C# IDE0090 'new'表达式可以简化 视觉工作室 2022

Question

我从stackoverflow的一个用户那里改编了这个snmp程序。我在Visual studio 2022中创建了一个新项目，添加了所有依赖项。

当我编译我得到6个IDE0090消息，但我看不出问题是什么。我已将LangVersion设置为10。

https://i.stack.imgur.com/BF5P1.jpg

谁能看出问题是什么吗?

using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using SnmpSharpNet;
namespace Exemple2
{
class Program
{
static void Main(string[] args)
{
/* Get an SNMP Object
*/
SimpleSnmp snmpVerb = new SimpleSnmp("192.168.1.121", 161, "public");
if (!snmpVerb.Valid)
{
Console.WriteLine("Seems that IP or comunauty is not cool");
return;
}

/* Sample of simple Get usage on ifSpeed on interface 10
* TODO : for sure you have to detect the right interface
*/
Oid oidifSpeed = new Oid(".1.3.6.1.2.1.2.2.1.5.10");
/* Getting ifSpeed
*/
Dictionary<Oid, AsnType> snmpDataS = snmpVerb.Get(SnmpVersion.Ver2, new string[] { oidifSpeed.ToString() });
if (snmpDataS != null)
Console.WriteLine("Interface speed "{0}" : {1}", oidifSpeed.ToString(), snmpDataS[oidifSpeed].ToString());
else
Console.WriteLine("Not Glop!");
/* Sample of simple Get usage on ifInOctets on interface 10
* TODO : for sure you have to detect the right interface
*/
Oid oidifInOctets = new Oid(".1.3.6.1.2.1.2.2.1.10.10");
Dictionary<Oid, AsnType> snmpData1;
/* Getting it for the first time
*/
snmpData1 = snmpVerb.Get(SnmpVersion.Ver2, new string[] { oidifInOctets.ToString() });
if (snmpData1 != null)
Console.WriteLine("Number of In octets "{0}" : {1}", oidifInOctets.ToString(), snmpData1[oidifInOctets].ToString());
else
Console.WriteLine("Not Glop!");
int missed = 0;
while (true)
{
if (missed == 0)
{
/* When you detect a non refesh data, keep the last one
*/
snmpData1 = snmpVerb.Get(SnmpVersion.Ver2, new string[] { oidifInOctets.ToString() });
if (snmpData1 != null)
Console.WriteLine("Number of In octets "{0}" : {1}", oidifInOctets.ToString(), snmpData1[oidifInOctets].ToString());
else
Console.WriteLine("Not Glop!");
}
/* Some Wait (less aproximative)
*/
int duration = 5;
System.Threading.Thread.Sleep(duration * 1000); // duration seconds
/* Getting it for the Second time
*/
Dictionary<Oid, AsnType> snmpData2 = snmpVerb.Get(SnmpVersion.Ver2, new string[] { oidifInOctets.ToString() });
if (snmpData2 != null)
Console.WriteLine("Number of In octets "{0}" : {1}", oidifInOctets.ToString(), snmpData2[oidifInOctets].ToString());
else
Console.WriteLine("Not Glop!");
Counter32 I1 = new Counter32();
I1.Set(snmpData1[oidifInOctets]);
Counter32 I2 = new Counter32();
I2.Set(snmpData2[oidifInOctets]);
Counter32 speed = new Counter32();
speed.Set(snmpDataS[oidifSpeed]);
if (I2.Value == I1.Value)
{
missed += 1;
continue;
}
decimal bandWithUsage = (((decimal)(I2.Value - I1.Value) * 8) * 100) / (speed * duration * (1 + missed));
Console.WriteLine("BandWith usage : {0}%", bandWithUsage);
missed = 0;
}
}
}
}

Answer 1

编译器建议，因为您显式指定字段类型而不是使用var snmpVerb = ...，所以不需要构造函数名称，而使用以下缩短的语法:

SimpleSnmp  snmpVerb = new ("192.168.1.121", 161, "public");

如果你右键单击SimnpleSnmp构造函数的调用并选择Quick Actions and Refactorings，它将为你提供一些建议，这是其中之一。

Answer 2

正如IDE0090文档所示，您可以使用c# 9目标类型的new表达式并简化实例创建。例如from:

SimpleSnmp snmpVerb = new SimpleSnmp("192.168.1.121", 161, "public");
Oid oidifSpeed = new Oid(".1.3.6.1.2.1.2.2.1.5.10");

:

SimpleSnmp snmpVerb = new("192.168.1.121", 161, "public");
Oid oidifSpeed = new(".1.3.6.1.2.1.2.2.1.5.10");

或者直接用var:

var snmpVerb = new SimpleSnmp("192.168.1.121", 161, "public");
var oidifSpeed = new Oid(".1.3.6.1.2.1.2.2.1.5.10");

请注意，这些不是错误，而是信息消息，它们不会影响程序的正确性/编译。