pocketpy/docs/quick-start/exec.md

icon	label	order
dot	Execute Python code	93

Once you have a VM instance, you can execute python code by calling exec method.

PyObject* exec(Str source, Str filename, CompileMode mode, PyObject* _module=nullptr)

• source, the python source code to be executed
• filename, the filename of the source code. This is used for error reporting
• mode, the compile mode. See below for details
• module, the module to be executed. If nullptr, the code will be executed in the __main__ module

exec handles possible exceptions and returns a PyObject*. If the execution is not successful, e.g. a syntax error or a runtime exception, the return value will be nullptr.

Compile mode

The mode parameter controls how the source code is compiled. There are 4 possible values:

• EXEC_MODE, this is the default mode. Just do normal execution.
• EVAL_MODE, this mode is used for evaluating a single expression. The source should be a single expression. It cannot contain any statements.
• REPL_MODE, this mode is used for REPL. It is similar to EXEC_MODE, but generates PRINT_EXPR bytecode for global expressions.
• JSON_MODE, this mode is used for JSON parsing. It is similar to EVAL_MODE, but uses a lexing rule designed for JSON. For example, true will be parsed as True.

Fine-grained execution

In some cases, you may want to execute python code in a more fine-grained way. These two methods are provided for this purpose:

• CodeObject_ compile(Str source, Str filename, CompileMode mode, bool unknown_global_scope)
• PyObject* _exec(CodeObject_ co, PyObject* _module)

compile compiles the source code into a CodeObject_ instance. _exec executes the CodeObject_ instance. It does not handle exceptions, so you may need to use try..catch manually.