D programming Language
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In, Out and InheritanceIf a function in a derived class overrides a function in its super class, then only one of the in contracts of the base functions must be satisified Overriding functions then becomes a process of loosening the in contracts. Conversely, all of the out contracts needs to be satisified, so overriding functions becomes a processes of tightening the out contracts. Class InvariantsClass invariants are used to specify characteristics of a class that always must be true (except while executing a member function). They are described in Classes. Debug and VersionD supports building multiple versions and various debug builds from the same source code using the features: DebugSpecification DebugAttribute DebugStatement VersionSpecification VersionAttribute VersionStatement Predefined VersionsSeveral environmental version identifiers and identifier name spaces are predefined to encourage consistent usage. Version identifiers do not conflict with other identifiers in the code, they are in a separate name space. DigitalMars Digital Mars is the compiler vendor X86 Intel and AMD 32 bit processors Win32 Microsoft 32 bit Windows systems linux All linux systems LittleEndian Byte order, least significant first BigEndian Byte order, most significant first D_InlineAsm Inline assembler is implemented none Never defined; used to just disable a section of code Others will be added as they make sense and new implementations appear. It is inevitable that the D language will evolve over time. Therefore, the version identifier namespace beginning with "D_" is reserved for identifiers indicating D language specification or new feature conformance. Compiler vendor specific versions can be predefined if the trademarked vendor identifier prefixes it, as in: version(DigitalMars_funky_extension) { ...
} It is important to use the right version identifier for the right purpose. For example, use the vendor identifier when using a vendor specific feature. Use the operating system identifier when using an operating system specific feature, etc. SpecificationDebugSpecification debug = Identifier ; debug = Integer ;
Version specifications do not declare any symbols, but instead set a version in the same manner that the -version does on the command line. The version specification is used for conditional compilation with version attributes and version statements. The version specification makes it straightforward to group a set of features under one major version, for example: version (ProfessionalEdition) { version = FeatureA; version = FeatureB; version = FeatureC; } version (HomeEdition) { version = FeatureA; } ...
version (FeatureB) { ... implement Feature B ... } Debug StatementTwo versions of programs are commonly built, a release build and a debug build. The debug build commonly includes extra error checking code, test harnesses, pretty-printing code, etc. The debug statement conditionally compiles in its statement body. It is D's way of what in C is done with #ifdef DEBUG / #endif pairs. DebugStatement: debug Statement debug ( Integer ) Statement debug ( Identifier ) Statement Debug statements are compiled in when the -debug switch is thrown on the compiler. debug(Integer) statements are compiled in when the debug level n set by the -debug(n) switch is <= Integer. debug(Identifier) statements are compiled in when the debug identifier set by the -debug(identifer) matches Identifier. If Statement is a block statement, it does not introduce a new scope. For example: int k; debug
{ int i; int k; // error, k already defined i = 3; } x = i; // uses the i declared above There is no else clause for a debug statement, as debug statements should add code, not subtract code. Version StatementIt is commonplace to conveniently support multiple versions of a module with a single source file. While the D way is to isolate all versioning into separate modules, that can get burdensome if it's just simple line change, or if the entire program would otherwise fit into one module. VersionStatement: VersionPredicate Statement VersionPredicate Statement else Statement VersionPredicate version ( Integer ) version ( Identifier ) The version statement conditionally compiles in its statement body based on the version specified by the Integer of Identifier. Both forms are set by the -version switch to the compiler. If Statement is a block statement, it does not introduce a new scope. For example: int k; version (Demo) // compile in this code block for the demo version { int i; int k; // error, k already defined i = 3; } x = i; // uses the i declared above The version statement works together with the version attribute for declarations. Version statements can nest. The optional else clause gets conditionally compiled in if the version predicate is false: version (X86) { ... // implement custom inline assembler version } else
{ ... // use default, but slow, version } While the debug and version statements superficially behave the same, they are intended for very different purposes. Debug statements are for adding debug code that is removed for the release version. Version statements are to aid in portability and multiple release versions. Directory: upload upload -> 587 Return function, r i(X) r i(0) r i(1) r i(2) r i(3) 1 0 2 4 6 Thermal Station, I 2 0 1 5 6 3 0 3 5 6 10 upload -> Department of science and humanities department of mathematics part-a questions and answers upload -> The Case Against the nypd’s Quota-Driven ‘Broken Windows’ Policing What Is It? upload -> For want of a nail upload -> Traditional British values upload -> Tv shows, Made for tv movies, Mini Series & Internet Programs Shot at Paramount Ranch upload -> Ownership Models There are two different types of ownership models upload -> Police Militarization upload -> City of rising star regular meting thursday, july 14, 2016 upload -> Township of winfield Download 1.66 Mb. Share with your friends:
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