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The use of templates as a metaprogramming technique requires two distinct operations: a template must be defined, and a defined template must be instantiated.The generic form of the generated source code is described in the template definition, and when the template is instantiated, the generic form in the template is used to generate a specific set of source code.
Polymorphic algorithms make it difficult for such software to recognize the offending code because it constantly mutates. Malicious programmers have sought to protect their encrypted code from this virus-scanning strategy by rewriting the unencrypted decryption engine (and the resulting encrypted payload) each time the virus or worm is propagated.
(In a dynamic code generator, this call is a direct call as the direct address is back patched by cache miss logic.) Prologue code in the called method then compares the cached class with the actual object class, and if they don't match, execution branches to a cache miss handler to find the correct method in the class.
Monomorphization is a compile-time process where polymorphic functions are replaced by many monomorphic functions for each unique instantiation. [1] It is considered beneficial to undergo the mentioned transformation because it results in the output intermediate representation (IR) having specific types, which allows for more effective optimization.
A polymorphic engine (sometimes called mutation engine or mutating engine) is a software component that uses polymorphic code to alter the payload while preserving the same functionality. Polymorphic engines are used almost exclusively in malware , with the purpose of being harder for antivirus software to detect.
This enables dynamic (run-time) polymorphism, where the referred objects can behave differently, depending on their (actual, derived) types. C++ also provides the dynamic_cast operator, which allows code to safely attempt conversion of an object, via a base reference/pointer, to a more derived type: downcasting.
Metamorphic code is used by some viruses when they are about to infect new files, and the result is that the next generation will never look like current generation. The mutated code will do exactly the same thing (under the interpretation used), but the child's binary representation will typically be completely different from the parent's.
Several code generation DSLs (attribute grammars, tree patterns, source-to-source rewrites) Active DSLs represented as abstract syntax trees DSL instance Well-formed output language code fragments Any programming language (proven for C, C++, Java, C#, PHP, COBOL) gSOAP: C / C++ WSDL specifications