Mailman 3 April 2015 - code-quality

assigning node type with function annotations?
by Jarrad Hope 07 May '15

07 May '15

Hello Been using astroid extensively this past week, really enjoying it! Great work! What's the best way I can deliberately set the type of an argument, based on the function annotations?

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Jedi 0.9.0 is now a static analysis library
by Dave Halter 04 May '15

04 May '15

Hi! This is an announcement to make you consider using Jedi as a static analysis library for your own stuff. If you want to build a refactoring or a linter library for Python you should just be using Jedi, it's doing all the work for you. I have recently released Jedi 0.9.0. This release marks a change in the way how Jedi is structured. In the past Jedi had one objective only: Autocompletion. Now Jedi is a general purpose, high quality static analysis engine. The static analysis capabilities are really good, but it's hard to describe what it does exactly. It's better than any other static analysis engine out there for sure. Jedi's parser is built on the lib2to3 and therefore is able to create a "round-trip" representation of source code. After parsing and modifications to the syntax tree, Jedi echos the exact same source tree with the changes included, which is neat for refactoring. The parser also has built-in error recovery as well as support for different Python versions (Python version is a param). Jedi has become quite powerful. If you're considering Jedi, I'm very happy to get you started. Let's talk! https://github.com/davidhalter/jedi/ ~ Dave

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Rebuilding AST with Astroid?
by Jarrad Hope 24 Apr '15

24 Apr '15

Hello I am currently using the Python ast package with ast.NodeVisitor to generate code for another VM. I found Astroid during my search for a type inference solution. The documentation is abit sparse for me, and I was hoping someone could help me with extending the AST with Astroid's. At first I tried AstroidManager().ast_from_file(f) but I got astroid.exceptions.AstroidBuildingException: Unable to load module tests/single_function.se (No module named tests/single_function.se) I then tried something like ast_se = ast.parse(code) module_se = TreeRebuilder(AstroidManager()).visit_module(ast_se, "blah", "blah", "blah") Which gets me a module, but I couldn't seem to pass it to MyNodeVisitor.visit(module_se) or ast.dump(module_se) (not surprising as it's not an AST) So my question is, how do I build an AST with Astroid from a stand-alone file, walk the ast in a fashion similar to NodeVisitor, and if possible query types from the extended AST nodes? Thanks, Jarrad

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Having trouble making pylint+astroid truly ignore context
by Daniel Balparda (梅巴達) 04 Apr '15

04 Apr '15

Hi, Inside Google we use pylint in many ways. In some we have plenty context for imports, etc. In others we have only on file in isolation and need to lint it the best we can without any context for imports, etc. To support that we have a pylint mode where it should ignore everything but the file given to it. This has been kind of working for a long time, but some bugs were filed where we noticed our pylint was in fact behaving differently for files with context available and those without. I eventually traced the issue to the fact that when astroid sees a star import (from foo import *) it will try to load symbols for the import. When the import makes sense (in one example, the file is in a directory where it may work) it succeeds in importing symbols; when the import makes no sense (in another example, the file is isolated somewhere python won't find any symbol to import) then it will not add the symbols. The specific place this happens is in astroid/builder.py: def add_from_names_to_locals(self, node): """store imported names to the locals; resort the locals if coming from a delayed node """ _key_func = lambda node: node.fromlineno def sort_locals(my_list): my_list.sort(key=_key_func) for (name, asname) in node.names: if name == '*': try: imported = node.do_import_module() except InferenceError: continue for name in imported.wildcard_import_names(): node.parent.set_local(name, node) sort_locals(node.parent.scope().locals[name]) else: node.parent.set_local(asname or name, node) sort_locals(node.parent.scope().locals[asname or name]) My questions is: Is there a (non-hacky) way of telling astroid/pylint that I really *really* don't want them to consider anything else from context and actually use only the file I provided? If not, is it reasonable to add an option for that? (I can do the coding, but not before discussing our options.) Thank you very much, Best regards, Daniel ι══ι══ι══ι══ι══ι══ι══ι══ι══ι══ι══ι══ι══ι══ι══ι══ι══ι══ι══ι *Daniel Balparda de Carvalho* 梅巴達 <balparda(a)google.com> Python Team, Google US-MTV-CL2 3K5B, +1-650-933-8587

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Possible spurious Flake8 warning F823
by Dan Wandschneider 03 Apr '15

03 Apr '15

All- It seems like when I have a function that does "del" on a global variable, flake complains that a local variable is referenced before assignment. As far as I know, the following is valid code: server = None def stopServer(): global server if server: del server server = None test.py:6:8: F823 local variable 'server' (defined in enclosing scope on line 1) referenced before assignment I'm using flake --version: 2.1.0 (pep8: 1.4.6, mccabe: 0.2.1, pyflakes: 0.7.3) I understand that the "del" statement is redundant, but I don't think that it is wrong, per se. Is this code actually incorrect? If not, is there a way to suppress this error message? I'm interested in figuring this out as part of an effort to convince a coworker to start using flake on his/her code. Thanks - Dan W.

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