{"id":4099,"date":"2023-02-08T19:36:39","date_gmt":"2023-02-08T18:36:39","guid":{"rendered":"https:\/\/gdksoftware.com\/knowledgebase\/unit-specific-typing-in-delphi"},"modified":"2023-03-22T13:11:46","modified_gmt":"2023-03-22T12:11:46","slug":"unit-digitacao-especifica-em-delphi","status":"publish","type":"knowledge","link":"https:\/\/gdksoftware.com\/pt-br\/base-de-conhecimento\/unit-digitacao-especifica-em-delphi","title":{"rendered":"“Unit” Digita\u00e7\u00e3o espec\u00edfica em Delphi"},"content":{"rendered":"

Os tipos primitivos t\u00eam regras de convers\u00e3o padr\u00e3o, muitas linguagens de programa\u00e7\u00e3o funcionam dessa forma por padr\u00e3o. Isto \u00e9 para que voc\u00ea n\u00e3o tenha que digitar tudo e \u00e9 realmente uma conveni\u00eancia. Por exemplo, voc\u00ea ser\u00e1 capaz de atribuir um Integer a um Extended sem problemas, tanto passando um 42 literal como atribuindo uma vari\u00e1vel do tipo Integer.<\/p>\n

\n
procedure<\/span> Hello<\/span>;<\/span>\r\nvar<\/span>\r\n  SomeNumber:<\/span> Extended<\/span>;<\/span>\r\n  AnotherNumber:<\/span> Integer<\/span>;<\/span>\r\nbegin<\/span>\r\n  AnotherNumber :=<\/span> 6<\/span>;<\/span>\r\n  SomeNumber :=<\/span> 2<\/span>;<\/span> \/\/ works<\/span>\r\n  SomeNumber :=<\/span> AnotherNumber;<\/span> \/\/ works<\/span>\r\nend<\/span>;<\/span>\r\n<\/pre>\n<\/div>\n
Mesmo que digitem aliasing, os tipos ainda s\u00e3o os tipos que eram e t\u00eam regras de convers\u00e3o autom\u00e1tica:<\/p>\n
\n
type<\/span>\r\n  ANewType =<\/span> Extended<\/span>;<\/span>\r\n  AnotherNewType =<\/span> Integer<\/span>;<\/span>\r\n\r\nimplementation<\/span>\r\n\r\nprocedure<\/span> Hello<\/span>;<\/span>\r\nvar<\/span>\r\n  SomeNumber:<\/span> ANewType;<\/span>\r\n  AnotherNumber:<\/span> AnotherNewType;<\/span>\r\nbegin<\/span>\r\n  AnotherNumber :=<\/span> 6<\/span>;<\/span>\r\n  SomeNumber :=<\/span> 2<\/span>;<\/span> \/\/ works<\/span>\r\n  SomeNumber :=<\/span> AnotherNumber;<\/span> \/\/ works<\/span>\r\nend<\/span>;<\/span>\r\n<\/pre>\n<\/div>\n
Se voc\u00ea realmente quer regras de convers\u00e3o rigorosas, porque, por exemplo, voc\u00ea quer evitar que os medidores sejam atribu\u00eddos a segundos ou vice-versa, voc\u00ea precisar\u00e1 criar novos tipos. E novos tipos s\u00e3o criados usando ou um registro ou uma classe.<\/p>\n
Para permitir certas convers\u00f5es, voc\u00ea pode adicionar essas regras aos tipos utilizando a sobrecarga do operador. (veja https:\/\/docwiki.embarcadero.com\/RADStudio\/Sydney\/en\/Operator_Overloading_(Delphi))<\/p>\n
No FPC a sintaxe \u00e9 diferente, mas voc\u00ea pode fazer o mesmo https:\/\/www.freepascal.org\/docs-html\/ref\/refse104.html#x224-24800015.3<\/p>\n
