How to set 'condition' using a condition stored in a property?

问题

I have a condition such as 'a==1' stored in property $(c) and I wanna used it as the condition for task Message like below code:

  <PropertyGroup>
    <aa>1>2</aa>
  </PropertyGroup>

  <Target Name="t">
    <Message Text="122333" Condition="$(aa)" />
  </Target>

Error was raised! So, how can I do it? Please help!

回答1:

You can easily use property values for evaluating conditions. Here is an example:

<PropertyGroup>
    <aa>1</aa>
</PropertyGroup>

<Target Name="Build">
    <Message Text="Some text" Condition=" $(aa) &lt; 2 " />
</Target>

Note that:

• Property values are strings, you must evaluate the condition in the Condition attribute. See MSDN Docs on evaluating conditions.
• You must escape XML characters (replace < with < )

来源：https://stackoverflow.com/questions/2499253/how-to-set-condition-using-a-condition-stored-in-a-property