为什么python在解释之前将源代码编译为字节码?
问题描述
为什么python在解释之前要把源码编译成字节码?
Why python compile the source to bytecode before interpreting?
为什么不直接从源头解释?
Why not interpret from the source directly?
解决方案
几乎没有解释器真正直接逐行解释代码——这实在是太低效了.几乎所有解释器都使用一些可以轻松执行的中间表示.此外，还可以对此中间代码进行小幅优化.
Nearly no interpreter really interprets code directly, line by line – it's simply too inefficient. Almost all interpreters use some intermediate representation which can be executed easily. Also, small optimizations can be performed on this intermediate code.
Python 还存储了这段代码，这对下次执行这段代码有很大的好处:Python 不再需要解析代码；解析是编译过程中最慢的部分.因此，字节码表示可以大大减少执行开销.
Python furthermore stores this code which has a huge advantage for the next time this code gets executed: Python doesn't have to parse the code anymore; parsing is the slowest part in the compile process. Thus, a bytecode representation reduces execution overhead quite substantially.
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