Voc\u00ea pode at\u00e9 mesmo fazer regras de convers\u00e3o para metros * segundos criando um tipo de metro por segundo.<\/p>\n
Aqui est\u00e1 um exemplo de como funciona em Delphi:<\/p>\n
 <\/p>\n
type<\/span>\r\n  metersPerSecond =<\/span> record<\/span>\r\n  private<\/span>\r\n    m:<\/span> Extended<\/span>;<\/span>\r\n    s:<\/span> Extended<\/span>;<\/span>\r\n\u00a0\r\n    value:<\/span> extended<\/span>;<\/span>\r\n\u00a0\r\n    mset:<\/span> Boolean<\/span>;<\/span>\r\n    sset:<\/span> Boolean<\/span>;<\/span>\r\n\u00a0\r\n    function<\/span> Units:<\/span> string<\/span>;<\/span>\r\n  public<\/span>\r\n    function<\/span> ToString:<\/span> string<\/span>;<\/span>\r\n  end<\/span>;<\/span>\r\n\u00a0\r\n  meters =<\/span> record<\/span>\r\n  private<\/span>\r\n    value:<\/span> Extended<\/span>;<\/span>\r\n\u00a0\r\n    function<\/span> Units:<\/span> string<\/span>;<\/span>\r\n  public<\/span>\r\n    class<\/span> operator Implicit(<\/span>Value:<\/span> Extended<\/span>)<\/span>:<\/span> meters;<\/span>\r\n    class<\/span> operator Explicit(<\/span>Value:<\/span> meters)<\/span>:<\/span> metersPerSecond;<\/span>\r\n    class<\/span> operator Multiply(<\/span>ms:<\/span> metersPerSecond;<\/span> m:<\/span> meters)<\/span>:<\/span> metersPerSecond;<\/span>\r\n\u00a0\r\n    function<\/span> ToString:<\/span> string<\/span>;<\/span>\r\n  end<\/span>;<\/span>\r\n\u00a0\r\n  seconds =<\/span> record<\/span>\r\n  private<\/span>\r\n    value:<\/span> Extended<\/span>;<\/span>\r\n\u00a0\r\n    function<\/span> Units:<\/span> string<\/span>;<\/span>\r\n  public<\/span>\r\n    class<\/span> operator Implicit(<\/span>Value:<\/span> Extended<\/span>)<\/span>:<\/span> seconds;<\/span>\r\n    class<\/span> operator Explicit(<\/span>Value:<\/span> seconds)<\/span>:<\/span> metersPerSecond;<\/span>\r\n    class<\/span> operator Multiply(<\/span>ms:<\/span> metersPerSecond;<\/span> s:<\/span> seconds)<\/span>:<\/span> metersPerSecond;<\/span>\r\n\u00a0\r\n    function<\/span> ToString:<\/span> string<\/span>;<\/span>\r\n  end<\/span>;<\/span>\r\n\u00a0\r\nimplementation<\/span>\r\n\u00a0\r\nuses<\/span>\r\n  SysUtils;<\/span>\r\n\u00a0\r\nclass<\/span> operator meters.<\/span>Implicit<\/span>(<\/span>Value:<\/span> Extended<\/span>)<\/span>:<\/span> meters;<\/span>\r\nbegin<\/span>\r\n  Result.<\/span>value<\/span> :<\/span>=<\/span> Value;<\/span>\r\nend<\/span>;<\/span>\r\n\u00a0\r\nclass<\/span> operator seconds.<\/span>Implicit<\/span>(<\/span>Value:<\/span> Extended<\/span>)<\/span>:<\/span> seconds;<\/span>\r\nbegin<\/span>\r\n  Result.<\/span>value<\/span> :<\/span>=<\/span> Value;<\/span>\r\nend<\/span>;<\/span>\r\n\u00a0\r\nclass<\/span> operator meters.