Tuesday, December 7, 2004

Escaping ${} in NAnt Scripts

Today I was writing a NAnt script that calls an XSLT, passing in some regular expression replacement arguments so I could use replace occurrences of certain strings in an XML file. The problem I ran into is that the syntax for a regex replacement is ${group}, which is exactly the same as the syntax for a property in a NAnt script. I figured there must be an escape sequence in NAnt that lets you say, “No, I really want a dollar sign and a curly brace - I'm not specifying a property.“ But I tried backslash and the other usual suspects, then searched the web for a while. Nothing.


I banged my head against the problem for a while, and finally came up with this:


<property name="replacement" value="http://localhost/${product.name}-${websafe.version}${'${path}'}" />


It's the ${'${path}'} that actually does the trick: basically, I'm saying, “Use the string literal ${path}.“


I'm pretty sure this will only work in NAnt 0.85 and later, as that's when string literal expressions were introduced.

9 comments:

  1. Thank you for posting this. Like you I tried the usual suspects. A quick google turned up your answer. I appreciate the fact that you took the time to document this, thus saving others time.



    Quick Plug: The book 'Expert .NET Delivery Using NAnt and CruiseControl.NET' by APress is very good... but it does not have this info... thanks Craig.

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  2. Ditto. That helped.

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  3. Glad to be of service.

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  4. Thanks Craig.

    Keep up the great work!!

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  5. Thanks Craig It helped me.

    But one issue i have is i am trying to invoke few services which has "-" in this servicename.When i try to run the NET START Servicename from NAnt script it is not able to reconginize the service. Does this Escaping will introduce any additional spaces in the service name.? I have checked the length of the working service name and the one from the NAnt script. Both shows same.

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  6. I'm not sure. It's been a long time since I've done this: almost five years.

    You could try shelling out to sc instead of net start

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  7. Thanks... This helped me xmlpoke a nlog setting.. of course nlog layout renderes have to be formatted as '${shortdate}'.

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  8. Thanks.
    Doing the same thing as Russ, but for log4net.

    The tips that keep on giving, hey?

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