mirror of
https://github.com/pocketpy/pocketpy
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60 lines
2.4 KiB
Markdown
60 lines
2.4 KiB
Markdown
---
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icon: dot
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label: 'Execute Python Code'
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order: 93
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---
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### Simple execution
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Once you have a `VM` instance, you can execute python code by calling `exec` method.
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#### `PyVar exec(Str source, Str filename, CompileMode mode, PyVar _module=nullptr)`
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+ `source`, the python source code to be executed
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+ `filename`, the filename of the source code. This is used for error reporting
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+ `mode`, the compile mode. See below for details
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+ `module`, the module where the code will be executed. If `nullptr`, the code will be executed in the `__main__` module
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`exec` handles possible exceptions and returns a `PyVar`.
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If the execution is not successful, e.g. a syntax error or a runtime exception,
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the return value will be `nullptr`.
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There are also overloaded versions of `exec` and `eval`, which is useful for simple execution:
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+ `PyVar exec(Str source)`
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+ `PyVar eval(Str source)`
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### Compile mode
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The `mode` parameter controls how the source code is compiled. There are 5 possible values:
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+ `EXEC_MODE`, this is the default mode. Just do normal execution.
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+ `EVAL_MODE`, this mode is used for evaluating a single expression. The `source` should be a single expression. It cannot contain any statements.
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+ `REPL_MODE`, this mode is used for REPL. It is similar to `EXEC_MODE`, but generates `PRINT_EXPR` opcode when necessary.
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+ `CELL_MODE`, this mode is designed for Jupyter like execution. It is similar to `EXEC_MODE`, but generates `PRINT_EXPR` opcode when necessary.
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+ `JSON_MODE`, this mode is used for JSON parsing. It is similar to `EVAL_MODE`, but uses a lexing rule designed for JSON.
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### Fine-grained execution
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In some cases, you may want to execute python code in a more fine-grained way.
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These two methods are provided for this purpose:
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+ `CodeObject_ compile(Str source, Str filename, CompileMode mode, bool unknown_global_scope)`
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+ `PyVar _exec(CodeObject_ co, PyVar _module)`
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1. `compile` compiles the source code into a `CodeObject_` instance. Leave `unknown_global_scope` to `false` if you don't know what it means.
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2. `_exec` executes the `CodeObject_` instance.
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!!!
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`_exec` does not handle exceptions, you need to use `try..catch` manually.
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!!!
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```cpp
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try{
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CodeObject_ code = vm->compile("a[0]", "main.py", EXEC_MODE, false);
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vm->_exec(code, vm->_main);
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}catch(TopLevelException e){
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// use e.summary() to get a summary of the exception
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std::cerr << e.summary() << std::endl;
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}
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```
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