<\/span>Explicit<\/span>(<\/span>Value:<\/span> meters)<\/span>:<\/span> metersPerSecond;<\/span>\r\nbegin<\/span>\r\n  Result.<\/span>m<\/span> :<\/span>=<\/span> Value.<\/span>value<\/span>;<\/span>\r\n  Result.<\/span>mset<\/span> :<\/span>=<\/span> True<\/span>;<\/span>\r\n  if<\/span> Result.<\/span>sset<\/span> then<\/span>\r\n    Result.<\/span>value<\/span> :<\/span>=<\/span> Result.<\/span>s<\/span> *<\/span> Result.<\/span>m<\/span>;<\/span> \r\nend<\/span>;<\/span>\r\n\u00a0\r\nclass<\/span> operator seconds.<\/span>Explicit<\/span>(<\/span>Value:<\/span> seconds)<\/span>:<\/span> metersPerSecond;<\/span>\r\nbegin<\/span>\r\n  Result.<\/span>s<\/span> :<\/span>=<\/span> Value.<\/span>value<\/span>;<\/span>\r\n  Result.<\/span>sset<\/span> :<\/span>=<\/span> True<\/span>;<\/span>\r\n  if<\/span> Result.<\/span>mset<\/span> then<\/span>\r\n    Result.<\/span>value<\/span> :<\/span>=<\/span> Result.<\/span>s<\/span> *<\/span> Result.<\/span>m<\/span>;<\/span> \r\nend<\/span>;<\/span>\r\n\u00a0\r\nclass<\/span> operator seconds.<\/span>Multiply<\/span>(<\/span>ms:<\/span> metersPerSecond;<\/span> s:<\/span> seconds)<\/span>:<\/span> metersPerSecond;<\/span>\r\nbegin<\/span>\r\n  Result :<\/span>=<\/span> ms;<\/span>\r\n  Result.<\/span>s<\/span> :<\/span>=<\/span> s.<\/span>value<\/span>;<\/span>\r\n  Result.<\/span>sset<\/span> :<\/span>=<\/span> True<\/span>;<\/span>\r\n  if<\/span> Result.<\/span>mset<\/span> then<\/span>\r\n    Result.<\/span>value<\/span> :<\/span>=<\/span> Result.<\/span>s<\/span> *<\/span> Result.<\/span>m<\/span>;<\/span> \r\nend<\/span>;<\/span>\r\n\u00a0\r\nclass<\/span> operator meters.<\/span>Multiply<\/span>(<\/span>ms:<\/span> metersPerSecond;<\/span> m:<\/span> meters)<\/span>:<\/span> metersPerSecond;<\/span>\r\nbegin<\/span>\r\n  Result :<\/span>=<\/span> ms;<\/span>\r\n  Result.<\/span>m<\/span> :<\/span>=<\/span> m.<\/span>value<\/span>;<\/span>\r\n  Result.<\/span>mset<\/span> :<\/span>=<\/span> True<\/span>;<\/span>\r\n  if<\/span> Result.<\/span>sset<\/span> then<\/span>\r\n    Result.<\/span>value<\/span> :<\/span>=<\/span> Result.<\/span>s<\/span> *<\/span> Result.<\/span>m<\/span>;<\/span> \r\nend<\/span>;<\/span>\r\n\u00a0\r\nfunction<\/span> metersPerSecond.<\/span>Units<\/span>:<\/span> string<\/span>;<\/span>\r\nbegin<\/span>\r\n  Result :<\/span>=<\/span> 'm\/s'<\/span>;<\/span>\r\nend<\/span>;<\/span>\r\n\u00a0\r\nfunction<\/span> metersPerSecond.<\/span>ToString<\/span>:<\/span> string<\/span>;<\/span>\r\nbegin<\/span>\r\n  Assert<\/span>(<\/span>mset and<\/span> sset)<\/span>;<\/span>\r\n\u00a0\r\n  Result :<\/span>=<\/span> Format<\/span>(<\/span>'%f%s'<\/span>,<\/span> [<\/span>value,<\/span> Units]<\/span>)<\/span>\r\nend<\/span>;<\/span>\r\n\u00a0\r\nfunction<\/span> meters.