It is not that commonly used. It is used when you have Python source code in string form, and you want to make it into a Python code object that you can keep and use. Here’s a trivial example: >>> codeobj = compile(‘x = 2\nprint “X is”, x’, ‘fakemodule’, ‘exec’) >>> exec(codeobj) X is 2 … Read more
Just delete the name that is masking the builtin: >>> set=”oops” >>> set ‘oops’ >>> del set >>> set <type ‘set’> You can always still access the original built-in through the builtins module (__builtin__ on Python 2, with underscores and no s); use this if you want to override the built-in but want to defer … Read more
<() is called process substitution in the manual, and is similar to a pipe but passes an argument of the form /dev/fd/63 instead of using stdin. < reads the input from a file named on command line. Together, these two operators function exactly like a pipe, so it could be rewritten as find /bar -name … Read more
If obj is a dictionary, use its update function: obj.update(add_obj)
The read in your script command is fine. However, you execute it in the pipeline, which means it is in a subshell, therefore, the variables it reads to are not visible in the parent shell. You can either move the rest of the script in the subshell, too: echo hello | { read str echo … Read more
Python tries to discourage you from “summing” strings. You’re supposed to join them: “”.join(list_of_strings) It’s a lot faster, and uses much less memory. A quick benchmark: $ python -m timeit -s ‘import operator; strings = [“a”]*10000’ ‘r = reduce(operator.add, strings)’ 100 loops, best of 3: 8.46 msec per loop $ python -m timeit -s ‘import … Read more
I’m assuming what you want to do (from your comment and linked post) is insert C code into a function. In that case, I would have thought you wouldn’t need to go so far as to write a compiler plugin. Have a look at Boost.Preprocessor, which can do very advanced manipulations of C code using … Read more
Testing strings with is only works when the strings are interned. Unless you really know what you’re doing and explicitly interned the strings you should never use is on strings. is tests for identity, not equality. That means Python simply compares the memory address a object resides in. is basically answers the question “Do I … Read more