Metadata-Version: 2.1
Name: flynt
Version: 0.47
Summary: CLI tool to convert a python project's %-formatted strings to f-strings.
Home-page: https://github.com/ikamensh/flynt
Author: Ilya Kamenshchikov
License: MIT
Description: # flynt - string formatting converter
        [![Build Status](https://dev.azure.com/ikamenshchikov/flynt/_apis/build/status/ikamensh.flynt?branchName=master)](https://dev.azure.com/ikamenshchikov/flynt/_build/latest?definitionId=1&branchName=master) ![Coverage](https://img.shields.io/azure-devops/coverage/ikamenshchikov/flynt/1) [![PyPI version](https://badge.fury.io/py/flynt.svg)](https://badge.fury.io/py/flynt)  [![Downloads](https://pepy.tech/badge/flynt)](https://pepy.tech/project/flynt)  [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
        
        
        `flynt` is a command line tool to automatically convert a project's Python code from old "%-formatted" and .format(...) strings into Python 3.6+'s "f-strings".
        
        F-Strings:
        
        > Not only are they more readable, more concise, and less prone to error than other ways of formatting, but they are also faster!
        
        ### Installation
        
        `pip install flynt`. It requires Python version 3.6+.  
         
        ### Usage
        
        *Flynt will modify the files it runs on. Add your project to version control system before using flynt.*
        
        To run: `flynt {source_file_or_directory}`
        
        * Given a single file, it will 'f-stringify' it: replace all applicable string formatting in this file (file will be modified).
        * Given a folder, it will search the folder recursively and f-stringify all the .py files it finds. It skips some hard-coded folder names: `blacklist = {'.tox', 'venv', 'site-packages', '.eggs'}`.
        
        It turns the code it runs on into Python 3.6+, since 3.6 is when "f-strings" were introduced.
        
        ### Command line options
        ```
        usage: flynt [-h] [--verbose | --quiet]
                     [--no-multiline | --line-length LINE_LENGTH]
                     [--transform-concats] [--fail-on-change]
                     src [src ...]
        
        positional arguments:
          src                   source file(s) or directory
        
        optional arguments:
          -h, --help            show this help message and exit
          --verbose             run with verbose output
          --quiet               run without output
          --no-multiline        convert only single line expressions
          --line-length LINE_LENGTH
                                for expressions spanning multiple lines, convert only
                                if the resulting single line will fit into the line
                                length limit. Default value is 88 characters.
          --transform-concats   Replace string concatenations (defined as + operations 
                                involving string literals) with f-strings. 
                                Available only if flynt is installed with
                                3.8+ interpreter.
          --fail-on-change      Fail when changing files (for linting purposes)
        ```
        
        ### Sample output of a successful run:
        ```
        38f9d3a65222:~ ikkamens$ git clone https://github.com/pallets/flask.git
        Cloning into 'flask'...
        ...
        Resolving deltas: 100% (12203/12203), done.
        
        38f9d3a65222:open_source ikkamens$ flynt flask
        Running flynt v.0.40
        
        Flynt run has finished. Stats:
        
        Execution time:                            0.789s
        Files modified:                            21
        Character count reduction:                 299 (0.06%)
        
        Per expression type:
        Old style (`%`) expressions attempted:     40/42 (95.2%)
        `.format(...)` calls attempted:            26/33 (78.8%)
        F-string expressions created:              48
        Out of all attempted transforms, 7 resulted in errors.
        To find out specific error messages, use --verbose flag.
        
        _-_._-_._-_._-_._-_._-_._-_._-_._-_._-_._-_._-_._-_._-_._-_._-_._-_._-_._-_._-_._-_._-_._-_._-_._-_.
        Please run your tests before commiting. Did flynt get a perfect conversion? give it a star at:
        ~ https://github.com/ikamensh/flynt ~
        Thank you for using flynt. Upgrade more projects and recommend it to your colleagues!
        
        38f9d3a65222:~ ikkamens$
        ```
        
        ### Pre-commit hook
        
        To make sure all formatted strings are always converted to f-strings, you can
        add flynt to your [pre-commit](https://www.pre-commit.com) hooks.
        
        Add a new section to `.pre-commit-config.yaml`:
        ```
           - repo: local
             hooks:
                 - id: flynt
                   name: flynt
                   entry: flynt
                   args: [--fail-on-change]
                   types: [python]
                   language: python
                   additional_dependencies:
                       - flynt
        ```
        
        This will run flynt on all modified files before commiting.
        
        You can skip conversion of certain lines by adding `# noqa [: anything else] flynt [anything else]`
        
        
        ### About
        
        Read up on f-strings here: 
        - https://realpython.com/python-f-strings/
        - https://www.python.org/dev/peps/pep-0498/
        
        After obsessively refactoring a project at work, and not even covering 50% of f-string candidates, I realized there was some place for automation. Also it was very interesting to work with ast module. 
        
        ### Dangers of conversion
        It is not guaranteed that formatted strings will be exactly the same as before conversion.
        
        `'%s' % var` is converted to `f'{var}'`. There is a case when this will behave different from the original -  if var is a tuple of one element. In this case, %s displays the element, and f-string displays the tuple. Example:
        
        ```
        foo = (1,)
        print('%s' % foo) # prints '1'
        print(f'{foo}')   # prints '(1,)'
        ```
        
        Furthermore, some arguments cause formatting of strings to throw exceptions. One example where f-strings are inconsistent with previous formatting is %d vs {:d} - new format no longer accepts floats. While most cases are covered by taking the formatting specifiers to the f-strings format, the precise exception behaviour might differ as well. Make sure you have sufficient test coverage.
        
        ### Other Credits / Dependencies / Links
        
        - [astor](https://github.com/berkerpeksag/astor) is used to turn the transformed AST back into code.
        - Thanks to folks from [pyddf](https://www.pyddf.de/) for their support, advice and participation during spring hackathon 2019, in particular Holger Hass, Farid Muradov, Charlie Clark.
Keywords: utility,strings
Platform: UNKNOWN
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.6
Classifier: Programming Language :: Python :: 3.7
Classifier: Programming Language :: Python :: 3.8
Classifier: Topic :: Software Development :: Libraries :: Python Modules
Classifier: Topic :: Utilities
Requires-Python: >=3.6
Description-Content-Type: text/markdown
