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Assembly.LoadFrom Method (String)

Loads an assembly given its file name or path.

Namespace: System.Reflection
Assembly: mscorlib (in mscorlib.dll)

public static Assembly LoadFrom (
	string assemblyFile
)
public static Assembly LoadFrom (
	String assemblyFile
)
public static function LoadFrom (
	assemblyFile : String
) : Assembly
Not applicable.

Parameters

assemblyFile

The name or path of the file that contains the manifest of the assembly.

Return Value

The loaded assembly.

Exception typeCondition

ArgumentNullException

assemblyFile is a null reference (Nothing in Visual Basic).

FileNotFoundException

assemblyFile is not found, or the module you are trying to load does not specify a filename extension.

FileLoadException

A file that was found could not be loaded.

BadImageFormatException

assemblyFile is not a valid assembly.

-or-

Version 2.0 or later of the common language runtime is currently loaded and assemblyFile was compiled with a later version.

SecurityException

A codebase that does not start with "file://" was specified without the required WebPermission.

ArgumentException

The assemblyFile parameter is an empty string ("").

PathTooLongException

The assembly name is longer than MAX_PATH characters.

The assemblyFile parameter must refer to a URI without escape characters. This method supplies escape characters for all invalid characters in the URI.

NoteNote:

File transfer protocol (FTP) is not supported. If the URI supplied for assemblyFile is an FTP address, the assembly is not loaded. No exception is thrown.

assemblyFile is relative to the current directory, and the assembly is loaded into the domain of the caller.

Assemblies can be loaded into one of three contexts, or can be loaded without context:

  • The load context contains assemblies found by probing: in the GAC, in a host assembly store if the runtime is hosted, or in the ApplicationBase and PrivateBinPath of the application domain. Most overloads of the Load method load assemblies into this context.

  • The load-from context contains assemblies for which the user provided a path not included in the directories searched by probing. LoadFrom, CreateInstanceFrom, and ExecuteAssembly are examples of methods that load by path.

  • The reflection-only context contains assemblies loaded with the ReflectionOnlyLoad and ReflectionOnlyLoadFrom methods; code in these contexts cannot be executed.

  • If the user generated or found the assembly, it is not in any context. This applies to assemblies loaded using overloads of the Load method that specify a byte array containing an assembly, and to transient dynamic assemblies created with reflection emit and not saved to disk.

The load-from context allows an assembly to be loaded from a path not included in probing, and yet allows dependencies on that path to be found and loaded because the path information is maintained by the context.

The LoadFrom method has the following disadvantages. Consider using Load instead.

  • If an assembly with the same identity is already loaded, LoadFrom returns the loaded assembly even if a different path was specified.

  • If an assembly is loaded with LoadFrom, and later an assembly in the load context attempts to load same the assembly by display name, the load attempt fails. This can occur when an assembly is de-serialized.

  • If an assembly is loaded with LoadFrom, and the probing path includes an assembly with the same identity but a different location, an InvalidCastException, MissingMethodException, or other unexpected behavior can occur.

  • LoadFrom demands FileIOPermissionAccess.Read and FileIOPermissionAccess.PathDiscovery, or WebPermission, on the specified path.

  • If a native image exists for assemblyFile, it is not used. The assembly cannot be loaded as domain neutral.

  • In the .NET Framework version 1.0 and 1.1, policy is not applied.

The following example loads an assembly given its file name or path.

Assembly SampleAssembly;
SampleAssembly = Assembly.LoadFrom("c:\\Sample.Assembly.dll");
// Obtain a reference to a method known to exist in assembly.
MethodInfo Method = SampleAssembly.GetTypes()[0].GetMethod("Method1");
// Obtain a reference to the parameters collection of the MethodInfo instance.
ParameterInfo[] Params = Method.GetParameters();
// Display information about method parameters.
// Param = sParam1
//   Type = System.String
//   Position = 0
//   Optional=False
foreach (ParameterInfo Param in Params)
{
    Console.WriteLine("Param=" + Param.Name.ToString());
    Console.WriteLine("  Type=" + Param.ParameterType.ToString());
    Console.WriteLine("  Position=" + Param.Position.ToString());
    Console.WriteLine("  Optional=" + Param.IsOptional.ToString());
}

  • FileIOPermission  for reading a URI that begins with "file://". Associated enumeration: FileIOPermissionAccess.Read
  • WebPermission  for reading a URI that does not begin with "file://".

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0
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