mirror of
https://github.com/pocketpy/pocketpy
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79 lines
1.8 KiB
Markdown
79 lines
1.8 KiB
Markdown
---
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icon: dot
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label: 'Create modules'
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order: 50
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---
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Modules are stored in `vm->_modules` and `vm->_lazy_modules`.
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They are both dict-like objects.
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### Lazy modules
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A lazy module is a python source file.
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It is compiled and executed when it is imported.
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Use `[]` operator to add a lazy module.
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```cpp
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vm->_lazy_modules["test"] = "pi = 3.14";
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```
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```python
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import test
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print(test.pi) # 3.14
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```
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### Native modules
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A native module is a module written in c++ or mixed c++/python.
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Native modules are always compiled and executed when the VM is created.
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To creata a native module,
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use `vm->new_module(...)`.
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```cpp
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PyObject* mod = vm->new_module("test");
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mod->attr().set("pi", VAR(3.14));
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vm->bind_func<2>(mod, "add", [](VM* vm, ArgsView args){
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i64 a = CAST(i64, args[0]);
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i64 b = CAST(i64, args[1]);
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return VAR(a + b);
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});
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```
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```python
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import test
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print(test.pi) # 3.14
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print(test.add(1, 2)) # 3
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```
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### Module resolution order
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When you do `import` a module, the VM will try to find it in the following order:
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1. Search `vm->_modules`, if found, return it.
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2. Search `vm->_lazy_modules`, if found, compile and execute it, then return it.
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3. Search `vm->_path` and try to load it from file system.
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### Filesystem hook
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You can use `set_read_file_cwd` to provide a custom filesystem hook, which is used for `import` (3rd step).
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The default implementation is:
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```cpp
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set_read_file_cwd([](const Str& name){
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std::filesystem::path path(name.sv());
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bool exists = std::filesystem::exists(path);
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if(!exists) return Bytes();
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std::string cname = name.str();
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FILE* fp = fopen(cname.c_str(), "rb");
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if(!fp) return Bytes();
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fseek(fp, 0, SEEK_END);
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std::vector<char> buffer(ftell(fp));
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fseek(fp, 0, SEEK_SET);
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fread(buffer.data(), 1, buffer.size(), fp);
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fclose(fp);
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return Bytes(std::move(buffer));
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});
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``` |