These tricks may be obvious, but at least I’m going to write them down.<\/p>\n
It is common to import an entire namespace into the global namespace. I’m not saying it’s a good idea<\/a>, but it is common. The most notorious example is to put<\/p>\n to import the When working with the Windows Runtime, you often have rather deep namespaces. For example, we saw some time ago that we were operating in the in your program just to save yourself the hassle of typing it all out.<\/p>\n However, things get complicated if you create name collisions.<\/p>\n For example, if you are using WRL, you will be working with the you now have a problem because you have imported the name After these two declarations, the name I’ve worked around this by using namespace aliases:<\/p>\n This lets me use However, this gets clunky once you have multiple namespaces you want to access:<\/p>\n because you have to juggle all these aliases. <\/`P><\/p>\n But there’s a more attractive solution: Move names around by importing them into another namespace. (The name for this technique is “namespace composition”, covered in sections 14.4.3 and 14.4.4<\/a> of The C++ Programming Language<\/i><\/a>.)<\/p>\n The first block of Similarly for the other two blocks.<\/p>\n The upshot of this is that you can now do this<\/p>\n In particular, this trick works with Windows Runtime classes because as a general rule, Windows Runtime type names are unique across all Windows Runtime namespaces, so you won’t inadvertently introduce a name collision by The general rule makes Windows Runtime types easier to search for (both on the Web and in your code) because you will have fewer false positives.<\/p>\n Bonus chatter<\/b>: The exception to the general rule is DirectX. Windows Runtime naming conventions permit the same name to be used in different versions of DirectX. This isn’t a problem because in practice, each application picks one version of DirectX and sticks with it; applications don’t try to mix-and-match different versions of DirectX.<\/p>\n Bonus bonus chatter<\/b>: The above rule is on the books, but has yet to be exercised. As of this writing, the only version of DirectX in the Windows Runtime is DirectX11.<\/p>\n","protected":false},"excerpt":{"rendered":" Shuffling names around.<\/p>\n","protected":false},"author":1069,"featured_media":111744,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[25],"class_list":["post-98765","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-code"],"acf":[],"blog_post_summary":" Shuffling names around.<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/98765","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/users\/1069"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/comments?post=98765"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/98765\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media\/111744"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media?parent=98765"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=98765"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=98765"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}using namespace std;\r\n<\/pre>\n
std<\/code> namespace into the global namespace.<\/p>\nWindows::using namespace Windows::System::Profile::SystemManufacturers;\r\n<\/pre>\n
ABI::using namespace ABI::Windows::System::Profile::SystemManufacturers;\r\n<\/pre>\n
Smbios\u00adInformation<\/code> twice:<\/p>\nusing namespace Windows::System::Profile::SystemManufacturers;\r\nusing namespace ABI::Windows::System::Profile::SystemManufacturers;\r\n<\/pre>\n
System\u00adInformation<\/code> is now ambiguous. It could refer to Windows::using<\/code> declaration, or it oculd refer to ABI::System\u00adInformation<\/code>, via the second using<\/code> declaration. <\/code><\/p>\nnamespace wspsm = Windows::System::Profile::SystemManufacturers;\r\nnamespace awspsm = ABI::Windows::System::Profile::SystemManufacturers;\r\n<\/pre>\n
wspsm::Smbios\u00adInformation<\/code> and awspsm::Smbios\u00adInformation<\/code> to refer to the C++\/CX or ABI versions, respectively.<\/p>\nnamespace wspsm = Windows::System::Profile::SystemManufacturers;\r\nnamespace awspsm = ABI::Windows::System::Profile::SystemManufacturers;\r\nnamespace wwspsm = winrt::Windows::System::Profile::SystemManufacturers;\r\n\r\nnamespace wuvm = Windows::UI::ViewManagement;\r\nnamespace awuvm = ABI::Windows::UI::ViewManagement;\r\nnamespace wwuvm = winrt::Windows::UI::ViewManagement;\r\n\r\nnamespace wsc = Windows::Security::Cryptography;\r\nnamespace awsc = ABI::Windows::Security::Cryptography;\r\nnamespace wwsc = winrt::Windows::Security::Cryptography;\r\n<\/pre>\n
namespace ABI\r\n{\r\n using Windows::System::Profile::SystemManufacturers;\r\n using Windows::UI::ViewManagement;\r\n using Windows::Security::Cryptography;\r\n}\r\n\r\nnamespace cx\r\n{\r\n using Windows::System::Profile::SystemManufacturers;\r\n using Windows::UI::ViewManagement;\r\n using Windows::Security::Cryptography;\r\n}\r\n\r\nnamespace winrt\r\n{\r\n using Windows::System::Profile::SystemManufacturers;\r\n using Windows::UI::ViewManagement;\r\n using Windows::Security::Cryptography;\r\n}\r\n<\/pre>\nusing<\/code> declarations imports the contents of the ABI::ABI::ABI::ABI<\/code> namespace.<\/p>\n\n\n
\n Old and busted<\/th>\n To get<\/th>\n<\/tr>\n \n New hotness<\/th>\n<\/tr>\n \n awspsm::\n ABI::System\u00adManufacturers::SmbiosInformation<\/code><\/div>\n<\/td>\n<\/tr>\n\n \u00a0\u00a0\u00a0ABI::\n \u00a0wspsm::\n Windows::System\u00adManufacturers::SmbiosInformation<\/code><\/div>\n<\/td>\n<\/tr>\n\n \u00a0\u00a0\u00a0\u00a0cx::\n wwspsm::\n winrt::System\u00adManufacturers::SmbiosInformation<\/code><\/div>\n<\/td>\n<\/tr>\n\n \u00a0winrt::\n \u00a0awuvm::\n ABI::Application\u00adView<\/code><\/div>\n<\/td>\n<\/tr>\n\n \u00a0\u00a0\u00a0ABI::\n \u00a0\u00a0wuvm::\n Windows::Application\u00adView<\/code><\/div>\n<\/td>\n<\/tr>\n\n \u00a0\u00a0\u00a0\u00a0cx::\n \u00a0wwuvm::\n winrt::Application\u00adView<\/code><\/div>\n<\/td>\n<\/tr>\n\n \u00a0winrt::\n \u00a0\u00a0awsc::\n ABI::Cryptographic\u00adBuffer<\/code><\/div>\n<\/td>\n<\/tr>\n\n \u00a0\u00a0\u00a0ABI::\n \u00a0\u00a0\u00a0wsc::\n Windows::Cryptographic\u00adBuffer<\/code><\/div>\n<\/td>\n<\/tr>\n\n \u00a0\u00a0\u00a0\u00a0cx::\n \u00a0\u00a0wwsc::\n winrt::Cryptographic\u00adBuffer<\/code><\/div>\n<\/td>\n<\/tr>\n\n \u00a0winrt::using<\/code> a bunch of Windows Runtime namespaces together.<\/p>\n