<\/span>Units<\/span>:<\/span> string<\/span>;<\/span>\r\nbegin<\/span>\r\n  Result :<\/span>=<\/span> 'm'<\/span>;<\/span>\r\nend<\/span>;<\/span>\r\n\u00a0\r\nfunction<\/span> meters.<\/span>ToString<\/span>:<\/span> string<\/span>;<\/span>\r\nbegin<\/span>\r\n  Result :<\/span>=<\/span> Format<\/span>(<\/span>'%f%s'<\/span>,<\/span> [<\/span>value,<\/span> Units]<\/span>)<\/span>;<\/span>\r\nend<\/span>;<\/span>\r\n\u00a0\r\nfunction<\/span> seconds.<\/span>Units<\/span>:<\/span> string<\/span>;<\/span>\r\nbegin<\/span>\r\n  Result :<\/span>=<\/span> 's'<\/span>;<\/span>\r\nend<\/span>;<\/span>\r\n\u00a0\r\nfunction<\/span> seconds.<\/span>ToString<\/span>:<\/span> string<\/span>;<\/span>\r\nbegin<\/span>\r\n  Result :<\/span>=<\/span> Format<\/span>(<\/span>'%f%s'<\/span>,<\/span> [<\/span>value,<\/span> Units]<\/span>)<\/span>;<\/span>\r\nend<\/span>;<\/span>\r\n\u00a0\r\nvar<\/span>\r\n  time:<\/span> seconds;<\/span>\r\n  distance:<\/span> meters;<\/span>\r\n  speed:<\/span> metersPerSecond;<\/span>\r\n  different_speed:<\/span> metersPerSecond;<\/span>\r\ninitialization<\/span>\r\n  time :<\/span>=<\/span> 10.0<\/span>;<\/span>\r\n  distance :<\/span>=<\/span> 3<\/span>;<\/span>\r\n\u00a0\r\n  \/\/ distance := meters; \/\/ does not work, because seconds are not meters!<\/span>\r\n\u00a0\r\n  speed :<\/span>=<\/span> metersPerSecond(<\/span>time)<\/span> *<\/span> distance;<\/span>\r\n\u00a0\r\n  \/\/ or the other way around<\/span>\r\n  speed :<\/span>=<\/span> metersPerSecond(<\/span>distance)<\/span> *<\/span> time;<\/span>\r\n\u00a0\r\n  WriteLn<\/span>(<\/span>'speed -> '<\/span> +<\/span> time.<\/span>ToString<\/span> +<\/span> ' * '<\/span> +<\/span> distance.<\/span>ToString<\/span> +<\/span> ' = '<\/span> +<\/span> Speed.<\/span>ToString<\/span>)<\/span>;<\/span>\r\n\u00a0\r\n  \/\/ different_speed := distance; \/\/ this doesn't work without explicit conversion<\/span>\r\n\u00a0\r\n  WriteLn<\/span>(<\/span>'different_speed -> '<\/span> +<\/span> different_speed.<\/span>ToString<\/span>)<\/span>;<\/span>\r\nend<\/span>.<\/span><\/pre>\n","protected":false},"featured_media":0,"parent":0,"template":"","class_list":["post-4099","knowledge","type-knowledge","status-publish","hentry","knowledge-category-arquivo-delphi"],"acf":{"author":1545,"type_hero":"compact","hero_image":2063,"hero_image_position":"","hero_title":"\"Unit\" Digita\u00e7\u00e3o espec\u00edfica em Delphi","hero_content":"","hero_link":null,"hero_show_h1":false},"yoast_head":"\n"Unit" Digita\u00e7\u00e3o espec\u00edfica em 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