{"id":2658,"date":"2022-01-09T15:37:53","date_gmt":"2022-01-09T10:07:53","guid":{"rendered":"https:\/\/www.rangakrish.com\/?p=2658"},"modified":"2022-01-09T15:37:53","modified_gmt":"2022-01-09T10:07:53","slug":"universal-function-call-syntax-ufcs-in-d-language","status":"publish","type":"post","link":"https:\/\/www.rangakrish.com\/index.php\/2022\/01\/09\/universal-function-call-syntax-ufcs-in-d-language\/","title":{"rendered":"Universal Function Call Syntax (UFCS) in D Language"},"content":{"rendered":"

One of the many “cool’<\/strong><\/em> features of Dlang<\/strong><\/em> is “Universal Funcion Call Syntax”<\/strong><\/em><\/a>, which permits non-member functions to be invoked using the member function call syntax. When you add to this the fact that this applies not just to user-defined types but to primitive types as well, things get interesting.\u00a0<\/span><\/p>\n

Let us look at some examples to understand this feature.\u00a0<\/span><\/p>\n

Here is our first example:<\/p>\n

\"Example-1\"<\/a>
Example 1<\/strong><\/figcaption><\/figure>\n

Here we have a user-defined type “A”<\/strong><\/em> with member function “foo()”<\/strong><\/em>. There is also a non-member function (“free”<\/strong><\/em> function) called “bar()”<\/strong><\/em> which takes “A”<\/strong><\/em> as its first argument. Line 28 shows how it is posible to call “bar()”<\/strong><\/em> as if it is a member function of “A”<\/strong><\/em>, in the same manner “foo()”<\/strong><\/em> is called. This is called UFCS<\/strong><\/em> in Dlang<\/strong><\/em>.<\/p>\n

What about the other way? Can member functions be invoked using regular function call syntax? No, that is not possible. See below:<\/p>\n

\"Example<\/a>
Example 2<\/strong><\/figcaption><\/figure>\n

Line 26 is OK, but not Line 32.\u00a0<\/span><\/p>\n

Another case to consider is having a non-member function with the same name as member function and with the first argument as the user-defined type.\u00a0<\/span><\/p>\n

Take a look at this example:<\/p>\n

\"Example<\/a>
Example 3<\/strong><\/figcaption><\/figure>\n

Here, in addition to the member function “foo()”<\/strong><\/em> in “<\/strong>A”<\/strong><\/em>, we also have a non-member function “foo()”<\/strong><\/em> taking “A”<\/strong><\/em> type as its only argument. In this case, how does UFCS<\/strong><\/em> work? Line 33 shows that the member function will be used even if the “signature”<\/strong><\/em> appears to be the same. This means UFCS<\/strong><\/em> comes into picture only when there is no member function with that name.<\/p>\n

An additional rule is that functions declared in local scope (“nested”<\/strong><\/em> functions) are not considered for UFCS<\/strong><\/em>. This is shown in the following example:<\/p>\n

\"Example<\/a>
Example 4<\/strong><\/figcaption><\/figure>\n

Line 44 shows that the nested function cannot take advantage of UFCS<\/strong><\/em> feature.<\/p>\n

Finally, it is worthwhile to point out that even primitive<\/strong><\/em> types in DLang<\/strong><\/em> can take advantage of UFCS<\/strong><\/em>. Here is how:<\/p>\n

\"Example<\/a>
Example 5<\/strong><\/figcaption><\/figure>\n

The above shows how a sequence of operations on an integer array can be elegantly expressed using “chaining”<\/strong><\/em>, thanks to UFCS<\/strong><\/em>!<\/p>\n

Have a great weekend!<\/p>\n","protected":false},"excerpt":{"rendered":"

One of the many “cool’ features of Dlang is “Universal Funcion Call Syntax”, which permits non-member functions to be invoked using the member function call syntax. When you add to this the fact that this applies not just to user-defined types but to primitive types as well, things get interesting.\u00a0 Let us look at some […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"advanced_seo_description":"","jetpack_seo_html_title":"","jetpack_seo_noindex":false,"jetpack_seo_schema_type":"","_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[302,17],"tags":[305,306],"class_list":["post-2658","post","type-post","status-publish","format-standard","hentry","category-d-language","category-programming","tag-dlang","tag-ufcs"],"jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p9OLnF-GS","jetpack-related-posts":[{"id":1091,"url":"https:\/\/www.rangakrish.com\/index.php\/2018\/10\/14\/c17-stdapply-and-stdinvoke\/","url_meta":{"origin":2658,"position":0},"title":"C++17 – std::apply() and std::invoke()","author":"admin","date":"October 14, 2018","format":false,"excerpt":"Calling a function (or function object) dynamically, through a pointer known at runtime, is a common programming scenario. 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With funcall,\u2026","rel":"","context":"In "C++"","block_context":{"text":"C++","link":"https:\/\/www.rangakrish.com\/index.php\/category\/c\/"},"img":{"alt_text":"Calling Member Functions","src":"https:\/\/i0.wp.com\/www.rangakrish.com\/wp-content\/uploads\/2018\/10\/Code5.png?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.rangakrish.com\/wp-content\/uploads\/2018\/10\/Code5.png?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.rangakrish.com\/wp-content\/uploads\/2018\/10\/Code5.png?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/www.rangakrish.com\/wp-content\/uploads\/2018\/10\/Code5.png?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":2152,"url":"https:\/\/www.rangakrish.com\/index.php\/2020\/09\/28\/template-based-text-generation\/","url_meta":{"origin":2658,"position":1},"title":"Template-Based Text Generation","author":"admin","date":"September 28, 2020","format":false,"excerpt":"I had written earlier about natural language generation\u00a0using my iLangGen framework. 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