.. _glossary: Glossary ======== .. if you add new entries, keep the alphabetical sorting and formatting! .. glossary:: annotator The component of the :term:`RPython toolchain` that performs a form of :term:`type inference` on the flow graph. See :ref:`annotator` in the documentation. backend Code generator that converts an :doc:`rpython` program to a :ref:`target language ` using the :term:`RPython toolchain`. compile-time In the context of the :term:`JIT`, compile time is when the JIT is generating machine code "just in time". external function Functions that we don't want to implement in Python for various reasons (e.g. they need to make calls into the OS) and whose implementation will be provided by the backend. garbage collection framework Code that makes it possible to write :doc:`RPython's garbage collectors ` in Python itself. guard a small test that checks if assumptions the JIT makes during tracing are still true JIT :doc:`just in time compiler `. llinterpreter Piece of code that is able to interpret flow graphs. This is very useful for testing purposes, especially if you work on the :term:`RPython` Typer. lltypesystem A :ref:`C-like type model ` that contains structs and pointers. A :term:`backend` that uses this type system is also called a low-level backend. The C backend uses this typesystem. low-level helper A function that the :term:`RTyper` can use a call to as part of implementing some operation in terms of the target :term:`type system`. ootypesystem An object oriented type model containing classes and instances. A :term:`backend` that uses this type system is also called a high-level backend. The JVM and CLI backends (now removed) used this typesystem. prebuilt constant In :term:`RPython` module globals are considered constants. Moreover, global (i.e. prebuilt) lists and dictionaries are supposed to be immutable ("prebuilt constant" is sometimes abbreviated to "pbc"). promotion :term:`JIT` terminology. *promotion* is a way of "using" a :term:`run-time` value at :term:`compile-time`, essentially by deferring compilation until the run-time value is known. See if :doc:`the jit docs ` help. RPython :doc:`rpython`, a limited subset of the Python_ language. The limitations make :term:`type inference` possible. It is also the language that the PyPy interpreter itself is written in. RPython toolchain :ref:`annotator`, :doc:`rtyper`, and various :term:`backend`\ s. rtyper Based on the type annotations, :doc:`rtyper` turns the flow graph into one that fits the model of the target platform/:term:`backend` using either the :term:`lltypesystem` or the :term:`ootypesystem`. run-time In the context of the :term:`JIT`, run time is when the code the JIT has generated is executing. specialization A way of controlling how a specific function is handled by the :term:`annotator`. One specialization is to treat calls to a function with different argument types as if they were calls to different functions with identical source. transformation Code that modifies flowgraphs to weave in translation aspects translation-time In the context of the :term:`JIT`, translation time is when the PyPy source is being analyzed and the JIT itself is being created. translator :ref:`Tool ` based on the PyPy interpreter which can translate sufficiently static Python programs into low-level code. type system The RTyper can target either the :term:`lltypesystem` or the :term:`ootypesystem`. type inference Deduces either partially or fully the type of expressions as described in this `type inference article on Wikipedia`_. The :term:`RPython toolchain`'s flavour of type inference is described in :ref:`annotator` section. .. _type inference article on Wikipedia: http://en.wikipedia.org/wiki/Type_inference .. _Python: http://www.python.org