Adding debugMode functionality. Related to 15

README.md

@@ -60,6 +60,46 @@ Most functions have help defined so you can use ```get-help``` on most commands
 
 We have not yet developed the NuGet package yet but will be working on it soon.
 
+## Debug mode
+In many cases after a build it would be helpful to be able to answer questions like the following.
+
+ - What is the value of x property?
+ - What is the value of y property?
+ - What would the expression '@(Compile->'%(FullPath)') be?
+
+But when you call msbuild.exe the project that is built is created in memory and trashed at the end of the process. ```Invoke-MSBuild``` now has a way that you can invoke your build and then have a _"handle"_ to your project that was built. This allows you to ask questions like the following. To enable this you just need to pass in the ```-debugMode``` switch to ```Invoke-MSBuild``` (_Note: this is actively under development so if you run into an problems please open an issue_). Here are some examples of what you can do.
+
+```
+PS> $bResult = Invoke-MSBuild .\temp.proj -debugMode
+
+PS> $bResult.EvalProperty('someprop')
+default
+
+PS> $bResult.EvalItem('someitem')
+temp.proj
+
+PS> $bResult.ExpandString('$(someprop)')
+default
+
+PS> $bResult.ExpandString('@(someitem->''$(someprop)\%(Filename)%(Extension)'')')
+default\temp.proj
+```
+
+You can get full access to the [ProjectInstance](http://msdn.microsoft.com/en-us/library/microsoft.build.execution.projectinstance(v=vs.121).aspx) object with the ProjectInstance property.
+
+More functionality is available via the ProjectInstance object.
+``` 
+PS> $bResult.ProjectInstance.GetItems('someitem').EvaluatedInclude
+temp.proj
+```
+
+You can get the [BuildResuilt](http://msdn.microsoft.com/en-us/library/microsoft.build.execution.buildresult(v=vs.121).aspx) via the BuildResult parameter.
+
+```
+PS> $bResult.BuildResult.OverallResult
+Failure
+```
+
 # Reporting Issues
 To report any issues please create an item on the [issues page](https://github.com/sayedihashimi/psbuild/issues/new).
 

src/psbuild.psm1

@@ -80,7 +80,7 @@ function Set-MSBuild{
 }
 
 <#
-.SYNOPSIS  
+.SYNOPSIS
 	Can be used to invoke MSBuild. If the msbuildPath parameter is not passed in
     the Get-MSBuild function will be called to determine the version of MSBuild
     which should be used.
@@ -333,13 +333,30 @@ function Invoke-MSBuild{
                         $brd)
                     $psbuildResult = New-PSBuildResult -buildResult $buildResult -projectInstance $projectInstance
 
+                    $script:lastDebugBuildResult = $psbuildResult
                     return $psbuildResult
                 }
             }
         }
     }
 }
 
+<#
+.SYNOPSIS
+    When you call Invoke-MSBuild with the -debugMode flag an object is returned that is the build result.
+    If you did not save this object you can use this method to reterive that last build result.
+
+.EXAMPLE
+    $lastResult = Get-PSBuildLastDebugBuildResult
+#>
+function Get-PSBuildLastDebugBuildResult{
+    [cmdletbinding()]
+    param()
+    process{
+        return $script:lastDebugBuildResult
+    }
+}
+
 function New-PSBuildResult{
     [cmdletbinding()]
     param(
@@ -365,6 +382,56 @@ function New-PSBuildResult{
             ProjectInstance = $projectInstance
         }
 
+        $result | Add-Member -MemberType ScriptMethod -Name EvalProperty -Value {
+            [cmdletbinding()]
+            param(
+                [Parameter(
+                    Mandatory=$true)]
+                [string]
+                $propName)
+            if($this.ProjectInstance){
+                $this.ProjectInstance.GetPropertyValue($propName)
+            }
+            else{
+                'project is null'
+            }
+        }
+
+        $result | Add-Member -MemberType ScriptMethod -Name EvalItem -Value {
+            [cmdletbinding()]
+            param(
+                [Parameter(
+                    Mandatory=$true)]
+                [string]
+                $propName)
+            if($this.ProjectInstance){
+                # todo: is there a better way to do this?
+                $expressionToEval = ('@({0})' -f $propName)
+                return $this.ProjectInstance.ExpandString($expressionToEval)
+            }
+            else{
+                'project is null'
+            }
+        }
+
+        $result | Add-Member -MemberType ScriptMethod ExpandString -Value {
+            [cmdletbinding()]
+            param(
+                [Parameter(
+                    Mandatory=$true)]
+                [string]
+                $unexpandedValue
+            )
+            process{
+                if($this.ProjectInstance){
+                    return $this.ProjectInstance.ExpandString($unexpandedValue)
+                }
+                else{
+                    'project is null'
+                }
+            }
+        }
+
         return $result
     }
 }