TL:DR: a slice compare is some Python overhead + a highly-optimized memcmp (unless there’s UTF-8 processing?). Ideally, use slice compares to find the first mismatch to within less than 128 bytes or something, then loop a char at a time. Or if it’s an option and the problem is important, make a modified copy of … Read more
The fundamental trick is to recognize that parsing, however accomplished, happens in incremental steps, including the reading of the tokens one by one. At each incremental step, there is an opportunity to build part of the AST by combining AST fragments built by other incremental steps. This is a recursive idea, and it bottoms out … Read more
Sure, just open a new figure: import matplotlib.pyplot as plt plt.plot(range(10)) plt.figure() plt.plot(range(10), ‘ro-‘) plt.figure(), plt.plot(…) plt.show() # only do this once, at the end If you’re running this in the default python interpreter, this won’t work, as each figure needs to enter the gui’s mainloop. If you want to run things in an interactive … Read more
The bytecode is not actually interpreted to machine code, unless you are using some exotic implementation such as pypy. Other than that, you have the description correct. The bytecode is loaded into the Python runtime and interpreted by a virtual machine, which is a piece of code that reads each instruction in the bytecode and … Read more
php.ini is read when the PHP module is loaded in both mod_php, FastCGI and FPM. In regular CGI mode, the config file have to be read at runtime because there’s no preforked processes of any kind. I think the only real advantage of running PHP as a module inside the web server is that the … Read more
The name of the interpreter is stored in the variable sys.executable
The issue is not EOF but EOL. The shell sees a ^M as well as the end of line and thus tries to find /usr/bin/python^M . The usual way of getting into this state is to edit the python file with a MSDOS/Windows editor and then run on Unix. The simplest fix is to run … Read more
Compiler – compiles code to a lower level code. Example: “Developer code” -> “Machine code” PHP -> C Java -> bytecode Transpiler – compiles code to same level of code/abstraction. Example: “Developer code” -> “Another developer code or version” JavaScript ES2015+ -> JavaScript ES5 Interpreter – interprets code, not really in the same class/league/context with … Read more
I have implemented several parsers in C# – hand-written and tool generated. A very good introductory tutorial on parsing in general is Let’s Build a Compiler – it demonstrates how to build a recursive descent parser; and the concepts are easily translated from his language (I think it was Pascal) to C# for any competent … Read more
The Python interpreter assigns the last expression value to _. This behaviour is limited to the REPL interpreter only, and is intended to assist in interactive coding sessions: >>> import math >>> math.pow(3.0, 5) 243.0 >>> result = _ >>> result 243.0 The standard Python interpreter goes to some length to not trample on user-defined … Read more