I always thought it was a compiled language. I'm curious where the confusion comes from Mako: Please explain where you saw that objective-C was interpreted. Please provide the quote or the link that confused you. Languages are specifications , often in some document written in English but some languages have formalized their semantics in more mathematical notations.
Being interpreted or compiled is a property of implementations , not of languages. Add a comment. Active Oldest Votes. Improve this answer. Part of the question the OP is asking stems from the fact that Objective-C was originally run through a pre-processor and not directly run through an interpreted or a compiler which generated C code. This could then be either run through a compiler that generates native machine code, or interpreted in some form aside: I built a C interpreter once, just for fun.
For simplicities sake people do say "C is a compiled language" - which - though wrong - actually denotes that C usually runs through a compiler. So while C can obviously be interpreted, I think it is safe to say that the rationale behind the language is to allow for efficient compilation, yielding a run-time performance close to what you can obtain with assembler.
Hence, interpreting C is possible and even useful in some situations , but it is counter to the original intentions of the language's designers. This, interestingly, results in better performance than using compiled C extensions from YARV the "standard" Ruby implementation. The Objective-C language defers as many decisions as it can from compile time and link time to runtime.
Whenever possible, it does things dynamically. This means that the language requires not just a compiler, but also a runtime system to execute the compiled code. Show 1 more comment.
From Wikipedia : Some language specifications spell out that implementations must include a compilation facility; for example, Common Lisp.
Basically the program is of 3 sections:. And if you are not familiar with the interface based program and if ObjC is going to be the 1st programming language learning interface-based programming , then I strongly recommend to gain some basic knowledge of what does interfaces means and how they are used and useful to the software construction.
Every class you wanted to create i. Thats why you create interface. So, it is two piece of work you have to do. And remember that, when you are modelling your classes, it always becomes your interface class not implementation class. The interface should extend a class which is of type Object or it should be from the family of the type Object to provide the basic operations like new, free, alloc etc. The implementation class is going to hold the logic what needs to be performed when a defined message by interface is sent to the object.
In this case when a hello message is sent to the object, the implementation defines what needs to be done. Though you write the program in a C like language, do not think procedurally. You might want to write comparitively more number of lines than you think. First some general theory. Anyway you need to do the same set of actions to make the app package which can be installed on a device.
Code compilation is one of the steps you need to do together with linking, bundling the resources, code signing and so on. The frontend takes our source code and converts it into some intermediate language understandable for the backend. The backend takes this intermediate representation and turns it into machine code with the regard of the specific operation system and processor architecture.
The Core just takes this representation works with it and generates an executable or dynamic library. Here is an example of AST:. As you could already see LLVM Core is the place where the code is optimized, and Intermediate Representation is specifically the source of these optimizations.
The official list of LLVM passes without separation to different levels can be found here. When creating a new project Xcode sets up 2 configurations with following default values for the LLVM optimization levels:. Interestingly enough, configuration option responsible for C-family language optimisation calls in project. If you dive a bit in the history of Xcode you will see that till Xcode 3 the GCC GNU Compiler Collection was the compiler used by the IDE, then there was a transition period when the user could change the compiler in the target settings and with the release of Xcode 5 CLang became the only option a piece of such history.
Seems like the target property name still has that legacy. Swift is young and rapidly developing language. In terms of code optimisation some features are being changed and new features appear almost every year. You can see lots of similarities with the one for ObjC: not only the same backend but also the frontend essentially works similarly.
Lexical analysis, tokenization separating some lexical items from the raw string , building AST, type checking. So SIL was the solution for this problem. At different steps the parts of the Swift compiler produce different kinds of SIL. Raw SIL is just another representation of your code: no diagnostics, no changes, potential data flow errors.
A small set of optimisations is being made on the raw SIL even if you have all the optimizations switched off - Guaranteed Optimization Passes and Diagnostic Passes :. Canonical SIL means that guaranteed optimizations and diagnostics were done, so all the data flow errors should be eliminated and certain instructions must be canonicalized to simpler forms.
And here is the turn for General Optimization Passes , which are done or not done according to the optimization level you set up:. Until Swift 4. But now there are already 3 different levels:.
0コメント