astor – AST observe/rewrite¶
astor is designed to allow easy manipulation of Python source via the AST.
There are some other similar libraries, but astor focuses on the following areas:
- Round-trip back to Python via Armin Ronacher’s codegen.py module:
- Modified AST doesn’t need linenumbers, ctx, etc. or otherwise be directly compileable
- Easy to read generated code as, well, code
- Dump pretty-printing of AST
- Harder to read than round-tripped code, but more accurate to figure out what is going on.
- Easier to read than dump from built-in AST module
- Non-recursive treewalk
- Sometimes you want a recursive treewalk (and astor supports that, starting at any node on the tree), but sometimes you don’t need to do that. astor doesn’t require you to explicitly visit sub-nodes unless you want to:
- You can add code that executes before a node’s children are visited, and/or
- You can add code that executes after a node’s children are visited, and/or
- You can add code that executes and keeps the node’s children from being visited (and optionally visit them yourself via a recursive call)
- Write functions to access the tree based on object names and/or attribute names
- Enjoy easy access to parent node(s) for tree rewriting
This section is not done. Please look at the source code for all public members.
to_source(source, indent_with=' ' * 4, add_line_information=False)¶
Convert a node tree back into Python source code.
Each level of indentation is replaced with indent_with. Per default this parameter is equal to four spaces as suggested by PEP 8.
If add_line_information is set to
Truecomments for the line numbers of the nodes are added to the output. This can be used to spot wrong line number information of statement nodes.