Python 3.6.5 Documentation > "codeop" — Compile Python code
"codeop" — Compile Python code ******************************
**Source code:** Lib/codeop.py
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The "codeop" module provides utilities upon which the Python read- eval-print loop can be emulated, as is done in the "code" module. As a result, you probably don’t want to use the module directly; if you want to include such a loop in your program you probably want to use the "code" module instead.
There are two parts to this job:
1. Being able to tell if a line of input completes a Python statement: in short, telling whether to print ‘">>>"’ or ‘"..."’ next.
2. Remembering which future statements the user has entered, so subsequent input can be compiled with these in effect.
The "codeop" module provides a way of doing each of these things, and a way of doing them both.
To do just the former:
codeop.compile_command(source, filename="<input>", symbol="single")
Tries to compile *source*, which should be a string of Python code and return a code object if *source* is valid Python code. In that case, the filename attribute of the code object will be *filename*, which defaults to "'<input>'". Returns "None" if *source* is *not* valid Python code, but is a prefix of valid Python code.
If there is a problem with *source*, an exception will be raised. "SyntaxError" is raised if there is invalid Python syntax, and "OverflowError" or "ValueError" if there is an invalid literal.
The *symbol* argument determines whether *source* is compiled as a statement ("'single'", the default) or as an *expression* ("'eval'"). Any other value will cause "ValueError" to be raised.
Note: It is possible (but not likely) that the parser stops parsing with a successful outcome before reaching the end of the source; in this case, trailing symbols may be ignored instead of causing an error. For example, a backslash followed by two newlines may be followed by arbitrary garbage. This will be fixed once the API for the parser is better.
class codeop.Compile
Instances of this class have "__call__()" methods identical in signature to the built-in function "compile()", but with the difference that if the instance compiles program text containing a "__future__" statement, the instance ‘remembers’ and compiles all subsequent program texts with the statement in force.
class codeop.CommandCompiler
Instances of this class have "__call__()" methods identical in signature to "compile_command()"; the difference is that if the instance compiles program text containing a "__future__" statement, the instance ‘remembers’ and compiles all subsequent program texts with the statement in force.
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