and 'HELLO.include' for example). Have a look at this answer for more details.