Nullable reference types are now enabled by default on projects created with Visual Studio 2022, so let’s have a quick look at them…<\/p>\n
Enabling nullable reference type checking<\/strong><\/p>\n By default nullable reference types were disabled prior to Visual Studio 2022, so would need enable them at a project or file level. Enabling in the project means adding the following to the .csproj file<\/p>\n If you prefer to enable at a file level then simply add the following to the top of each file<\/p>\n Now what?<\/strong><\/p>\n So once you’ve enabled nullable reference type checking, especially if on a legacy code base, be prepared for warnings such as <\/p>\n I’m sure there are plenty of other warnings, but you get the idea.<\/p>\n Basically what we’re ask the compiler to do is tell us when we might have the potential to be passing a null into a function etc. and highlight the potential issue with a warning. In other words we now need to mark reference types as nullable so the compiler knows we’re expecting a null and in situations where we’re not using a nullable reference type we’ll be warned.<\/p>\n Let’s see some example code. First off, if you default arguments to null, for example<\/p>\n This will result in the warning >warning CS8625: Cannot convert null literal to non-nullable reference type.<\/em>. All we need to do is tell the compiler we’re expecting a null, by making the argument nullable, i.e. add the ? to the type just like nullable value types.<\/p>\n Any usage of the variable name<\/em> will now expect a null check, so if we compile the following<\/p>\n as you’d imagine, the compiler will issue a warning here, in this case warning CS8602: Dereference of a possibly null reference.<\/em>, so obviously we have the potential of a null reference exception here, so adding a conditional check like this will fix that<\/p>\n In some situations you may in fact know a variable\/argument is not null – in TypeScript it’s not unusual to find the transpiler getting a little confused in which case we use the null-forgiving operator<\/em> simply an !, so whilst the SetName<\/em> method, as it stands ofcourse can be null, what if we remove the optional argument and expect all callers of the SetName<\/em> method – for example maybe it’s a private method and we know each caller must check for null first anyway, then we use the following<\/p>\n We’re basically saying, by using name!.<\/em> we know the value is not null. This example is a little contrived because we could just change the string?<\/em> to string<\/em> and not require the !, but you get the idea.<\/p>\n","protected":false},"excerpt":{"rendered":" Nullable reference types are now enabled by default on projects created with Visual Studio 2022, so let’s have a quick look at them… Enabling nullable reference type checking By default nullable reference types were disabled prior to Visual Studio 2022, so would need enable them at a project or file level. Enabling in the project […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[3],"tags":[],"class_list":["post-8841","post","type-post","status-publish","format-standard","hentry","category-c"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/posts\/8841","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/comments?post=8841"}],"version-history":[{"count":5,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/posts\/8841\/revisions"}],"predecessor-version":[{"id":9298,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/posts\/8841\/revisions\/9298"}],"wp:attachment":[{"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/media?parent=8841"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/categories?post=8841"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/tags?post=8841"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}\r\n<PropertyGroup>\r\n <OutputType>Exe<\/OutputType>\r\n <TargetFramework>net5.0<\/TargetFramework>\r\n <Nullable>enable<\/Nullable>\r\n<\/PropertyGroup>\r\n<\/pre>\n
\r\n#nullable enable\r\n<\/pre>\n
\n
\r\npublic void SetName(string name = null)\r\n{\r\n \/\/ do something\r\n}\r\n<\/pre>\n\r\npublic void SetName(string? name = null)\r\n{\r\n \/\/ do something\r\n}\r\n<\/pre>\n\r\npublic void SetName(string? name = null)\r\n{\r\n Console.WriteLine(name.Length);\r\n}\r\n<\/pre>\n\r\nstatic void SetName(string? name = null)\r\n{\r\n if (name != null)\r\n {\r\n Console.WriteLine(name.Length);\r\n }\r\n}\r\n<\/pre>\n\r\nstatic void SetName(string? name)\r\n{\r\n Console.WriteLine(name!.Length);\r\n}\r\n<\/pre>\n