“预期类型” PowerShell附加型代码块中的错误。 dllimport，Windows已知文件夹

Question

我尝试.ps1

Add-Type -TypeDefinition @'
using System;       // IntPtr
using System.Runtime;       // guid Type
using System.Runtime.InteropServices;       // DllImport

public class Win32 {
    public static class KnownFolderId {
        public static readonly Guid Desktop = new(0xB4BFCC3A, 0xDB2C, 0x424C, 0xB0, 0x29, 0x7F, 0xE9, 0x9A, 0x87, 0xC6, 0x41);
    }

    [DllImport("shell32.dll")] static extern int SHGetKnownFolderPath(
        [MarshalAs(UnmanagedType.LPStruct)] Guid rfid,
        uint dwFlags,
        IntPtr hToken,
        out IntPtr ppszPath
    );
                
    public static string? GetKnownFolderPath() {
        IntPtr ppszPath = default;
        try {
            int hr = SHGetKnownFolderPath(Win32.KnownFolderId.Desktop, 0, IntPtr.Zero, out ppszPath);
            Marshal.ThrowExceptionForHR(hr); // alternatively, check success with hr >= 0
            return Marshal.PtrToStringUni(ppszPath);
        }
        finally {
            Marshal.FreeCoTaskMem(ppszPath);
        }
    }

}
'@
[Win32]::GetKnownFolderPath() | write-host

read-host 'end'

，当然要获取此

Type expected
<<..>>\h1c5k4r2.0.cs(5) : public static class KnownFolderId {
<<..>>\h1c5k4r2.0.cs(6) : >>>     public static readonly Guid Desktop = new(0xB4BFCC3A,<<..>>

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Answer 1

您使用的是 add-type 在 Windows PowerShell 中不支持，特别是：

• new（...），无类型名称的构造函数调用 - 替换为新GUID（...）

  


• default to to to指示类型的默认值 - 替换为intptr.zero。

• 字符串？，一个无效的注释 - 删除？

因此，使用以下内容：

Add-Type -TypeDefinition @'
using System;       // IntPtr
using System.Runtime;       // guid Type
using System.Runtime.InteropServices;       // DllImport

public class Win32 {
    public static class KnownFolderId {
        public static readonly Guid Desktop = new Guid(0xB4BFCC3A, 0xDB2C, 0x424C, 0xB0, 0x29, 0x7F, 0xE9, 0x9A, 0x87, 0xC6, 0x41);
    }

    [DllImport("shell32.dll")] static extern int SHGetKnownFolderPath(
        [MarshalAs(UnmanagedType.LPStruct)] Guid rfid,
        uint dwFlags,
        IntPtr hToken,
        out IntPtr ppszPath
    );
                
    public static string GetKnownFolderPath() {
        IntPtr ppszPath = IntPtr.Zero;
        try {
            int hr = SHGetKnownFolderPath(Win32.KnownFolderId.Desktop, 0, IntPtr.Zero, out ppszPath);
            Marshal.ThrowExceptionForHR(hr); // alternatively, check success with hr >= 0
            return Marshal.PtrToStringUni(ppszPath);
        }
        finally {
            Marshal.FreeCoTaskMem(ppszPath);
        }
    }

}
'@

[Win32]::GetKnownFolderPath()

---

注意：

• in powershell（core）7+， add-type 确实支持这些语言功能。

  
  

• 在那里，唯一需要的更改是将#nullable enable放在源代码的第一行，以启用无效的注释。