我想更好地理解其中的区别。我在网上找到了很多解释,但它们都倾向于抽象的差异,而不是实际的含义。
Most of my programming experiences has been with CPython (dynamic, interpreted), and Java (static, compiled). However, I understand that there are other kinds of interpreted and compiled languages. Aside from the fact that executable files can be distributed from programs written in compiled languages, are there any advantages/disadvantages to each type? Oftentimes, I hear people arguing that interpreted languages can be used interactively, but I believe that compiled languages can have interactive implementations as well, correct?
编译器和解释器做同样的工作:将一种编程语言翻译成另一种编程语言,通常更接近硬件,通常是直接可执行的机器代码。
Traditionally, "compiled" means that this translation happens all in one go, is done by a developer, and the resulting executable is distributed to users. Pure example: C++.
Compilation usually takes pretty long and tries to do lots of expensive optmization so that the resulting executable runs faster. End users don't have the tools and knowledge to compile stuff themselves, and the executable often has to run on a variety of hardware, so you can't do many hardware-specific optimizations. During development, the separate compilation step means a longer feedback cycle.
Traditionally, "interpreted" means that the translation happens "on the fly", when the user wants to run the program. Pure example: vanilla PHP. A naive interpreter has to parse and translate every piece of code every time it runs, which makes it very slow. It can't do complex, costly optimizations because they'd take longer than the time saved in execution. But it can fully use the capabilities of the hardware it runs on. The lack of a separrate compilation step reduces feedback time during development.
But nowadays "compiled vs. interpreted" is not a black-or-white issue, there are shades in between. Naive, simple interpreters are pretty much extinct. Many languages use a two-step process where the high-level code is translated to a platform-independant bytecode (which is much faster to interpret). Then you have "just in time compilers" which compile code at most once per program run, sometimes cache results, and even intelligently decide to interpret code that's run rarely, and do powerful optimizations for code that runs a lot. During development, debuggers are capable of switching code inside a running program even for traditionally compiled languages.
首先,澄清一下,Java不是完全静态编译和以c++的方式链接的。它被编译成字节码,然后由JVM解释。JVM可以对本机机器语言进行即时编译,但不必这样做。
更重要的是:我认为交互性是主要的实际区别。由于所有内容都是解释的,所以您可以截取一小段代码,解析并根据环境的当前状态运行它。因此,如果您已经执行了初始化变量的代码,则可以访问该变量,等等。它真的很适合函数式风格。
然而,解释成本很高,特别是当您有一个包含大量引用和上下文的大型系统时。根据定义,这是一种浪费,因为相同的代码可能必须解释和优化两次(尽管大多数运行时都为此进行了缓存和优化)。不过,您仍然需要支付运行时成本,并且经常需要运行时环境。您也不太可能看到复杂的过程间优化,因为目前它们的性能还没有充分的交互性。
因此,对于不会有太大变化的大型系统,以及某些语言,更有意义的是预编译和预链接所有内容,做所有可以做的优化。最终会得到一个非常精简的运行时,该运行时已经针对目标机器进行了优化。
至于生成可执行文件,恕我直言,这一点关系不大。通常可以从编译语言创建可执行文件。但是您也可以使用解释语言创建可执行文件,只不过解释器和运行时已经打包在可执行文件中,并且对您隐藏了。这意味着您通常仍然需要支付运行时成本(尽管我确信对于某些语言,有方法将所有内容转换为可执行树)。
我不同意所有的语言都可以互动。某些语言,如C语言,与机器和整个链接结构紧密相连,我不确定您是否能够构建一个有意义的完整的交互式版本