MSBuild conditional constructs
MSBuild provides a mechanism for either/or processing with the Choose, When, and Otherwise elements.
Use the Choose element
The Choose
element contains a series of When
elements with Condition
attributes that are tested in order from top to bottom until one evaluates to true
. If more than one When
element evaluates to true
, only the first one is used. An Otherwise
element, if present, is evaluated if no condition on a When
element evaluates to true
.
Choose
elements can be used as child elements of Project
, When
and Otherwise
elements. When
and Otherwise
elements can have ItemGroup
, PropertyGroup
, or Choose
child elements.
Example
The following example uses the Choose
and When
elements for either/or processing. The properties and items for the project are set depending on the value of the Configuration
property.
<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003" >
<PropertyGroup>
<Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
<OutputType>Exe</OutputType>
<RootNamespace>ConsoleApplication1</RootNamespace>
<AssemblyName>ConsoleApplication1</AssemblyName>
<WarningLevel>4</WarningLevel>
</PropertyGroup>
<Choose>
<When Condition=" '$(Configuration)'=='Debug' ">
<PropertyGroup>
<DebugSymbols>true</DebugSymbols>
<DebugType>full</DebugType>
<Optimize>false</Optimize>
<OutputPath>.\bin\Debug\</OutputPath>
<DefineConstants>DEBUG;TRACE</DefineConstants>
</PropertyGroup>
<ItemGroup>
<Compile Include="UnitTesting\*.cs" />
<Reference Include="NUnit.dll" />
</ItemGroup>
</When>
<When Condition=" '$(Configuration)'=='retail' ">
<PropertyGroup>
<DebugSymbols>false</DebugSymbols>
<Optimize>true</Optimize>
<OutputPath>.\bin\Release\</OutputPath>
<DefineConstants>TRACE</DefineConstants>
</PropertyGroup>
</When>
</Choose>
<!-- Rest of Project -->
</Project>
In this example, a condition on a compiler constant DEFINED_CONSTANT
is used. These definitions are included in the DefineConstants
property. The regular expression is used to match the exact constant in a semicolon-separated list.
<Choose>
<When Condition="$([System.Text.RegularExpressions.Regex]::IsMatch(
$(DefineConstants), '^(.*;)*DEFINED_CONSTANT(;.*)*$'))">
<!-- When DEFINED_CONSTANT is defined. -->
</When>
<!-- other conditions -->
</Choose>
See also
प्रतिक्रिया
https://aka.ms/ContentUserFeedback.
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